THE NATIONAL SHIPBUILDING RESEARCH PROGRAMDallas TX 75243 Phone 214-272-3003 ACKNOWLEDGMENTS (Continued) AAIR Purification Systems Jeff Storey 1250 Pierre Way El Cajon, CA 92021 (619)

SHIP PRODUCTION COMMITTEEFACILITIES AND ENVIRONMENTAL EFFECTSSURFACE PREPARATION AND COATINGSDESIGN/PRODUCTION INTEGRATIONHUMAN RESOURCE INNOVATIONMARINE INDUSTRY STANDARDSWELDINGINDUSTRIAL ENGINEERINGEDUCATION AND TRAINING

THE NATIONALSHIPBUILDINGRESEARCHPROGRAM

August 1995NSRP 0457

Characterizing Shipyard WeldingEmissions and Associated ControlOptions

U.S. DEPARTMENT OF THE NAVYCARDEROCK DIVISION,NAVAL SURFACE WARFARE CENTER

in cooperation with

National Steel and Shipbuilding CompanySan Diego, California

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4. TITLE AND SUBTITLE The National Shipbuilding Research Program, Characterizing ShipyardWelding Emissions and Associated Control Options

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These reports were prepared as an account of government-sponsored work. Neither theUnited States, nor the United States Navy, nor any person acting on behalf of the UnitedStates Navy (A) makes any warranty or representation, expressed or implied, with respectto the accuracy, completeness or usefulness of the information contained in this report/manual, or that the use of any information, apparatus, method, or process disclosed in thisreport may not infringe privately owned rights; or (B) assumes any liabilities with respect tothe use of or for damages resulting from the use of any information, apparatus, method, orprocess disclosed in the report. As used in the above, “Persons acting on behalf of theUnited States Navy” includes any employee, contractor, or subcontractor to the contractorof the United States Navy to the extent that such employee, contractor, or subcontractor tothe contractor prepares, handles, or distributes, or provides access to any informationpursuant to his employment or contract or subcontract to the contractor with the UnitedStates Navy. ANY POSSIBLE IMPLIED WARRANTIES OF MERCHANTABILITY AND/ORFITNESS FOR PURPOSE ARE SPECIFICALLY DISCLAIMED.

U.S. DEPARTMENT OF THE NAVYCARDEROCK DIVISION,NAVAL SURFACE WARFARE CENTER

in cooperation with

National Steel and Shipbuilding CompanySan Diego, California

FINAL REPORT

CHARACTERIZING SHIPYARD WELDING EMISSIONSAND ASSOCIATED CONTROL OPTIONS

Prepared By:Zachary F. Jacobs, P.E.

Jacobs Environmental Engineering Services5006 Mission Boulevard

San Diego, California 92109

forNATIONAL STEEL AND SHIPBUILDING COMPANY

Harbor Drive and 28th StreetPost Office Box 85278

San Diego, CA 92186-5278

In Behalf OfSNAME SPC PANEL SP-1

FACILITIES AND ENVIRONMENTAL EFFECTS

Under theNATIONAL SHIPBUILDING RESEARCH PROGRAM

August 1995Task N1-92-1, Subtask 1

This report was funded as an addendumsub-project under the NSRP Project entitledAir Toxics Emissions Evaluations (N-3-93).The Air Toxics Emissions Project had twoprimary objectives (I) identify and quantifyregulated toxic air pollutants emitted fromshipyard operations and (II) develop adatabase and analyze cost effective air toxiccontrol strategies. This sub-project focuseson collection, filtration, and emission factorsfor potentially toxic welding emission.

Potentially toxic welding emissions havecome under recent scrutiny with EPAregulations and regulatory agencies. Withthe signing of the Clean Air Act Amendments(CAAA) of 1990, shipyards face some of themost significant regulatory legislation everenacted. Title Ill regulates hazardous airpollutants (HAPs) and poses the greatestcost and technical challenge for compliance.Title Ill requirements will be imposed equallyon each air quality area. Under Title V, mostshipyards will be required to obtain federallyenforceable operating permits that could limitshipyard operations and increasinglyregulate emissions. Therefore, it is extremelyimportant that shipyards understand theconstraints and opportunities available forwelding emission reductions, collection, andfiltration when addressing the CAAA of 1990.

A comprehensive analysis was performed todetermine when, where, and why weldingoccurs in the shipyard. Then, investigationswere directed at vendors and manufacturersof weld fume extraction and filtrationequipment.

Determining collection equipmentconfigurations for the shipbuilding environmentis a very diffcult task because shipyards havean extremely diverse set of facilities. Eachfacilities and/or production area must beanalyzed on a case by case basis. informationpresented in this report should helpshipyards analyze their opportunities.

At present there is limited data available fordeveloping standard or specific weldingemission factors. Current technical reports andliterature contain emission data for selectedrods, electrodes and wires, under limitedvariations, in operating conditions. Even withlimited data, emission factors have beendeveloped for electric arc welding operations.Chapter 4 presents an introduction to currentemission factors and their derivation. Researchwas performed and four of the most currantsources of emission factors are presented.

Environmental and occupational health andsafety regulations regading welding emissionsare fast becoming a concern for shipyads andtheir management throughout the nation. Thisdocument should serve as a source ofinformation that presents an introduction toshipyard welding processes, availableinformation concerning current emissionfactors, and options for collection and filtrationof welding fumes in the shipyard productionenvironment

DOCUMENT OVERVIEW

Chapter 1) Legislative BackgroundThis chapter is a summary of major federal andstate environmental and employee safetyregulations surrounding potentially toxicwelding emissions. Federal legislation involvesthe Clean Air Act Amendments (CAM) of1990, and the Occupational Health and SafetyAct (OSHA) indoor air quality regulations andemployee toxic exposure limitations. Allshipyards are governed by federal laws andregulations, which are continually increasing inrigidity with respect to exposure of employeesand the general public to toxic emissions.California has some unique regulations thatextend beyond federal requirements, whichimpose increased requirements on Californiashipyards for air toxics reporting, accountability,and local health risk assessments. Californiaregulations are described briefly to provideaddtional information and insight on thesubject matter and illustrate possible federaltrends. Many other states also have unique airquality regulations and requirements.Shipyards should consult their respective localand state regulations for specific information.

Chapter 2) Shipyard Welding OperationsShipyard welding processes, or morespecifically fusion arc welding, is performedat nearly every location in the shipyard. Theprocess involves joining metals by bringingadjoining surfaces to extreme temperaturesand fused together with a molten fillermaterial. The types of arc welding processesused by shipyards are presented asbackground for greater processunderstanding.

Chapter 3) Fume Collection and FiltrationTechnologiesThis chapter provides an introduction to avariety of weld fume collection and filtrationtechnologies and equipment. The advantagesand disadvantages of filtration technologies areinvestigated and analyzed with respect tomaintenance, durability, and filtration efficiency.Weld fume colletion equipment confiturationsare analyzed with respect to their applicabilityto the shipyard operational environment andproduction process areas.

Chapter 4) Current Arc Welding EmissionFactor InformationChapter 4 is presented to provide the mostcurrent information available about emissionfactor development and derivations. Fourmain sources of information are presented,which include: 1) Federal AP-42 EmissionFactors, 2) SARA Guidance on welding fume emissions, 3) California Air Resources BoardPosition, and 4) National Steel andShipbuilding Company (NASSCO) derivedemission factors. A summary of all emissionfactors is provided to help explain thecomplexities and possible inaccuraciesassociated with estimating welding emissionsusing available emission factors.

ii

The National Shipbuilding ResearchProgram (NSRP), Zachary F. Jacobs P. E.,Engineering Contractor, and Dan Buell,NASSCO, would like to acknowledge themany people who gave their support andassistance throughout this project. Severalindividuals participated in written surveys andphone interviews, which provided much ofthe needed data for this study. Vendors andmanufacturers of weld fume collection andfiltration equipment provided informationabout their products and specific applicationsthey experienced. The shipbuilding andrepair industry offered information about theirrespective operations, facilities and stateregulations concerning welding emissions. Acopy of the surveys sent to the NSRPmembers and equipment manufacturers aresupplied in Appendix 2 and 3 respectively.

NSRP Shipyard SP-1 Panel Members

Steve Lacoste, Mike Simpson, & MalcolmAndry Avondale Industries, Inc.

Richad Propsom & John MeachumPeterson Builders, Inc.

Jim CorcoranBethlehem Steel,BethShip Sabine Yard

Mike Chee, Mike Sulivan, & Dan BuellNational Steel & Shipbuilding Company(NASSCO)

Dana M. AustinSouthwest Marine

Ken CongletonNewport News Shipbuilding

Robert Benze & Clark PitchfordPuget Sound Shipyard

Doug FordNORSHIPCO

Flectcher HuntPort of Portland

David DonaldsonCascade General

Manufactures and Vendors of WeldFume Collection and FiltrationEquipment

AircologyTom VolzCustom ParkOld Saybrook, CT 064751-800-828-6123

Air Quality EngineeringMark S. Molzen3340 Winpark Dr.Minneapolis, MN(800) 328-0787

Airflow Systems, Inc.Tony Bodmer11370 Pagemille RoadDallas TX 75243Phone 214-272-3003

ACKNOWLEDGMENTS (Continued)

AAIR Purification SystemsJeff Storey1250 Pierre WayEl Cajon, CA 92021(619) 588-2825AaircareTom Mazzocco7007 Nutmeg WayP.O. Box 4487Carisbad, Ca 92018(619) 438-4774

United Air Specialists, Inc.DMARK Corporation Chris Kane & JayDavis 218 Atlantic AvenueLong Beach, CA 90802(310) 795-0611

FARR Sales and ServiceTony Vidmar2201 Park PlaceEl Segundo, CA 90246(310) 536-6780 (300) 300-3277

Micro Air, Air CleanersJim KantanaPO BOX 1138Wichita, KS 67201(316) 943-2351

Universal Air PrecipitatorKurt Kondas1500 McCully RoadMonroeville PA 15146(412) 372-0706

NIKRO Industries Inc638 N. Iowa,Villa Park, IL 60181(708) 530-0558

Dust Control Env. Systems6145 Deifield Indl. Drive, Dept. 2WaterFord, Ml 48329(800) 728-3841

Gardner AireRonnie Dukes, 1201 W. Lake St.Horicon, Wl 53032(800) 558-8890Engwald CorporationKen Eble, 125 Sheridan BlvdInwood, L.I. N.Y.(516) 371-2222

Air Cleaning Specialist, Inc.J.C. Jordan, 183 El Camino RealMilibrae CA 94030(800) 633-4007

Air Cleaning Equipment Co.P.O. BOX 1399,Wyane, New Jersey 07474-1399(800)221-5318

CAR-MON Products Inc.Fred Imming 1225-T Davis RoadElgin, IL 60123(708) 695-9000

SOURCES OF INFORMARTION

Chapter 1:US EPA, Office of Air and Radiation,Implementation Stfategy for the Clean Air ActAmendments of 1990, January 1990

Latham and Watkins, The Clean Air ActAmendments of 1990, A Summary of KeyPrevisions, July 1990

Clean Air Permits, Managers Guide to The1990 Clean Air Act Amendments of 1990,Thompson Publishing Group, Jan 1995

US EPA, Office of Research andDevelopment Facility Pollution PreventionGuide, May 1992

EPA, SARA 313, Community Right to Know,October 1990

Virginia L. Moris, Arthor D. Little Inc. TheAerospace Industry: An Impact Assessment ofthe 1990 CAAA, Metal Finishing, April 1995

Chapter 2:American Welding Society (AWS) WeldingHand Book ,Welding Processes, And, Metelsand Their Weldability, 1991 / 1983

Roy Lindbergh, Processes and Materials ofManufacture, Fourth Edition, 1990

Cary, Howard, B. Modern WeldingTechnology, Prentice-Hall Inc., 1985

Okayama, Y. & Chirillo, L.D., Product WorkBreakdown Structure, NSRP 1982

Richard Lee Storch, Colin P. Hammon &Howard M. Bunch, Ship Production, CornellMaritime Press lnc.,1988

D'Arcangelo, E., Ship Design andConstruction, society of Naval Architects andMarine Engineers 1989

Chapter 3:L. Bauer, How to elect Exhaust Equipment,Welding Desian and Fabrication, 847,27-31,July 1991

G.C. Barns, Control of Fumes in the WeldingEnvironment, Svetsaren, 1:16-18, 1990

C.N. Gray & P.J. Hewitt, Control of ParticulateEmission from Electric Arc, 1981

Welding by Process Modification,Occupational Hvgiene, 1982

I.W. Head and S.J. Silk, Integral FumeExtraction in MIG Gun Welding, MetalConstruction, December 1979

L. Baver, How to Select Exhaust Equipment,Welding Design and Fabrication, July 1991

Chapter 4:US EPA, Office of Air QuaIity Planing andStandards Emissions Inventory Branch,Development of Particulate and HazardousEmission Factors for Electric Arc Welding (AP-42, Section 12.19)

R.M. Evans et al., Fumes and Gasses in theWelding Environment, American Weld Society(AWS)

Corespondance Memo from Richard Bode,(CARB) Manager of Special Pollutants toCraig Anderson, SDAPCD, August 27,1993

EPA 580/4.90.0.2, Toxic Chemical Releaselnventory Claticetion and Guidance for theMetal Fabrication industry, January 1990

Air & Waste Management Association(AWMA), Emission Factors for Arc Welding,Gerstle, R.W. et al. 86th Annual Meeting,Denver, Co., 1993

i v

Executive SummaryDocument OverviewAcknowledgmentsSources of Information

Chapter 1. Legislative Background1.11.21 .3

1.41.51.61.7

IntroductionClean Air Act Amendments of 1990California Toxic Regulations

1.3.1 Proposition 65 “Right to Know”1.3.2 AB 2588 Toxic Hot Spots Act of 1987

SARA Title Ill, Section 313, Toxic Release Inventory (TRl)Occupational Health and Safety Administration (OSHA) Air Quality LegislationHexavalent Chromium and the LegislationList-of-list Chemicals and Summary

Chapter 2. Shipyard Welding Operations2.1 Shipbuilding Materials2.2 Common Shipyard Welding Processes

2.2.12.2.22.2.32.2.42.2.52.2.62.2.72.2.8

Shielded Metal Arc Welding (SMAW)Submerged Arc Welding (SAW)Gas Metal Arc Welding (GMAW)Gas Tungsten Arc Welding (GTAW)Flux Core Arc Welding (FCAW)Plasma-Arc Welding (PAW)Gas Welding, Brazing and SolderingOther Welding Processes

Chanter 3. Welding Fume Collection and Filtration Technologies3.1 Introduction3.2 Filtration Technology and Emissions, Collection Equipment

3.2.1 Efficiency Rating Systems3.2.2 Electrostatic Precipitators (ESP)3.2.3 Mechanical Filtration Devices

3.2.3.1 Media Bag Filters3.2.3.2 Cartridge Filter3.2.3.3 High Efficiency V-Bank Filters Media Filters3.2.3.4 HEPA filters 99.97% efficient

3.2.4 Filtration Selection (Mechanical vs. ESP)3.3. Collection Equipment and Configuration Alternatives

3.3.1 Source Capture Systems3.3.2 Canopy Capture Systems3.3.3 Non-Source and Unducted Capture Systems

Page #

ii i. . .iiiiv

1-11-11-21-21-31-31-41-51-6

2-12-12-32-32-42-52-52-62-72-7

3-13-13-13-23-33-43-43-53-53-63-73-73-83-9

3.3.4 Standardized Equipment Configurations Available3.3.4.1 Self-Contained Fan/Filter Units3.3.4.2 Module Configurations

3.4 Applicability of Equipment to Shipbuilding and Repair Processes and Facilities3.4.1 End of the Line Filtration

3.4.1.1 Operational Pros3.4.1.2 Operational Cons

3.4.2 Self Contained Roll-Around Units with 6 to 14 ft. of Arm Reach3.4.2.1 Operational Pros3.4.2.2 Operational Cons

3.4.3 Vacuum Units Connected to Weld Guns3.4.3.1 Operational Pros3.4.3.2 Operational Cons

3.4.4 Light Weight Portable Vacuum/Filtration Units3.4.4.1 Operational Pros3.4.4.2 Operational Cons

3.4.5 Canopy Hood Collection With or Without Curtains (Area Capture)3.4.5.1 Operational Pros3.4.5.2 Operational Cons

3.4.6 Non-Source Capture Modules3.4.6.1 Operational Pros3.4.6.2 Operational Cons

Chapter 4. Current Arc Welding Emission Factor Information4.1 Introduction4.2 Background4.3 Available Information on Arc Welding Emission Factors

4.3.1 NASSCO Developed Emission Factors4.3.1.1 Emission Factor Development4.3.1.2 Summary of NASSCO Developed Emission Factors

4.3.2 California Air Resources Board (CARB) Emission Factor Evaluation4.3.2.1 Emission Factor Development4.3.2.2 Summary of CARB Emission Factors

4.3.3 1990 SARA Section 313 Reporting issue Paper4.3.3.1 Emission Factor Development4.3.3.2 Summary of SARA 313 Emission Factors

4.3.41994 MRI AP-42 Emission Factors for Electronic Arc Welding4.3.4.1 Emission Factor Development4.3.4.2 Summary of SARA 313 Emission Factors

Appendix 1. Shipyard SurveyFromAppendix 2. Manufacturer Survey FromAppendix 3. Shipbuilding Processes, Practices, and Operations

3-103-113-123-133-143-143-153-153-163-163-173-173-173-173-183-18

3-183-193-193-193-193-19

4-14-14-24-24-34-74-84-104-104-114-114-134-144-154-19

LIST OF TABLES & FIGURES

Chapter 1Table 1-1Table 1-2Chapter 2Table 2-1Table 2-2Table 2.3Table 2.4Table 2.5Table 2.6Table 2.7Table 2-8Figure 2-1Figure 2-2Figure 2-3Figure 2-4Figure 2-5Figure 2-6Figure 2-7Chapter 3Table 3-1Table 3-2Table 3-3Figure 3-1Figure 3-2Figure 3-3Figure 3-4Figure 3-5Figure 3-6Figure 3-7Figure 3-8Figure 3-9Figure 3-10Figure 3-11Figure 3-12Figure 3-13Chapter 4Table 4-1Table 4-2Table 4-3Table 4-4Table 4-5Table 4-6Table 4-7Table 4-8Table 4-9Table 4-10

Reportable/Regulated Components of Electrodes, Rods, & WireList of List Reference for Weld Rod Constituents

Welding lndustry Purchase Breakdown in 1991National Steel and Shipbuilding 1991 BreakdownAdvantages and Disadvantages of SMAW Welding ProcessesAdvantages and Disadvantages of SAW Welding ProcessesAdvantages and Disadvantages of GMAW Welding ProcessesAdvantages and Disadvantages of GTAW Welding ProcessesAdvantages and Disadvantages of FCAW Welding ProcessesWelding Process Comparison MatrixDiagram of SMAW Welding ProcessDiagram of SAW Welding ProcessDiagram of GMAW Welding ProcessDiagram of GTAW Welding ProcessDiagram of Flux Core WireDiagram of FCAW Welding ProcessDiagram of Plasma Arc Welding Process

Source Capture Variables Recommended by OSHAPotential Reasons for Non-Source CapturePotential Alternatives to Shipyard Weld Fume CollectionElectronic Precipitator Flow DiagramMechanical Filtration SystemsMedia Bag Filter, Cube Filter and PrefilterCartridge Filters and Reverse Pulse CleaningHEPA FiltersTypical Source Capture ArrangementTypical Canopy Hood ArrangementTypical Non-Source Capture ArrangementTypical Modular System ConfigurationMultiple Station Collection Station with Filtration UnitSelf Contained Roll-Around UnitsWeld Gun UnitsLight Weight Portable

Raw Data Used For Estimating Parameters in Emissions CalculationsHexavalent Chromium Emission Parameters for SMAW OperationsHexavalent Chromium Emission Parameters for GMAW OperationsDerived Hexavalent Chromium Emission FactorsDerived Nickel Emission FactorsSummary of CARB Chromium Emission FactorsSummary of CARB - Other Metals- Emission FactorsReference Documents Used for AP42 Emissions Factor DeterminationPM-10 Emission Factors For Welding OperationsHazardous Air Pollutant (HAP) Emission Factors for Arc Welding

Page #

1-81-9

2-32-32-42-52-62-62-72-82-32 42-52-52-62-62-7

3-133-153-223-43-63-73-83-93-133-143-163-193-233-253-273-29

4-44-64-64-84-94-104-114-174-194-20

Chapter 1. Legislative Background

1.1 IntroductionThis chapter provides a summary of majorfederal environmental and employee safetyregulations surrounding emissions ofpotentially toxic welding emissions. Federallegislation that potentially affect weldingemissions include the Clean Air ActAmendments (CAAA) of 1990, SARA Title III,and the Occupational Health and Safety Act(OSHA) indoor air quality regulations andemployee toxic exposure limitations. Allshipyards are governed by federalenvironmental and occupation health andsafety laws and regulations, which arecontinually increasing in rigidity with respect toexposure of employees and public to toxicemissions. California has a some uniqueregulations that extend beyond federalrequirements that put increased requirementson California shipyards air toxic reporting,accountability and local health riskassessments. Two regulations unique toCalifornia are described briefly to provideaddtional information and insight on thesubject matter and illustrate possible federaltrends. Many other states also have unique airquality regulations and requirements.Shipyards should consult their respective localand state regulations and regulatory agenciesfor specific information. With increasingenvironmental and health and safetyregulations concerning potentially toxic weldingtimes and particulates, controlling emissions isfast becoming a concern for shipyards andtheir management throughout the nation.

1.2 Clean Air Act Amendments (CAAA) of1990With the signing of the Clean Air ActAmendments (CAAA) of 1990, industry(shipyards in particular), now face some of themost significant regulatory legislation everenacted. The CAAA Amendments of 1990contain 11 new and amended titles, including

enhanced non-attainment area provisions,addtional condtions for controlling hazardousair pollutants (HAPs), expanded emissionsmonitoring, record keeping, and increasedenforcement authority. Title I, III and V arebriefly discussed to provide some background.

Title I of the CAAA focuses on achievingnational ambient air goals and provides for anambitious program to reduce atmosphericozone through a combination of measures,including substantial reductions in volatileorganic compound’s (VOC’s). The majority ofVOC’s are emitted from shipyard matingprocesses and other surface preparation andsolvent cleaning operations. Title I provisionsrequire the development of ControlTechnologies Guidelines (CTG’s) that industrymust follow to reduce Iocalized ozoneproblems. All control technologies must meetwith specfic operating guidelines identified byregulatory agencies and industry. lndustry willbe required to use reasonably available controltechnology (RACT) to achieve reductions setforth in the legislation. Title 1 does have anaffect on shipyard welding operations, althoughit displays the potential extremes that may berequired to reduce or eliminate emissions.

Title Ill addresses toxic air emissions orHazardous Air Pollutants (HAPs). The CAAAspecifically directs the reduction of 189 of themost hazardous and pervasive air toxicsthrough the issuance of maximum availablecontrol technology (MACT) standards for allmajor sources of these air toxics within 10years. The maximum degree of reduction inemissions can be achieved through a variety of.measures, processes, methods, systems, ortechniques, including design and operationalchanges. Table 1, presented at the end of thissection, displays substances that can bepresent in welding electrodes and filler metals.Potential HAP emissions listed in Title Ill are

Characterizing Shipyard Welding Emissions and Associated Control OptionsPage 1-1


presented as item O in the reportable listcolumn of Table 1. Title Ill depicts that control ofHAP emissions should to be phased in overthe next ten years. Specific control of HAPpollutants will be a function of the amount ofpollutant a facility emits on a routine basis andthe control options available.

The cornerstone of the CAAA is the Title Voperating permits program. The purpose of theprogram is to establish a central point fortracking all applicable air quality requirementsand emissions for every source required toobtain an operating permit. Under Title V, all“major” sources of air pollution Will needpermits to operate and a majority of shipyardswill lit into this category. Although many stateshave previously adopted regulations tequiringa form of operating permit this is the first timethat a uniform approach has been adoptedthroughout the nation. Now, all aspects of theCAAA will be established through one federalmechanism implemented be states. in manycases, welding processes must be addresseson the Title V permit, which could potentiallyimpose process changes and restrictions.

1.3 California Air Toxic Issues:1.3.1 Proposition 65 “Right to Know”The Safe Drinking Water and ToxicsEnforcement Act of 1986 (Prop. 65) wasenacted by California voters, through the statesvoter initiative process and has three separateobjectives: (1) it requires the development of aIii of chemicals that are consideredcarcinogenic and/or a reproductive toxin (2)that then? be a dear and reasonable warning toexposed individuals before a businessknowingly and intentionally exposes individualsto a listed chemical; and, (3) it prohibits abusiness from knowingly discharging orreleasing a listed chemical into a source ofdrinking water. The previsions regardingdischarges and warnings apply only to Prop. 65

“listed" chemicals and to business activitiesreferred to as actions of “persons in the courseof doing business.” Preposition 65 is “right toknow’ legislation requiring California industry tonotify and warn the public of exposure tocarcinogens and teratogens. Shipyardspotentially emit both carcinogens (hexavalentchromium, cadmium, and nickel) and ateratogen (lead).

1.3.2 AB 2588 Air Toxic Hot Spots Act of1987The Air Toxics Hot Spots Information andAssessment Act Assembly Bill 2588 (AB-2588) was enacted in 1987. AB-2588 wasenacted in response to public concerns aboutthe release of toxic air contaminants to theatmosphere and residential aneas nearindustry. Under the Act stationary sources arerequired to report the types and quantity ofcertain substances their facility routinelyreleases into the air. The goals of the Air ToxicsHot Spots Act are to collect emission data,identify facilities that have potential localizedhealth and environmental impacts, ascertainthe associated risks, and to notify all nearbyresidents of “significant” health risks. The billhas been amended to include the continuousreduction of emissions and associatedsignificant health risks by identified facilities.

The process established by the Act requiresowners and operators of facilities to prapareand submit an air toxics inventory plan,subsequent emissions inventory, and for highpriority facilities, a health risk assessmentcstudy. The health risk assessments arereviewed and approved by the local AirPollution Control Districts (District), the State AirResources Board, and the Office ofEnvironmental Health Hazard Assessment(OEHHA). Facilities that present a potentiallysignificant health risk must notify exposedindividuals and implement a plan to reduce



risks below the significant level. The AirResources Board (ARB) and the District arerequired to develop a program to make theemission data available to the public. Districtsalso publish annual reports that summarize thehealth risk assessment program, rank facilitiesaccording to the cancer risk posed, identify thefacilities posing non-cancer health risks, anddescribe status on the development of controlmeasures.

1.4 SARA Title Ill, Section313, Toxic Release Inventory(TRI) Reporting:In the fall of 1986, Congresspassed the EmergencyPlanning and Community Right-to-Know Act This law, Title Ill ofthe Superfund Amendmentsand Reauthorization Act(SARA). directs states,communities and industry towork together to plan forchemical accidents, developinventories of hazardoussubstances, track toxic chemicalreleases and provide theinformation to the public. SARATitle Ill is the beginning of whatmany consider to be “regulationby information”. For the first

SARASection301-303

304

311

312

313

time, the public has access to informationabout industrial facilities, chemical produdionand processes, including quantities. The publicis also made aware of emissions and releasesof chemicals to the air and water fromproduction operations, and to the land in thefrom of spills.

SARA Title Ill consist of several sections thatrequire industry to report facility specificchemical information. The sections andassociated requirements and relevant chemicallist are presented in the SARA table.

Some of the metals present in weldingelectrodes and wire filler are reportable underSARA Section 313. For example, Aluminum,Copper, Chromium, and Nickel must beidentified on a Form R, if they meet thethreshold quantities required under Section313 (TRI). Release estimates for these metalsis briefly discussed in Chapter4.

Topic

EmergencyPlanning

EmegencyNotification

CommunityRight-to-

KnowCommunnity

Right-to-KnowToxic

ReleaseReporting

Requirement Chemical List

LEPC ExtremelyEmergency Plan Hazardous

SubstancesAccidental EHSs andRelease CERCLA (102a)

Reporting Substances MSDSs or List of OSHA

Chemicals HazardousChemicals

Inventories and OSHALocations Hazardous

ChemicalsForm R, Total TRl Chemicals

Annual Releases and Categories

Federal and state regulations affectinghazardous materials/wastes and toxic airemissions are the two main areas whereOSHA and EPA regulations andresponsibilities tend to overlap. Employeeshave gained rights that ensure them a safe,healthy and hazard-free work-place, while thepublic outside seek protection provided by EPAair quality regulations. Employee health andsafety legislation drives the control of potentiallytoxic air emissions from welding operations inthe shipbuilding environment. OccupationalSafety Health Agency (OSHA) was formed tooversee the prevision of safe and healthy



working conditions for both employers andemployees. Operating within the Department ofLabor, OSHA sets federal guidelines for,among other things, safe concentrations ofvarious toxic substances, defining them as“threshold limit values” (TLV's). Employers arelegally mandated to reduce work-placehazards, implement programs aimed atpromoting job safety and good health to meetall OSHA standards. OSHA laws andregulations concerning indoor air pollutioncontrol concentrate on air contaminants insidecommercial and industrial buildings. Theshipbuilding industry has a wide variety ofindustrial buildings, ships, and work spaceswhere air quality must meet OSHA air qualitystandards to ensure a safe workingenvironment. The laws establish threshold limitvalues (TLV's) and permissible exposure Iimits(PEL’s) for over 500 regulated substances.Several of these substances are routinelyfound in shipyard industrial manufacturingoperations that may, through either short orlong term exposure, create unsafe workingenvironments.

OSHA General Industry Safety Order (GSIO)5150, 1536 & 1537 require the use of localexhaust hoods, if possible, for all indoorwelding and cutting of stainless steel. Sourcecapture is thought to be essential forcompliance with this regulation, although thismust be determined on a case-by-base basisin every shipyard. Currently, there is pendingOSHA legislation, which if passed andimplemented, employers may be required toachieve compliance by engineering controls orface immediate legal action. OSHA’s newestStandads set employee/worker exposure Iimitsto toxic and hazardous air contaminants asfollows

(1) Time Weighted Average (TWA) IExposure Limit:The employee’s average airborne exposure inany 8-hour work shift of a 40-hour week shallnot be exceeded. Measurement is quantifiedfor particulate in milligrams (mg) ofcontaminant per cubic meter (m3) of air in theworker’s breathing zone.

(3) Maximum Exposure Concentration:The employee’s exposure which shall not beexceeded during any part of the work day. Ifinstantaneous monitoring is not feasible, thenthe ceiling shall be assessed as a 15-minutetime weighted average.

Some of the newly-regulated substances underrevised standardis include:

Contaminant I 8 hrTWA

Aluminum Dust (respirable taction) 5.0Cement Dust (inspirable fraction) 5.0Welding Fume (total particulate) 5.0(Oil Mist 5.0Carbon Black 3.5Wood Dust (all soft and hard 2.5except WRC)Copper Fume 0.1

Concerns over dean air in the industrial work-place are frequently well founded and animportant issue for shipyard management andshipyard unions. Airborne contaminants(particulate dusts, fumes, mists) common toshipyard industrial settings contain potentiallycarcinogenic agents and contaminants that can



cause reproductive harm. Many substancesare currently being examined for suspectedcauses of cancer and a variety of otherillnesses. The list of regulated substances isincreasing and the exposure limits areconstantly under evaluation and beingreduced.

1.6 Hexavalent ChromiumWhen welding with electrodes containingquantities of chromium (i.e. stainless steelelectrodes), the arc vaporizes some of the fillermetal and the emissions will contain smallquantities of hexavalent chromium (Cr+6), alongwith a wide variety of other substances.Hexavalent chromium is a substance governedby OSHA and EPA regulations that are morestringent than those for other weldingemissions due to the potential carcinogeniceffects.

Hexavalent chromium is a human carcinogenand is one of the most toxic forms of metalfound in commonly used industrial compounds.Many environmental and health groups arepushing to increase regulation to protectworkers and the environment/public health.Currently, environmental and health groups,along with unions, are supporting a severereduction in the PEL for Cr+6. OSHA hasrecently denied a request for an emergencytemporary standard (ETS) for Hexavalentchromium, but has vowed to draft a proposedregulation by early 1996. OSHA is compilingfeasibility and health assessments for rule-making. They have also spoken with industrualorganizations such as the Chrome coalitionand have drafted a list outlining the demandsfor the rule-making.Many variables drive the development ofhexavalent chromium and other potentiallytoxic particulate within the weldingenvironment The size of the work piece, weldtime, amperage, hours of operafion, type of

shielding, and several other factors affect thegeneration of Cr+6. Hexavalent chromium andother potentially toxic emissions will bediscussed in more detail in Chapter 4.

1.7 List-of-lists and Summary:Welding rods, electrodes, and wires containmany substances that are regulated by EPAand OSHA laws. Table 1 itemizes the majorityof substances that are potentially present inshipbuilding electrodes. The last column inTable 1 presents a letter that corresponds tothe regulation that each substance isregulated. Table 2 is the regulatory list referredto in the last column of table 1. The list ofregulations contains the following: 5 FederalEPA regulations, 3 Occupational Healthregulations, 3 California EPA air qualityregulations, and 5 miscellaneous state andfederal regulations. All of the constituents withinthe weld rod (Table 1) have the potential tobecome an airborne emission.

1.8 Summary:In summary, increasing environmental andoccupational health regulations concerningwelding fumes and particulate is a concern forshipyard management throughout the nation.Strict environmental legislation in the form ofthe 1990 Clean Air Act Amendments Title Vpermiting and Title Ill Hazardous Air Pollutants(HAP's) will require that emissions from weldingand cutting operations be addressed. Asregulations become more stringent andstructured, air quality districts will haveincreased power to regulate the way industrynormally conducts business. Similarly, OSHAregulations are becoming more stringent withrespect to indoor air quality and employee toxicexposure.

Characterizing Shlpyard Welding Emissions and Associated Control OptionsPage 1-5

Chapter 2. Shipyard Welding Operations

2.1 Introduction to Shipbuilding MaterialsThe structural frame-wok of most ships isconstructed of various grades of mild and highstrength steel. Steel provides the formability,machineablity, and weldability required,combined with the strength needed for oceangoing vessels. Various grades of steelpredominate most ships, although aluminumand other nonferrous materials are used forsome superstructures (deck-houses) and otherspecific areas within the ship. Other materialsfound on ships, like stainless steel, galvanizedsteel, and copper nickel alloy, are used for avariety of corrosion resistant purposes andstrutural integrity. Although, nonferrousmaterials are used in far less quantity thansteel. Shipboard systems (i.e. ventilation,combat, navigational, piping, etc.) are usuallywhere the more “exotic” materials are used.These materials are required to perform a widevariety of functions including the shippropulsion systems, backup power, kitchens,pump stations for fuel transfer and combatsystems.

Steel used for constriction can be subdividedinto three types: mild, high-strength, and highalloy steel. Mild steels, have valuableproperties and are easy to produce, purchase,form, and weld. On the other hand, high-strength steels are mildly alloyed to providemechanical properties that are superior to themild steels. Extremely high-strength steelshave been developed specificaliy for use innaval construction. in general, the highstrength and high yield steels are called HY-80,HY-100, and HY-130. They have strengthproperties in excess of the commercial gradehigh strength steels. Welding processes aremore complicated for highstrength steels inorder to prevent deterioration of theirproperties. Specific weld rods are needed forhigh-strength steel and weld joint heating(preheating) is usually required. A third generalclass of steels, the high-alloy steels, are madeby including relatively large amounts of alloying

elements, such as nickel, chromium, andmanganese. These steels, which includestainless steels, have valuable conusionresistance properties and also require specialwelding processes.

Steel is an excellent material for shipbuildingpurposes and the choice of welding electrodeis critical in all welding applications duringconstruction. The standard goal is to obtain aweld with equivalent strength charactenstics tothe base metal. Since minor flaws are likely tooccur in production welding, welds are oftendesigned and welding electrodes chosen toproduce welds with properties in excess ofthose of the base metal.

Aluminum has found increased application asa shipbuilding metal due to its high strength-to-weight ratio compared to steel. Although theuse of aluminum for hulls has been limited,aluminum superstructures are becoming morecommon for both naval and merchant shipconstruction. Vessels solely made fromaluminum are primarily smaller size boats, suchas fish boats, pleasure boats, small passengerboats, gunboats, and hydrofoils. The aluminumused for shipbuilding and repair is generallyalloyed with manganese, magnesium, silicon,anti/or zinc. These alloys offer good strength,corrosion resistance, and weldability.

2.2 Common Welding ProcessesShipyard welding processes, or m o r especifically fusion welding, is performed atnearly every location in the shipyardenvironment. The process invoives joiningmetals by bringing adjoining surfaces toextremely high temperatures to be thsedtogether with a molten filler material. A heatsource is used to heat the edges of the jointpermitting them to fuse with molten weld fillermetal (electrode, Wire or rod). The requiredheat is usually generated by an electric arc or agas flame. Shipyards choose the type ofwelding process based on

Characterizing Shipyard Welding Emissions and Associatad Control OptionsPage 2-1


specifications, prodution rates, and a varietyof operating constraints. For commercialshipbuilding, welding processes are subject toreview and approval by the regulatory bodiesof the United States Coast Guard (USCG)and/or the classification societies of theAmerican Bureau of Shipping (ABS). In U.S.practice, most oversight and inspection ispetiormed by the ABS, operating under amemorandum of understanding with theUSCG. The ABS Rules for Building andClassing steel vessels contains a section onthe required procedures and practices ofwelding for hull construction and outfitting.Similar standards and requirements have beenestablish by the U.S. Navy for naval shipconstruction, repair, and modification.Standards for military vessels are usually morestringent than commercial vessels.

An important factor with respect to the fusionwelding processes is arc shielding to protectthe weld pool. The temperature of the weldpool is substantially higher than the adjoiningmetals melting point. At extremely hightemperatures, a reaction with oxygen andnitrogen in the atmosphere is rapid and hasnegative affects on the weld strength. Shouldoxygen and nitrogen from the atmospherebecome trapped within the weld metal andmolten rod, embrittlement of the weld area willloccur. To protect against this weld impurity andensure weld quality, shielding from theatmosphere is required. In most weldingprocesses, shielding is accomplished byaddtion of a flux a gas, or a combination of thetwo. Where a flux material is used, gasesgenerated by vaporization and chemicalreaction at the electrode tip, result in acommbination of flux and gas shielding thatprotect the weld from nitrogen and oxygenentrapment. Shielding wilI be discussed in thefollowing sections as specific weldingPrecesses are described.

In electric arc welding, a circuit is createdbetween the work-piece and an electrode orwire. When the electrode or wire is held a shortdistance away from the work piece, a high-temperature are is created. This arc generatessufficient heat to melt the edges of the workpiece and the tip of the electrode or wire toproduce a fusion welding system. There are anumber of electric arc welding processessuitable for use in shipbuilding. All processesrequire shielding of the weld area from theatmosphere. They may be subdivided into flux-shielded and gas-shielded processes.

Manufactures of welding equipment andassociated consumable and non-consumableproducts report that arc welding withconsumable electrodes is the most universalwelding processes. The percentage ofconsumable electrodes purchased by all weldrod users in 1991 were distributed as follows:

Table 2.1 Welding Industry PurchaseBreakdown in 1991

Welding Process %

Shielded Metal Arc Welding (SMAW) 45Gas Metal Arc Welding (GMAW) 34Flux Core Arc Welding (FCAW) 17

Submerged Metal Arc (SAW) 4

Table 2.2 National Steel and Shipbuilding1991 Breakdown

Welding Process %Shielded Metal Arc Welding (SMAW) 47Gas Metal Arc Welding (GMAW) 8flux Core Arc Welding (FCAW) 40Submerged Metal Arc (SAW) 5

It is expected that this proportionality isshipyard and construction project specific.

Characterizing Shipyard Welding Emissions and Associated control OptionsPage 2-2


2.2.1 Shielded Metal Arc Welding (SMAW)Flux-shielded electric arc welding processesare distinguished primarily by their manual orsemi-automatic nature and the type ofconsumable electrode used. The SMAWprocess utilizes a consumable electrode (12 to18" in length) with a dry flux coating, held in aholder and fed to the work piece by the welder.The electrode consists of the solid metal fillerrod core, made from either drawn or castmaterial covered with a sheath of metalpowders. SMAW is also frequently refereed toas “Stick Welding” and “ARC Welding”. Theelectrode metal is surrounded by flux that meltsas welding progresses, covering the depositedmolten metal with slag and enveloping theimmediate area in an atmosphere of protectivegas. Numerous electrodes are available, asclassified by the American Welding Society(AWS). The choice of eleotrode is base on theABS or Miliitry Specification that are based onthe required composition and properties of thedeposited weld metal and strengthrequirements of the structure.

Table 2.3 Advantages and Disadvantages of

Manual SMAW may be used for downhand(Flat), horizontal, vertkal, and overheadwelding. SMAW processes may also be used

Figure 2-1 Diagram of SMAW WeldingProcess

semi-automatically through the use of a gravitywelding machine. Gravity machines use theweight of the electrode and holder to producetravel along the work piece.

2.2.2 Submerged Arc Welding (SAW)Submerged arc welding (SAW) is another flux-shielded electric arc welding process used inmany shipyards. in this process, a blanket ofgranulated flux is deposited on the work piece,followed by a consumable bare metal wireelectrode. Generally, the electrode serves asthe filler material, although is some cases metalgranules are added to the flux. The are,submerged in the blanket of flux, melts the fluxto produce a protective insulated molten shieldin the weld zone. High heat concentrationpermits heavy weld deposits at relatively highspeeds. After welding, the molten metal isprotected by a layer of fused flux which issubsequently removed and may be recovered.

Characterizing Shipyard Welding Emissions and Assoclated Control OptionsPage 2-3


Table 2.4 Advantages and Disadvantages ofSAW Welding Processes

Submerged arc welding must be performeddownhand and is ideally suited to butt weldingplates together on panel lines, platen areas,and erection areas. The SAW process isgenerally fully automatic and mounted on amoving carnage or self propelled platform ontop of the work-piece. Since the SAW processis primarily automatic, a good portion of time is

Figure 2-2 Diagram of SAW WeldingProcess

spent aligning the weld joint with the machine.Similarly, the SAW arc operates under acovering of granulated flux, the fumegeneration rated (FGR) or fume formation rate(FFR) are low and will remain constant undervarious operating conditions provided thatthere is adequate flux cover.

2.2.3 Gas Metal Arc Welding (GMAW)A second major category of electric arc weldingare the gas shielded processes. Theseprocesses generally use bare were electrodeswith an externally supplied inert active, or acombination of inert and active shielding gases.The first type of welding process is called gasmetal arc welding (GMAW) or it is commonlyreferred to as metal inert gas (MIG) welding.GMAW uses a consumable automatically fedsmall diameter Wire electrode and gasshielding. GMAW is the answer to a long-sought method of being able to weldcontinuously without the interruption ofchanging electrodes, which necessitated anautomatic wire feeder. A wire spooling systemprovides the electrode/wire filler rate that is at aconstant speed or the speed fluctuates with avoltage sensor. At the point where theelectrode meets the weld arc, an argon orhelium being used as the shielding gas issupplied by the welding gun. It was found thatfor welding steel, a combination of CO2 and/oran inert gas could be used. Often, acombination of the gases is used to optimizecost and weld quality.

Table 2.5 Advantages and Disadvantages ofGMAW Welding Processes

—

Advantages GMAW Disadvantages GMAW

Characterizlng Shipyard Welding Emissions and Associated Control OptionsPage 2-4


Table 2.6 Advantages and Disadvantages

Figure 2-3 Diagram of GMAW Welding Process

2.2.4 Gas Tungsten Arc WeldingAnother type of gas shielded welding processis the gas tungsten arc welding (GTAW) orsometimes referred to as tungsten inert gas(TIG) welding, or the trade name Heliarcbecause helium was initially used as theshilding gas. This was the first of-the "new"welding processes, following stick arc by about25 years. The arc is generated between thework piece and a tungsten electrode, which isnot consumed. An inert gas, usually argon orhelium, provides the shielding and provides fora dean low fume process. Also the TIG weldingprocess arc does not transfer the filler metal,but simply melts the material and the wire,resulting in a cleaner weld. TIG welding is mostoften employed in shipyard for weldingaluminum, sheet metal, small diameter pipesand tubes, or to deposit the first pass on amulti-pass weld in larger pipe and fittings.

2.2.5 Flux Core Arc Welding (FCAW)Flux cored arc welding uses equipment similarto GMAW in that the Wire is fed continuously tothe arc. The main differances is that the FCAWelectrode is a tubular electrode wire with a fluxcore center that helps with Iocalized shielding inthe welding environment. Some flux cored wireprovide adequate shielding with the flux core

Characterizing Shlpyard Welding Emissions and Associated Control OptionsPage 2-5


alone. However, many FCAW processes usedin the shipbuilding environment require theaddition of gas shielding for the qualityrequirements of the shipbuilding industry (i.e.ABS and the NAVY).

Table 2.7 Advantages and Disadvantages ofFCAW Welding Processes

Advantages DisadvantagesFCAW I FCAW

Large single pass Weld spatter can clogfillets possible gas nozzlesTolerant of mill scale Slag coating must be

removedAll position welding Bulky equipmentwith excellent causes accessibilityproductivity problemsLess joint prep. than Equipment isfor SMAW & GTAW expensive

The FCAW process provides a high qualityweld with increased production rates andwelder efficiency over the traditional SMAWprocess. The FCAW process allows for a fullrange of versatility with productionrequirements such as overhead and verticalwelding. FCAW electrodes tend to be a littlemore expensive then SMAW materials

igure 2-5 Diagram of Flux Core Wire

although, in many cases, increased quality andproductivity are worth the investment.

2.2.6 Plasma-Arc Welding (PAW)The last of the shielded gas welding processesis plasma metal inert gas welding (PAW). PAWis very similar to the GTAW process exceptthat the arc is forced to pass through arestriction before reaching the work-piece. Theresult is a jet stream of intensely hot and fastmoving plasma. The plasma is an ionizedstream of gas that carries the arc, which isgenerated by constricting the arc to passthrough a small orfiice in the toroh. Plasmametal inert gas welding results in a moreconcentrated, high-temperature arc and thuspermits faster welding. Aside from the use ofthe orifice to accelerate the gas, plasma metalinert gas welding is identioal to TIG welding,using a non-consumable tungsten eleotrodeand an inert gas shield as displayed in figure2-7.



Figure 2-7 Diagram of Plasma Arc Process

Table 2.8 Welding SMAW GTAW GMAW PAW FCAW SAWProcess Comparison

MatrixDeposition Rate Fair Poor Good Good Good ExcellentField Work Excellent Poor Fair Poor Excellent FairEquipment Maintenance Low Low Medium Medium Medium MediumSmoke/Fume High LoW Medium Low High Very LowGenerationVariety of Metals Sat Excellent Good Good Good FairWeldability

Plasma-arc welding is generally manual andhas minimal use in shipbuilding although it issometimes used for flame sprayingapplications. Plasma arc is used primarity forsteel cutting in the shipbuilding environmentTable 2.8 provides a comparison of the majorwelding processes. Each process has its ownset of applications due to the constrmintsoffered by the process.

2.2.7 Gas Welding, Brazing and SolderingGas welding employs heat generated by theburning of a gas fuel and generally uses a fillerrod for the metal deposited. The most commonfuel is acetylene, used in combination withoxygen (oxyacetylene gas welding). A hand

cableways, and for brazing or soldering.ldentical or similar equipment is used for cuttingas will be described in a further section.

Soldering and brazing are techniques forbonding two metal surfaces without melting theparent metal. A liquid is made to flow into andfill the space between the two surfaces thensolidfy. If the temperature of the filler metal isbelow 450 C, the process is called solderingand if it is above 450 C, the process is calledbrazing. Soldering is commonly done usingsoldering iron, by flame heating, resistanceheating, or induction heating. On the otherhand, brazing includes the use of flameheating, resistance heating, and induction



heating. Brazing may also be done by dippingparts in a bath. Soldered and brazed productsjoints do not have strength properties that areequivalent to welded joints. Consequently,brazing and soldering find limited application toshipbuilding and repair except for primarilysmall diameter pipe joints, sheet metalfabrication, small infrequent joiner work andmaintenance functions.

2.2.8 Other Welding ProcessesThere are additional types of welding that maybe used in the shipyard environment in smallquantities for a varity of reasons. These areelectroslag, electroslas, thermite, laser, electronbeam and stud welding. Eleotroslag weldingtransfers heat through molten slag, which meltsthe work piece and the filler metal. Although theequipment used is similar to that used forelectric arc welding, the slag is maintained in amolten state by its resistance to currentpassing between the electrode and the workpiece. Therefore, it is a form of eleotricresistance welding. Often, a cooled backingplate is used behind the work piece to containthe molten pool. Another process, electrogaswelding, employs a similar setup but uses a fluxcoated electrode and CO2 gas shielding. Bothof these processes are very efficient forautomatically making vertical butt welds andare highly advantageous for thicker plate.These techniques are expected to receiveconsiderably wider application in shipbuilding.

Laser welding is a new technology which usesa laser beam to melt and join the work piece.Although the feasibility of laser welding hasbeen proven, cost has prevented itscommercial application to date. The potentialfor efficient high quality welding may makelaser welding an important technique forshipbuilders in the future.

Another relatively new welding technique iscalled electron beam welding. The weld is madeby firing a stream of electrons through an orificeto the work piece, which is surrounded by aninert gas. Electron beam welding does notdepend on thermal conductivity of the material tomelt the metal. Consequently, both lower energyrequirements and reduced metallurgical effectson the steel are significant benefits of thistechnique. As with laser welding, high cost is amajor problem.

Stud welding is a form of electric arc welding inwhich the stud itself is the electrode. A studwelding gun holds the stud while the arc isformed and the plate and stud end becomemolten. The gun then forces the stud againstthe plate and the stud is welded to the plate.Shielding is obtained by the use of a ceramicfirrule surrounding the stud. Stud welding is asemi-automatic process commonly used inshipbuilding to faciliite installation of non-metallic materials, such as insulation to steelsurfaces.

Thennite welding is a process that usessuperheated liquid metal to melt the work pieceand provided filler metal. The liquid metalresults from a chemical reaction between amelt oxide and aluminum. The liquid metal ispoured into the cavity to be welded and thecavity is surrounded by a sand mold. Thermitewelding is somewhat similar to casting and isprimariiy used to repair castings, forgings or toweld large structural sections such as a stemframe.


Chapter 3. Welding Fume Collection and Filtration Technologies

3.1 IntroductionThis section of the report provides anintroduction to the variety of weld fumecollection and filtration technologies andcommercially available equipment. Theadvantages and disadvantages of mechanicaland electrostatic filtration technologies areinvestigated and analyzed with respect tomaintenance, durability, and filtration efficiency.Weld fume collection equipment configurationsare analyzed with respect to their applicabilityto the shipyard operational environment andproduction process areas. Appendix 1 providesthe results of investigations and research aboutshipbuilding processes and facilities. Theinvestigations serve as the basis fordetermining collection variations that could beapplied in the shipyard Developing genericcollection configurations for the shipbuildingenvironment is a very diffcult task and them isno single configuration that can be appliedthroughout the shipyard. Shipyards have anextremely diverse set of facilities andproduction constraints. Each Shipyard facility,area, and production process must be handledon a case by case basis when addressing weldfume collection and filtration.

3.2 Current Filtration Technology Emissions EquipmentOne solution for reducing welding emissionreleases from shipyards is through the use ofcollection and filtration equipment Fumescreated during welding operations generallycontain particulate in the sub-micronic range(i.e. 0.01 -1.0 microns in diameter) and thePM-10 range (<10 microns), which requiresspecialiied filtration equipment. A micron is onmillionth of a meter.

There are essentially two major categories offiltration technology that can be applied to sub-micronic weld fume/dust particulate emissions.The first is electrostatic precipitation (ESP) andthe second involves a variety of mechanical

media filters. A discussion of welding emissionparticles and filtration efficiency rating ispresented prior to a more indepth presentationabout mechanical and electrostaticprecipitation filtration technologies.

Airborne “particles” can be in the form ofsmoke, weld fumes, mist fumes, dust aerosolsand vapors. Separation of particulate from theindustrial airstream is referred to as filtration.Particles can be very small and are generallyonly visible when they are present in denseconcentrations such as experienced near theare of welding operations. It is diffcult to tell ifsmall particles present in high concentrationsare suspended in air (as particles) or diffusedthroughout as gas or vapor. Although, themajority of welding metal emissions ofenvironmental concern are treated asparticulates. The lower size boundary whereparticulate act as true particles is about 0.01microns. Normal methods of collection,separation, and filtration do not generally applyto particles smaller than 0.01 microns andremoving them from industrial process airrequires technologies used for gaseousmaterials, which will not be discussed in thisreport. Particulate above 0.01 microns areconsidered to be filterable and can beaddressed with electric and mechanicalcleaners.

3.2.1 Efficiency Rating SystemsEfficiency rating systems need to beunderstood with respect to air filtrationefficiency and co!lection efficiency. Filtrationefficiency is a function of how well the filterperforms air cleaning and particle removal,while collection efficency refers to thepercentage of the smoke/fumes generated bythe arc that are captured by the system anddirected through the filter.

Collection efficiency is easy to understand. if awelding hood and ducting system is located



directly above an emission source, 100%collection efficiency can be achieved. Forexample, if there is no place for the fumes toescape, 100% collection is achieved.Extremely high collection efficiencies arediffilcult to achieve and in many cases,collection efficiency WiII be a function of howdiligent welders are at ensuring that thecollection hood is placed over the welding arc.

Filtration efficiency, on the other hand, is amore confusing concept to comprehend and tospecify. Filters are designed for efficiencies forvarious sized particles. For example, somemedia filters are 98% efficient at filteringparticles down to 0.3 microns, while other fittersmay be 90% efficient at filtering particlas downto 0.01 microns. Therefore, filtration effciency isdependent on the particulate size specified andparticle size must be taken into account whenspecifying efficiency needs. it is also importantto note that sometimes filtration efficiency willbe reduced as the filter becomes filled withParticles.

3.2.2 Electrostatoc Precipitators (ESP)Electrostatic preapitators (ESP) or sometimescalled electronic air cleaners areused to filter air pollutants in therange of 10 microns or smaller.To understand the theory ofelectrotatic precipitation andpariticle attraction, think of staticelectricity and a positively chargedcommon hair comb attractingsmall bits of paper. The exampleillustrates the attracting forceemployed in electronic aircleaners and the particulate thatpasses though. Under normalcondtions, particles in the air tendto be neutrally changad. Anelectronic air cleaner alters theelectrical balance of particles inthe air by providing a high positive

charge that causes the particles to attract to acollector plate as displayed in figure 3.1.

High efficiency two-stage electrostaticprecipitators are generally designed to filter andcollect particles down to 0.01 microns, such asthose associated with industrial oily smokesand metal fumes from welding operations. Atwo stage electronic precipitator is composed oftwo sections; a charging section (ionizer) and acollection plate section as displayed in figure3.1. The first section contains a series of Wassuspended between metal plates that chagethe particles as they pass through. Thecollecting section consists of a series of parallelflat metal plates, spaced spat with alternateplates that are charged and grounded.Particles are driven by a repelling force fromthe charged plates toward the ground plates towhich particles will be collected. The exactconfiguration of the ESP system will vary fromone company to another, but the basicoperation is based on the same principals.

Many electronic air cleaner systems containsome type of mechanical pre-filter. Heavy-duty,reusable, mechanical filters serve to aid in the

frequently air distribution across the face of the

Figure 3-1 Electronic Precipitator Flow Diagram (Micro Air)


electrostatic units and to remove largeparticles. Pre-filtration and associated capturingof large particles extends the operational Iife ofthe electrostatic portion of the filter. Without apre-filter, electrostatic precipitators can becomeoverloaded with larger contaminants and arcthe precipitator, causing severe reductions infiltration efficiency.

As particles buildup on the plates, filtrationeffciency drops and the plates becomesaturated with particles. Particle buildup causesthe ESP system to need cleaning andcontinuous maintenance. Most ESP filtrationsystems require a manual cleaning andmaintenance progrom. The type of cleaningmethod employed will be largely a function ofthe contaminants collected and individualprefmnce. There are four basic methods ofmanual ESP maintenance cleaning: 1) hotdetergent bath, 2) cold soak 3) high pressurespray, and 4) automatic parts washer cleaning.Hot detergent bath cleaning is the most widelyrecommended method and with the properdetergent selection, will quickly remove mostwelding emission contaminants collected in theprecipitator. The cold soak method is moretime consuming and is less effective on toughcontaminants. High pressure spraying is ahighly effective method of cleaning, especially ifwarm water and detergent is used. Care mustbe taken to ensure that all plates andcomponents as well as insulator surfaces arecleaned. Automatic parts washers may bedesigned to perform the cleaning asnecessary.

Automatic cleaning systems are provided bysome manufactures of electrostaticPrecipitators, although this does not eliminatethe need to perform manual maintenancecleaning. Most manufacturers of ESPequipment provide maintenance cleaningservices and/or programs. Also, all wastewaterassociated with the ESP cleaning process

must be disposed of properly within theguidelines of local, state, and federalregulations.

3.2.3 Mechanical Filtration DevicesMechanical filtration systems serve as anexcellent method for filtration of weldingemissions. Many mechanical filters use pleatedpaper or polyester filter cartridges to dean orfilter air that flows through. In many cases,standad mechanical filtration systems are thepreferred choice to dean a wide variety ofindustrial, as well as, residential dusts in therange of 1 micron and larger. Also, in recentyears, high efficiency mechanical media filtersare becoming very popular for smaller particlesizes and in some cases, are highly efficientdown to 0.01diameter.

The approach tothe ESP section

microns in aerodynamic

pre-filtration as discussed inis also primarily used when

applying mechanical filters to industrial airstreams that require removal of very smallparticles. Pre-filtration stages are generallyused to provide a systematic reduction in thesize of particles being filtered.

Mechanical filters are designed primarily for“dry” industrial dusts and smokes, but somepre-filters tolerate a minimal amount ofmoisture in the air. Excess fluids of any type inthe air stream can lead to failure of mechanicalfitters due to the plugging of the fitter media.Excess moisture will lead to a reduction incollection flow-rate, which leads to a reductionin fitter Iife. Pre-filters can be used to collect themajority of moisture and larger particlesdeveloped in welding operations.

Most mechanical media filters are disposable,although, some media filters can be cleanedand recyded 2 or 3 times by outside servicesprior to disposal. The cost of the mechanicalfitter insert and the cost of cleaning will drive the



need to replace the unit or have it cleaned. 3.2.3.1 Media Bag FiltersSimilarly, the cast of mechanical filters is Media bag filters are frequently used in dustgenerally a function of their efficiency, particle collectom and are a tubular bag or cube designsize being filtered and the overall size of the as displayed in figure 3-3. These filtrationunit. Figure 3.2 provides an illustration of a devices are highly effcient for collecting fibrousgeneric-mechanical filtration system. and other large- size process particulate at

relatively high concentrationlevels and flow rates.Although they generally willhave little application to weldfume filtration, bag filterscould be used as a pre-filterin Iarger volume applications.

3.2.3.2 Cartidge FiltersCartridge filter elements aregenerally cylindrical in shapeand are very popular farapplications involving weldfume filtration and dustcollection. The cartridge fitterelements are frequentlycleaned on-line with areverse pulse of air Pressure

pressure drop across the filter media, allowinga constant flow-rate for particulate capture.Some cartridge units offer high filtrationefficiency and are capable of trapping up to99% of sub-mioronic (0.01 to 1 micron)materials and virtually 100% of larger dustpartiicles (1 to 100 miorons or larger). Cartridgefilters are sometimes used as a pre-fitter to ahigh efficiency filter or are of high enoughefficiency to serve as a final filter. Exactefficiency of the filtration systems are notstandardized and will vary from manufacturerto manufacturer. Many systems that employcartridge filtration are sized at the factory forspecific system applications.



3.2.3.3 High Efficiency V-Bank Media 3.2.3.4 HEPA filters 99.97 % EfficientFiltersV-Bank or V-Bag filters are highly efficientbag-type filters designed for smaller particlesizes. They are more efficient than standardbag fitters but generally less efilcient than EPS or high efficiency mechanical media filtersystems. V-bag filters can exhibit efficiancies ofaround 95% at 0.3 microns depending on themanufactrer. V-bag filters are disposable andcan be used in conjunction with a Iowerefficiency pre-filter to prolong its Iife and as apre-filter to a higher efficiency filter. For clean-room and very small particle tiltering needs, aHEPA filter or EPS system should follow thehigh efficiency V-bank

HEPA otherwise known as High EfficiencyParticulate Air Filter are widely used in deanroom environments and other applications thatrequire small paiticle size filtration. HEPAfiltration is a relatively new technology inrelation to electrostatic precipitation. As withmost mechanical filters, HEPA grade filters aremade from pleated fiberglass sheets and areover 99% efficient down to .01 microns. HEPAunits are more expensive than pre-filters andwill become dogged easily if large particlesenter the filter fabric It is very important that aseries of pre-filters be used with the HEPA filterto extend their Iii and reduce maintenancecosts.



3.2.4 Filtration Selection (Mech. Vs. EPS)Depending on the type and size ofcontaminants and concentration levels ofairborne particulate, filtration systems may betwo-stage, time-stage, or multiple stage. Eachstage will contain a filtration device that isdesigned to capture various sized particles. Inthe airflow pattern, large paticlee and fibers arecollected by the pre-filters and the final fitter Willcollect the remaining small particulate. Mostwelding time filtration systems WiII need atleast a two stages. The two-stage configurationconsists of a pm-filter and final filter withselected efficiencies for the specific application,size of particle and effiency desired. Three-stage filtration consists of a pre-filter,intermediate filter, and a final filter module,which may consist of a 99.97% at 0.1 micronHEPA or an ESP system for small sizedpartocle applications. Both electrostaticprecipitation and high efficiency mechanicalfiltration technologies can be utilized along withV-Bank cartridge and other pre-filters for acomprehensive multi-staged filtration system.From the previous analysis, it can bedetermined that a high efficiency HEPA or anelectrostatic precipitor (ESP) filter in serieswith pm-filters are the current alternativesavailable. Two of the main issues whencomparing EPS systems and mechanicalHEPA final filtration are the overall reliability

and efficiency of the filters and the requiredmaintenance program and associated issues.

Arc welding produces emissions with a widerange of particle sizes. In an ESP filter, largerparticles and/or prolonged usage of the fitterwill cause bridging across the collection plates,resulting in a reduction in efficiency and a needfor continued maintenance and cleaning. Thebridge across the plates disables the filtrationprocess. With ESP systems, the fan keepscollecting emissions and discharging them intothe local air-space, even if the filtration systemis not filtering adequately. The operator mustconstantly monitor the readings of the filtrationunit to ensure that it is operational andperforming effcient filtration as needed. On theother hand, when the HEPA filter becomes full,there is a pressure drop that reduces the abilityof the collection device to perform its functionby reducing collection velocity. In other words,HEPA filters do not lose their effiency, theyare slowly dogged and the flow-rate of thecollection unit is reduced. Therefore, once thewelder notices that the weld fumes are notbeing collected, the filter must be changed.HEPA filters need to be changed once they arefull, which is most likely accomplished by theoperator/welder. Much of the Iiteratureresearched and reviewed favored the use ofmechanical filters (pre-fiiters with HEPA) overthe use of electrostatic preapitation (EPS) formost welding applications.



3.3 Collection Equipment andConfiguration AlternativesThere are essentially two major types ofpotential emission capturing alternativesavailable for collection of weld fumes. The firstand best alternative is source capture (directlyat the point of generation), and the second isnon-source capture. Source capture ispreferred because of the ability to achieve ahigher rate of collection efficiency and theability to keep potentially harmful emissionsaway from the workers breathing area. Sourcecapture units are preferred because they cancapture a high percentage (>90%) ofcontaminants, while unducted/non-sourcecapture systems can offer around 75% to 90%effective capture efficiency. There are a widevariety of manufactuers that produceequipment fur both types of capturealternatives. Applying sourcecapture and non-some capturemethods to the very difficultapplications and industrial settingsoffered by shipbuilding processes,practices, and facilities is discussedin seotion 3.4 of this chapter. Thefollowing section merely providesthe reader with a background ofweld fume collection devices,systems, and configurations.

3.3.1 Source Capture SystemsSource capture is a techniquewhereby emissions, generated byPorcesses, are collected diractly atthe point of generation (i.e. usuallywithin 1 ft of the welding arc). Some

applications where the fumes generatedrepresent significant respiratory or carcinogenichazard to employees working in the vicinity ofgeneration. Figure 3-6 provides an illustrationof a typical source capture system.

Many types of source capture devices (hoods,enclosures, extraction arms, etc.) are designedto capture a high percentage of the fumegeneration if property used. They rely onmovement of air past the generation source ata velocity sufficient to draw the particles to thecapture device. The capture velocity and hooddesign are the basis for all good somecapture design. Capture velocity is a largefactor in determining how close the device (i.e.capture hood) must be to the point of fumegeneration. Similatly, the distance between the

people in the industry refer tosouce capture as ‘local exhaust’. Sourcecapture is the most effective and most widelyrecommended emissions collection methodbecause it draws off contaminants before theypass through the worker’s breathing zone anddisperse into the facilities air stream. Sourcecapture techniques are extrnmely desirable in

collection device and the fume genration pointis also a driving factor in any efficient timecapture system. In fact, the amount of air(CFM) flow-ate required to extract emissions ishighly related to the distance of the hood to thepoint of generation. Therefore, it can be statedthat the capture efficiency drastically diminishesas the point of collection is removed from the



point of generation. Table 3-1. outlines some ofthe guidelines offered by OSHA with respect toflow-rates, ducting diameter, and the distancefrom the source capture device to the weldingarc.

3.3.2 Canopy Capture SystemsIf the weld fume generation area is wellenclosed, the air contaminant has Iittle areathrough which to escape. Therefore, acanopy capture system could be used.Contaminated air is drawn up through the

high percentage of capture. Some effectivehood design methods involve enclosing theoperation completely with curtains and thenproviding access openings as required.Canopy hoods are effective for manyoperations where thermally generatedcontaminants rise rapidly. Canopy systemsshould not be used when workers must bepositioned directly over the welding processbecause the flow of contaminated air couldpass through a worker’s breathing zone.Also, it is recommended that all employeesworking in canopy collection areas wear

hood at high enough velocity to ensure a proper respirators.

Figure 3-7 Typical Canopy Hood Arrangement



3.3.3 Non-Source and Unducted CaptureSystemsIn many industrial work areas, the best wayto capture emission from welding and cuttingoperations is through a non-source orunducted collection system. Unducted aircleaning systems frequently consist of one ormore air cleaning units, positioned in theoverhead plant space, to create a plannedair circulation pattern, as displayed later inFigure 3.8.

When properly designed, this method cleansthe ambient, in-plant, contaminated air.Rather than collecting the fumes at the pointof generation, as performed in sourcecapture systems, unducted systemsconstantly clean the room air stream toremove indoor air contaminants. Unductedsystems will never remove 100% of thecontaminants in the work area and whenpotentially harmful contaminants are ofconcern, employees should wear properprotective respirators.

Source capture systems are therecommended method of air cleaningbecause they capture contaminants beforethey can escape into ambient air andpotentially into the workers breathing zone.However, there are many factors that canmake source capture systems impractical forspecific work environments and applications.For example, a non-source captureunducted system could be the best availableapproach to fume filtration in the five (5)generalized situations presented in Table 3.2

Table 3-2. Potential Reasons for Non-Source Capture:1. Work is performed on large parts and theworker has no fixed operating position,making source capture difficult toimpossible.2. Workers object to hooded systemsbecause of inconvenience. Some sourcecapture systems may require physicalpositioning by the worker. If it is unlikely theworker will perform required positioning, thesystem will be rendered ineffective.3. Areas where several welders are inconfined areas requiring an excessiveamount of source capture hoods andducting. The impracticality can potentiallyescalate to the point that the benefits ofsource capture effectiveness is eliminated.4. Ovehead cranes and other mobilemachinery make ductwork installationimpossible or extremely inflexible.Unducted systems, designed properly, cankeep the indoor air cleaning units out of thecraneways and still achieve effective aircleaning results.5. Floor layout revisions are anticipated andcould result in expensive ductworkmodifications and redesign. Unduotedsystems are fiexible and can work in avariety of configurations.

The objectives of non-source capture are toachieve a substantial reduction in airpollutants throughout the indoor work-placeand thus reduce the amount of toxicemissions released to the environment fromthe wok-place.

Operation of non-source capture systems willvary from application to application. Inoverhead systems, welding and cuttingfumes rise and are diverted into thecollection units air circulation pattern, whichare routed to the air cleaning units. Each unit



outlet “throws” or “pushes” the contaminatedair toward the other units inlet where the airis drawn in and treated.

Self-contained non-source capture unitmounting heights should be from 9 feet to 15feet above the floor, regardless of the roomsceiling height. An air pattern created at thatheight circulates air from both upper andlower spaces. Minor amounts ofcontaminants and gases can be expected torise above the air pattern, which wiII likely becaptured at later time. By consistentlyremoving contaminants from the room,unducted systems prevent build-up andsubsequent contaminant “stacking” ofpollutants down to the floor level. Air quality.control engineers, employed by the multitudeof air filtration manufacture, will help designsystems to meet individual momconfigurations and work environment needs.

3.3.4 Standardized EquipmentConfigurations Available

Indoor air collection and filtration controlequipment are manufactured in a variety ofconfigurations for a variety of applications.For simplicity, collection and filtrationsystems can be divided into self containedfan/filter units and modular systems. Self-contained collection and filtration units arevery popular throughout industry. They aretypically pm-designed arrangement withoptional filtration types and efficiencies. Onthe other hand, many systems are designedin a modular fashion, to customize systemsfor a variety of applications and efficiencyrequirements. The following two sectionsbriefly describe the two general categories ofequipment that manufacturers havedesigned to solve industrial weld fumecollection and filtration problems. After theintroduction of the standardized equipment,

Figure 3-8 Typical Non-Source Capture Arrangement



Section 3.4 idenfies how standardized andmodified equipment could potentially beadapted to shipyard industial settings.

3.3.4.1 Self-Contained Fan/Filter Units

Many types of self-contained fan/filter unitsare available and in many cases, are thesimplest form of industrial weld fumecollection and filtration offered. Systems areavailable with a variety of filters (V-Bank,HEPA, EPS) and remove particles in a widevariety of sizes. The most popular systeminvolves a single collection arm and hoodthat collects fumes and particles at the pointof generation and filter the air as displayed infigure 3.11.

Most systems work by passing contaminatedair through a cabinet with a pre-set filterarrangement. The cleaned air is thenreturned to the work-space. Therefore, if theunit releases treated air indoors, one mustensure that the air is breathable according toOSHA indoor air quality standards. This type

of equipment configuration is available in awide range of source and non-sourcecapture configurations that can be applied todifferent work environments.

Self-contained units range in capacity from300 to 6,000 CFM. The units are suppliedcomplete with their respective filtercomponents and motor/blower drive sets, inself-contained cabinets, made from industrialhigh gauge steel. Accessories and optionscan include automatic filter cleaning systems,inlet and outlet plenums, source capturehoods and arms, pre-filters, main-filters andafter-filters. Self-contained units can be “free-hung”, in a non-source capture configuration,to clean and recirculate difty air, without useof ductwork, hoods, pickups or enclosures.Units can also be directly ducted to thesource of fume development (i.e. the weldingarc). The systems mentioned above canprovide source capture with extraction armsand in many cases, the systems are light,have wheels and are portable.

Figure 3-9 Typical Modular System Configuration


Chapter 3. Welding Fume Collection and Filtrafion Technologies

3.3.4.2 Module Configurations

Equipment is available in modularconfigurations with air volumes ranging from1,000 to 30,000 CFM. These systemsfeature standard components, arranged in amodular design, for customized applications.The modules allow for flexibility in the designand application of collection and filtration tovarious industrial settings The modulesinclude a fan equipment module and avariety of filter sections including: V-Bankfilters, HEPA filters, ESP systems, andothers. The modules are bolted together andarranged for either source or non-sourcecapture. Modular systems can includeoptions such as in-place cleaning systemsand sophisticated diagnostic efficiencyindicator devices. Figure 3-9 provides a goodillustration of a typical modular type system.



3.4 Applicability of Collection Equipment

Shipbuilding and repair processes,operations, and facilities were investigated toevaluate the feasibility of collecting andfiltering welding fumes and particulateemissions. Results from the shipbuilding andrepair process investigations are presentedas Appendix A and serve as the basis ofunderstanding for the feasibility analysis.Shipyards have very unique facility andprocess circumstances that make itextremely difficult to collect weldingemissions at a variety of production locationsthroughout the shipyard. Applying sourcecapture and non-source capture methods tothe various applications and industrialsettings, offered by shipbuilding processes,practices, and facilities is a challenging taskthat can cause production problems and bepotentially expensive.

Several weld fume collection and filtrationequipment vendors were contacted toinvestigate standardized equipmentavailability and determine how theirequipment could be applied to the shipyardapplications. Flexible equipmentconfigurations that could be customized forspecific production situations were alsoinvestigated. There are no simple solutionsto collecting welding fumes in the shipyardenvironment. Similarly, there is clearly, notone single collection configuration solutionthat can be applied to all shipyard areas or toshipyards with diverse facilities andproduction constraints. Each facility andproduction situation must be handled on acase by case basis.

All areas and processes in the shipyard havetheir own unique set of constraints andpotential collection alternatives. Open areas

Table 3-3 Potential Alternatives to Weld Fume Collection

Potential Collection Systems: Potential Area or ProcessApplicable in the Shipyard

1) End of the Line Filtration Shops and welding area booths

I 2) Portable Roll Around Units with 6 to 14 ft. of Arm Shops, welding area booths, someReach open areas, some confined

spaces I3) Portable Vacuum Units Connected to Weld Guns (Up Confine spaces with MIG guns,to 100 ft. of reach from fitter unit) Open areas, some shops

4) “Hand Held" Light Weight Portable Units Small jobs with weld electrodesVacuum/Filtration Units requiring portability

5) Canopy Hood Collection With or Without Curtains Good for cutting machines, some(Area Capture) shop configurations

6) Non-source Capture Modules Confined spaces, some indoorweld stations



such as panel lines, assembly areas, rotaryturntables, and pin jigs pose uniquecollection constraints. Similariy, enclosedareas including pipe shops, machine shops,welding schools, and sheet metal shops,have a different set of collection alternativesavailable. In addition, confined spaces on-board ships and during instruction mayrequire customized equipment andproduction adjustments. Table 3.3 outlinessix (6) potential alternatives derived frommanufacturers and equipment suppliersurveys and shipyard prcoess research andinvestigations. Each of the potentialcollection systems mentioned are describedalong with their operational pros and cons inthe following six sections.

3.4.1 End of the Line FiltrationEnd of the line filtration is a description usedto explain a filtration solution designed forenclosed buildings, with multiple weldstations, where a large filtration unit could beinstalled on an existing fume collectionsystem. Some shipyard shops have, or couldinstall weld exhaust collection systems thatcollect welding emissions from weld stationsand discard the emissions into theatmosphere. Figure 3.10 displayed a typicalmultiple collection system configuration.Multiple station systems are common and

generally in place to capture the fumes anddivert contaminated air from the weldersbreathing area for Occupational Health andSafety (OSHA) purposes. The systems areexcellent for maintaining and otherwisemanaging indoor air quality in workshopswith welding operations, provided thecollection systems are designed and usedproperly. Multiple station collection systemsare applicable to several indoor shipyardshops (i.e. pipe shop, sheet metal shop,metal fabrication, etc.) throughout theshipyard.

3.4.1.1 Operational ProsIn many cases throughout the shipbuildingindustry, a portion of the welding occurs inshops and other enclosed facilities wereemissions are already collected and pulledaway from the welders breathing area. Ifweld stations exist with a collection system, afiltration improvement could be a “bolt-on”solution that does not interfere withproduction operations within the facility.Therefore, this solution alone could minimizea good portion of the facilites toxic weldingemissions. End of the line filtration is anexcellent method to minimize the amount ofweld fume emissions released into theenvironment without filtration. Therefore,welding emissions to the environment will be

I Figure 3-10 Multiple Station Collection Station (AirF/ow Systems Inc.)



minimized to the extent of efficienciesachieved by the collection and filtrationdevices installed. The only major operationalchange is that the filtration unit will need tobe maintained frequently depending on thequantity of material welded, filtration capacity,and the maintenance schedule prescribed bythe manufacturer.

3.1.1.2 Operational ConsThe main problem is that systems requirecontinuous and potentially expensivemaintenance cost for cleaning, replacing anddisposing of filters. This solution will collect alltypes of weld fumes created in theenvironment from which it is associated (i.e.mild steel, copper nickel, stainless steel, etc.)and will not be used exclusively for

potentially ‘toxic” emission sources (i.e.hexavalent chromium). Therefore, themaintenance expense may be greatbecause of the large quantity (Ibs) ofemissions filtered by the system. Therefore, itwould be important to have a less expensiveprefilter arrangement to minimize costs.

3.4.2 Self Contained Roll-Around Units(With 6 to 14 ft. of Arm Reach)Portable roll-around units are widely used forin-door industrial activities because of theiravailability and applicability to many weldingoperations throughout industry. There arenumerous manufacturers of such equipmentand their electrical, physical, mechanical,and operational characteristics vary greatly.The roll-around units are “stand-alone”

Figure 3-11 Self Contained Roll-Around Unit

Characterizing Shipyard WeIding Emissions and Associated Control OptionsPage 3-15


collection and filtration systems with one ortwo collection arms as displayed in figure3.11. The collection hood arms generallyrange from 6 to 10 ft. in total reach. Most ofthe systems are designed and tested andprovide analytical data on their filtration andcollection efficiency rating.

3.4.2.1 Operational ProsThis option works best for collecting fumes atspecific weld stations in shipyard shops andsome outside areas that have smooth floorsurfaces and accessibility. The smaller unitshave less maintenance requirementsbecause they could be used to filter specificpotentially harmful weld fumes (i.e. weldfumes containing Cr6 or Cadmium). Many ofthe roll around units are very efficientcollection and filtration systems. If a shipyard

emissions.3.4.2.2 Operational Cons

The applicability of the roll-around units tothe shipbuilding industry is limited by avariety of operational and physicalconstraints. For the roll around units,portability is limited to areas in the shipyardwith floor surfaces that can handle a 250 to500 lb. cabinet (approx. 5’ X 3’ X 4’) with 6 to8" industrial casters. In many cases, hoses,electrical cords, pot holes, steps, largecracks in the flooring and a variety of otherobjects, will be a deterrent to moving this unitto and from stations that require fumeemission filtration. The extraction armsaverage around 8 ft. in length (availablelength are up to 14’), which tends to beanother drawback that limits the applicabilityof this option to anything but the indoor

controls and directs welding with electrodes shops and some unique outdoor and wires containing potentially harmful applications. Outdoor and indoor areas,fumes to roil-around units, emissions may be where very large workplaces are weldedmitigated. In addition, If the majority of and assembled, provide a challenge to thesepotentially harmful emissions from welding units because of their limited reach andoccurs inside the shops with smooth floors, portability.this alternative is very attractive for reducing

Figure 3-12 Weld Gun Units

Charactaizing Shipyard Welding Emissions and Associated Control OptionsPage 3-16

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Another important operational constraint isthe fact that shipyard management couldneed to direct potentially harmful weldingprocesses to the roll around units or directthe units to the toxic welding locations.Directing specific weld rods, wire andelectrodes to specific locations with weldfume collection machines, would be anoperational constraint to most shipyards.Increased planing, predictability and a highlevel of production control on the part of theshop manager with respect to weldingstations, job-type planning, and specificwelding needs is required.

3.4.3 Vacuum Units Connected to WeldGunsThere are several manufacturers that buildvacuum units that connect directly to MIGtype weld guns (automatic wire feed with gasshielding). Some manufacturers areattempting to design collection systems atthe point of generation near the weld arc forSMAW welding processes with limitedsuccess. Collection hoses on these unitsconnect to the gun and run back to anindividual self contained unit about the sizeof an average arc welding machine asdisplayed in figure 3-12. The units have areach from 25 to 50 ft from the filtration unitand many systems have the ability to handle1 to 4 weld guns. The size and weight arevery similar to the roll around units andfrequently come with casters for mobility. Toeliminate problems with sizing propervelocities and fan motor requirements, it isrecommended that maximum horsepowerunits are best for enjoying the fiexibilityoffered by this type of option.

3.4.3.1 Operational ProsIt appears that this option may be a goodsolution to the problems of ensuring that thewelders are using the collection and filtration

systems because the collection system isattached directly to the weld gun. Forexample, when the units are used correctly,they can collect fumes in several weldingposition (i.e. down-hand, vertical, andoverhead), which is difficult to perform withother types of fume collection. Although,vertical welding is not as efficient with guncollection systems. These systems havegood range abilities for on-board and on-block applications where MIG type guns areused because the filtration unit can beplaced as far as 60 ft. from the welder.

3.4.3.2 Operational ConsOne of the main concerns about this optionis that it is only applied to GMAW automaticwire feed type welding equipment. A goodportion of potentially harmful fumes arederived for SMAW processes and they canalso be a majority of the shipyard emissions.Some work has been devoted to developinga system for the SMAW process with limitedsuccess. The main operational problemshave to do with the weld gun becoming toobulky to perform high quality welding and thedistance from the arc to the weld gun can be14”, at times, requiring a large diameter hosewith very high velocities. Many of the weldersfind the attachment for MIG and SMAW gunsvery bulky, which impairs the weldersvisibility. Therefore, welding with collectionunits connected to the weld guns could yieldreductions in weld quality and overallproduction rates.

3.4.4 Light Weight Portable Vacuum -Filtration UnitsSeveral manufacturers offer light weightportable vacuum and filtration units as asolution to mitigating potentially toxicemissions. The units are essentially avacuum cleaner with an electrostatic cleaneror a mechanical filter. They are applicable toa wide variety of areas in the shipyard and



propose to be a mobile solution to temporarywork station emissions collection needs.These systems come in various sizes andefficiencies and are light enough for one ortwo workers to transport throughoutproduction areas, as needed. The systemsare generally designed with a 2“ to 3“diameter hose with approximately 10 to 25feet of length. Figure 3.13 displays a light

the case. The small portable system are notextremely practical in that they require thewelder to constantly move the unit becauseof the limited amount of reach capabilitiesand positioning of the collection apparatus.The filtering capabilities, durability, andcollection velocities of these systems areessentially exchanged for their light weight.Therefore, application of these systems

weight portable type system. should be considered on a case by case

Figure 3-13 Light Weight Portable Unit

3.4.4.1 Operational ProsSmall portable systems have potential tohelp in areas that are confined and havevery limited amount of welding (i.e.maintenance or small jobs). Their mainstrong-suit for these systems are their lightweight and portability, which-allow them to beused in a wide variety of Iocations in theshipyard These systems could be useful insituations where harmful emissions need tobe captured on an as needed basis.

basis.

3.4.5 Canopy HoodCollection With orWithout Curtains(Area Capture)Canopy hoods areused throughoutindustry, with or Withoutcurtains, to controlemissions from specificprocesses. Canopiesoffer a goodcombination betweensource and non-sourcecapture in that fumescan be collected andfiltered in the canopy or

the canopy can be used as the collectionfunnel for source capture. The systems aremost applicable to continuous operationsoccurring at the same Iocation although,some portable canopy arrangements couldbe designed for a variety of applications inthe shipyard environment. The indoor smallcanopy design applies to shipyards mainly inproduction shops. If a curtain is used, thesystem basically tents the operation andincreases the collection efficiency of thecanopy hood. Canopies may also be

3.4.4.2 Operational Consdesigned to be applied to a variety of large

On the surface, these systems seem as ifoutdoor or indoor applications. The canopies

they could apply to a variety of shipyatrdcould be designed to be portable, for outdoor

cofigurations, although in reality, this is notyard-wide usage, and can be designed inone of the following configurations 1) utilize



non-source capture within the canopy, 2)have a flexible ducting system within thecanopy along with non-source filtration, or 3)as a funnel to extract and filter contaminatedair. Care must be taken with respect toworker protection in these types o fconfigurations.

3.4.5.1 Operational ProsThe canopy alternatives provide acombination of usability and applicability tosome shipyard weld fume collection needs.Indoor canopy systems are good forlocalized work in certain areas of theshipyard shops where source capture isundesirable.

3.4.5.2 Operational ConsAs with many of the options concerning thecollection of specific emissions, shipyardmanagement must understand that thesystem is available and it must be used asnecessary to minimize potential release andprotect employee health. Productionplanning will be required whenever specificjobs must include the addition of weld fumecollection devices in the production process.In some shipyards this could be a realoperational constraint due to a lack ofproduction control. Planning, predictabilityand a high level of production control on thepart of the shop manager is required when itcomes to integrating this type of system intothe shipyard operations.

3.4.6 Non-Source Capture ModulesNon-soure Capture modules werediscussed earlier and have some potentialfor application in the shipbuilding and repairoperations. The units are “stand-alone”, inthat they take in contaminated air from theroom environment, filter the air, and exhaustit back into the room environment. Theexhaust generally causes an air pattern to

direct other fumes back into the intake. Non-source capture modules are available in awide range of sizes and shapes and can bemounted in a variety of locations. Essentially,the systems pull in contaminated air, filter it,and release it. The systems could be appliedto confined spaces or rooms on-board ships.To ensure that employees are protected frompotentially harmful fumes, respirators andother protective equipment should be used.The effectiveness efficiency of the system isdependent on the systems capture efficiency(i.e. percentage fumes being filtered), whichis a function of good design.

3.4.6.1 Operational ProsThe non-source capture systems are mainlystationary and permanent. Although, withsome effort and design, systems could bemade to be portable and applied to confinedspaces (i.e. machinery spaces, stainlessexhaust stacks etc.). The complete systemcould be packaged to be transported byforklift and lifted on ships via cranes. Theweight of the systems range form 350 to 700lb. depending on system configuration andspecific packaging.

3.4.6.2 Operational ConsThe systems are not factory designed to beportable and if they are not setup properly,they can exhibit poor collection efficiency.They may require systems to be designedvertically or with an extraction element thatcould extend to the ceiling to capture andfilter fugitive weld emissions. As with many ofthe options concerning the collection ofspecific emissions, shipyard managementmust use the system maintain it asnecessary to minimize potential release andprotect employee health.


Chapter 4. Arc Welding Emissions Factor Information

4.1 IntroductionAs potentially harmful emissions from electricarc welding operations are becoming anenvironmental issue, the EPA Office of AirQuality Planning and Standard EmissionsInventory Branch, State Air Resources Boards,Air Quality Management Districts, and industryare striving to develop emission factors toquantify emissions. Similarly, OSHA andoccupational health and safetyofficials/representatives, NAVSEA, andindustry are also heavily involved with weldingemissions from the standpoint of the welderexposure levels. At present there is somewhatlimited data available for developing standardemission factors for specific processes andelectrode types. Current technical reports andIiterature contain emission data for selectedrods, electrodes and Wires under limitedvariations in operational settings. In somecases, even the fume sampling protocol isunder scrutiny. Even with the limited data,emission factors have been developed, andthis chapter provides an introduction to themost current arc welding emission factorinformation available.

4.2 BackgroundIn eleotric arc welding, the resulting hightemperature melts the consumable Wire or rodand heats the work-pieces, which enablesfusion and joining of the metal parts. The risingplume of heated air forms a high localconcentration of a complex mixture of gases,oxides, and other metal compound particulatematter (PM). It is generally accepted andvalidated in the technical literature thatanywhere from 0.5 to 3.5 percent of theconsumable welding electrode is converted toparticulate matter (PM) emissions (commonlycalled weld fumes), depending on the processtype. The amount of rod converted to time iscalled the Fume Generation Factor (FGF) orFume Formation Rate (FFR) and is presentedas a percentage fume to rod (Lb. fume / Lb.rod). The quantity and chemistry of the fume is

dependent on the type of welding process,electrode composition, and to a lesser extent avariety of other operational variables such asvoltage, shielding, polarity, and current.

Consumable electrode, rod, and wire materialcomposition are selected to be metallurgicallycompatible with the wok-pieces being joined,which helps ensure proper fusion and strengthof the weld. Throughout the technical Iiterature,it is commonly accepted that vast majority ofthe fume composition is determined by theelectrode. The consumable electrode or wirecomponent is the primary source of the fumebecause the entire rod reaches very hightemperatures at the arc, whereas the weld pooland portions of the materials joined are notbrought to such high temperatures. Therealization and acceptance that weld fumes aredriven mainly by the electrode composition iscentral to the interpretation of data and thederivation of emission factors.

Due to the variety of welding operationalscenarios, welding processes, and electrodetypes, universal emission factors need to bedeveloped for the different processes and theemission constituents of concern (i.e.hexavalent chromium, nickel, lead, etc.). Metalswithin welding rods have different meltingpoints and boiling points. Specific emissionquantities of the metals will depend on theindividual metals’ physical characteristics aswell as welding process variables such as gasshielding or flux coat shielding. At this time,chromium, hexavalent chromium, manganese,lead, cadmium, manganese and nickel are themain metal emissions of concern withenvironmental and health agencies.

Most emissions are treated as very small metalparticulate released into the local air-stream.However, hexavalent chromium is differentEmissions of hexavalent chromium, ascompared to nickel and others, arecomplicated by the fact that a specific valence

characterizing Shipyard Welding Emissions and Associated Control OptionsPage 4-1

Chapter 4. Arc Welding Emissions Factor lnformation

state of chromium is the focus of interest. Theoxidation/reduction reaction rate and chemistrymake the emission rate strongly dependent onthe environment in which the reaction takesplace. It is also interesting to note thathexavalent chromium is relatively unstable asan aerosol in the presence of a number ofatmospheric pollutants. The Research TriangleInstitute (1988) measured the degradationrates in Iaboratoty and field tests, and reportedan average hatf-life of 16.4 hours (+/- 6.9hours). A half-life that is sufficiently short willhave limited effect on the environment Thisfact can be very important when performinghealth risk assessments for the local areasaround which hexavalent chromium is emitted.

4.3 Available Information on Arc WeldingEmission FactorsEmission factors for electric arc welding are inthe early stages of development Limitedemission data is available and form the basisfor deriving general factors to quantifyemissions. This section provides the majority ofarc welding emission data and explains thederivation of emission factors by National Steeland Shipbuilding Company (NASSCO),California Air Resources Board (CARB), SARATitle Ill Toxic Release Guidance Document andthe Proposed Federal AP-42 Section 12.19 onarc welding emission factors.

4.3.1 NASSCO Developed EmissionFactorsIn 1992, National Steel and ShipbuildingCompany (NASSCO), in conjunction with Dr.Richard L. Bell of Adams, Duque, andHazeltine (AD&H), performed extensiveresearch and analysis of availableinformation on welding emissions to deriveimproved emissions factors for shipyardwelding operations. Dr. Bell was assigned toresearch hexavalent chromium and nickel.The methodology and resulting emissionfactors derived by Dr. Bell are scientifically

and statistically sound considering all of theavailable information. This sectionsummarizes reports submitted by Dr. Bell.

An extensive literature search wasperformed at the University of California atLos Angeles library, and through othersources, to develop a database ofinformation pertaining to welding technology,chemistry, emissions, and exposure. Inaddition, reports from the American WeldingSociety (AWS), the Environmental ProtectionAgency (EPA), and the San Diego APCDwere used as data sources. Due to thevarious combinations of electrodecomposition, welding processes, and variouswelding process variables, the possibility forthousands of different welding environmentsin the shipyard exists. To developgeneralized emission factors for the variouswelding processes, a statistical analysis wasperformed on the data provided by the weldemission technical reports and studiesresearched.

The research yielded that from theperspective of emissions formation, weldingprocesses can be differentiated into twobroad categories on the basis of the weldingprocess employed and how the arc isshielded from the atmosphere. The twobroad categories of welding processes arerefereed to as Gas Metal Arc Welding(GMAW) and Shielded Metal Arc Welding(SMAW). The GMAW category applies towelding processes that generally uses acontinuous uncovered wire, where the arc isshielded by a gas stream supplied by theweld gun. The GMAW process categoryincludes variations such as Flux Cored ArcWelding (FCAW) and Gas Tungsten AirWelding (GTAW). On the other hand, theSMAW category is characterized by weldingelectrodes covered by a solid flux coatingthat is vaporized in the arc to provideshielding from oxidization. The chemistry of


Chapter 4. Arc Welding Emissions Factor information

the shielding gases depends largely on the be discussed later, averages were used to fillcomposition of the flux around the rod. in the missing data and a statistical analysisAlthough the fume chemistry in SMAW and was performed to validate the averagedGMAW processes is not completely values.understood, research indicates that thedifferences between the two processmethods employed, result in metal emissionfactors that are significantly greater for theSMAW than for the GMAW process.

4.3.1.1 Emission Factor DevelopmentTable 4.1 displays the primary informationused to determine standardized emissionfactors. The goal was to develop emissionfactors that could be used throughout theshipyard for various welding rods andprocesses. It was intended that the shipyardwould only need to supply the followinginformation in order to quantify emission of acertain metal:

1) Quantity of Rod Used2)* Process Type (GMAW or SMAW)3) Composition of Welding Rod (i.e. %

chrome)

The process type determines whichemission factor to be used.

Table 4.1 presents the “master list’ ofchromium welding emission data used by Dr.Bell. The majority of the data presented inthe table is derived for the American WeldSociety (AWS). Two AWS reports wereused; Fumes and Gases in the WeldingEnvironment (1979) and an unpublisheddocument that yielded statistically consistentvalues for similar welding rods andprocesses. Other reports, referenced at theend of this chapter, authored by J. Mitti, R.MStem, E. Tompsen, and informationpresented by Tomas Weeks, San Diego AirPollution Control District were also used. Themaster data set presented in Table 4.1 hasseveral locations where data was notavailable from the respective studies. As will


Chapter 4. Arc Welding Emissions Factor lnfomation

Each data set (row) contained at least two ofthe four parameters needed. Emission datasets, without emission data, were filled usingthe average of the existing data in eachcategory. Once the data sets were filled withaverages, the fume chromium to rodchromium percentage was calculated.Assuming this value is process dependent, itcan be used for calculating the fumechromium from chromium containing weldingrods. The second important parametercalculated, was the percentage of fume-chromium that is in the hexavalent state (CrVI). These two parameters are shown asderived values in Tables 4-2 and 4-3. Theresults indicated, that the amount ofchromium in the fume from the SMAWprocess is about one-half of the GMAWprocess. At the same time, the fraction ofchromium in the hexavalent state, in theSMAW process is more than an order ofmagnitude greater than in the GMAW

process. Therefore, it validates theassumptions that the amount of chromium inthe hexavalent state is a function of weldingprocess and associated shieldingtechniques.

Some emission factors may attempt toassume that the % metal in the fume is equalthe % of the metal in the rod. Thisassumption of direct proportionality (i.e. fumecomposition = same as rod composition), isstrongly disputed by all of the data availableon weld rod emissions. For example, for rod308L-16, chrome represents 18.7% of thesolid electrode content, while chrome onlyrepresents 5.66% of the fume composition.Both chromium and nickel analysis disputethe direct proportionality assumption.Therefore, Dr. Bell determined averageproportionally and incorporated them into theemission factors as presented in Table 4.4and Table 4.5.

Table 4-4. NASSCO Derived Hexavalent Chromium Emission FactorsEmission Characteristics SMAW GMAW1) (FGR) Fume Generation Rate (lb. fume/ lb. rod) (%) 0.626% 0.413%2) Fume Composition (Fume Cr as a % of Rod Cr) 28.65% 54.64%

70.85% 6.84%3) % Cr+6/ Cr in fumeEmission Factor (EF) (* Product of above) 0.00128 0.000154

* Emission Factor has been converted to a fractionExample Emission calculation:-Assume 500 lb. usage of Rod 1500, mii-308-Welding Process = GMAW-Rod % Chrome = 20.75%

Hexavalent Chrome Emission = (AU)*(Rod % Metal)*(EF)where:(AU) = Annual Usage (Issued weld rod minus estimated waste)Rod % Metal = Individual Rod Metal Concentration (%) of rod (certifications or MSDS') (lb. metalper lb. rod)(EF) = Emission Factor GMAWCr+6 (From Table 4-4 above)

Therefore,Hex-Chrome Emission mil-308= (500 lb.)*(20.75%)*(0.000154)= Emission= 0.016 lb.


Chapter 4. Arc Welding Emissions Factor Information

Nickel Emission FactorsAs with the information for the chromiumemissions, the data for nickel wasaggregated according to welding processtypes. This database contains data fromstainless steel electrode with nickel contentin the 10 to 13 percent range and also fromhigh nickel electrodes in the 54 to 58 percentrange. Data for both nickel levels wasavailable for the SMAW and GMAWprocesses. Table 4-5 below represents theresults of the nickel emission factor

The FGR's (percent of rod converted tofume) shown in Tables 4-5 is a subset of thedata base shown in Table 4-1 and 4-2. It isnot surprising that they are virtually the sameas the fuming factors for the parentdatabase. For consistency, and because thefactors were derived from a the same largerdata set, the FGR’s used for chromium(0.626% for GMAW and 0.413% for SMAW)were used for the nickel emissionscalculations. The average ratios of fumenickel to electrode nickel of 8.97% for SMAW

Table 4-5. Derived Nickel Emission Factors

information available. NASSCO developedemission factors for Nickel and HexavalentChromium from arc welding operations(GMAW and SMAW). There are severalother metals that may be of concern (i.e.manganese and cadmium). The samemethod for emission factor development canbe applied to all metal constituents if data isavailable in the technical studies. TheNASSCO emission factors and calculationtechniques make it easily adaptable tovarious welding rods used throughout theshipbuilding process. Shipyards only need tocollect data on the weld rod composition,respetive process (GMAW or SMAW), andthe quantity of rod used (Ibs). The NASSCOderived emission factors are general enoughto be applied throughout the shipyard andare based on methods and technical data tomake them as accurate as any method ofestimating emissions from arc weldingavailable.

operations and 53.0% for GMAW operationswere to be used in calculation for all nickel-containing electrode. These are displayed inTable 4-6.

4.3.1.2 Summary of NASSCO DevelopedEmission FactorsThe NASSCO developed emission factorsare derived utilizing statistically soundmethods based on the most current technical


4.3.2 California Air Resources Board(CARB) Emission Factor EvaluationAfter NASSCO developed emissions factorswith the assistance of Dr. Bell, the CaliforniaAir Resources Board (CARB) was contactedto provide a response concerning theirsupport of NASSCOs welding emissionfactors. Richard Bode, Manager of theSpecial Pollutant, Technical Support Divisionof the CARB was asked to provideassistance evaluating the welding emissionfactors. The results of the CARB evaluationand investigation are presented in Table 4-6and 4-7.



4.3.2.1 Emission Factor DevelopmentThe CARB reviewed the scientific literaturewith the intent of refining and/or acceptingthe emissions factors developed byNASSCO. Their analysis includedinformation from two American Weld Society(AWS) reports and information presented atthe 86th Annual Meeting of the Air& WasteManagement Association (AWMA), by R.W.Gerstle, in Denver Colorado. In summary,they estimated and agreed with the fact thatthe emissions factors needed to be processdependent. They determined that separatingthe factors for SMAW and GMAW wasappropriate for emission factor simplificationpurposes.

Table 4-6 summarize the informationsupported by the CARB. They recognize andnote in Table 1 that data shows averagedpercentage of hexavalent chromium to totalchromium for the SMAW process isapproximately 63%, while it is approximately5% for the GMAW process. Their technicalevaluation supports the fact that the SMAWprocess produced significantly morehexavalent chromium than the GMAWprocess.

4.3.2.2 Summary of CARB EmissionFactorsThey recommend using the data in theprevious two tables to calculate emissionfactors, if the shipyard knows the types ofweld rod utilized and the process. Theyrecognize that the data in the tables showthat concentrations of metals in the fume arerelatively higher for electrodes With highermetal contents. Also, they believe that it isreasonable to assume that theconcentrations of the metal in the fume arerelatively higher for lower melting pointmetals. Therefore, each metal has anemission potential that is not directly relatedto the metals concentration in the weldingelectrode. The CARB also supports the factthat the hexavalent chrome factors in theunpublished AWS report were derived fromappropriate scientific analysis protocol.

They support emission factors based on theinformation provided in Table 4-6 and 4-7when the shipyard knows the type of weldingelectrode and the type of process employed.Table 4-6 displays the chromium emissionfactors developed by the CARB staff.



4.3.31990 SARA Section 313 ReportingIssue PaperIn 1990, the EPA Office of Toxic Substancespublished an issue Paper for Clarificationand Guidance for the Metal FabricationIndustry for Section 313, Toxic ReleaseInventory (TRl) Reporting. Within this IssuePaper, a section is entitled “EstimatingEmissions From Metal Welding And OxygenCutting Operations.” This paper addresseswelding emissions and how they are relatedto SARA Form R Release Reportingthresholds.

4.3.3.1 Emission Factor DevelopmentThe paper concurs that releases duringelectric arc welding operations are largelydriven by the welding rod type and thewelding process utilized. The followingequations for emission calculation andreporting are presented in this report.

Release Weight of Percent Emission Conversionof Metal = Rod Used X Composition X Factor x Factor(lbs/yr) (Ibs) (% Metal) (Ibs/ton rods) (2000 Ibs/ton)

The following eight tables are used to identifythe “Emission Factor to be used. The tablesrepresent factors for SMAW (low and highalloy), FCAW (low and high alloy), GMAW(low and high alloy), and GMAW (Copperand Aluminum wire). This data representsaverage fume generation rates and percentmetal in the time taken from the 1979document Fumes and Gasses in the WeldingEnviornment by the American Weld Society(AWS-1979). This is the same technicaldocument used by Dr. Bell to developNASSCO emission factors. The documentexplains that the tables should be used topredict the facilities toxic emissions ofManganese (Mn), Nickel (Ni), Copper (Cu)and Chromium (Cr).



4.3.4 1994 MRI Report: Development ofEmission Factors for Electric Arc WeldingThe document, “Compliance of Air PollutionEmissions Factors”,(AP42), has beenpublished by the US EnvironmentalProtection Agency (EPA) since 1972. TheEPA routinely updates this guidancedocument and provides supplements to AP-42 in response to federal, state, and local airpollution control programs. This document isthe standard federal guidance referenceused by state and local Air Quality ControlEngineers for developing emission factorsfor various emission sources.

This section of the chapter is designed toprovide a summary of the report entitled“Development of Particulate and HazardousEmission Factors for Electric Arc Welding(AP-42, Section 12.19)” developed byMIDWEST RESEARCH INSTITUTE (MRI)for the Environmental Protection Agency(EPA contract No. 68-D2-0159) final reportdate May 20, 1994. The report providesbackground information on weldingemissions to support preparation of a newAP-42 section for electric arc welding and“Draft Proposed Welding Emission Factors”.The EPA Office of Air Quality Planning andStandards Emissions Inventory Branch willuse the information presented in the report tohelp determine emission factors for weldingp r o c e s s e s .

The AP-42 report states that particulatematter and particulate-phase Hazardous AirPollutants (HAPs) are the major concern withwelding processes and associatedemissions. The report concentrates onparticulate matter emissions submicronic insize and are considered PM-10 (i.e. particlesless than or equal to 10 micrometers inaerodynamic diameter). This report onlyaddresses particulate phase air pollutants,while gas phase pollutants were not includedin the scope of the study. The report

emphasizes that only electric arc weldinggenerates potentially toxic pollutants insubstantial quantities to be of immediateconcern for EPA emissions purposes. Thelower operating temperatures of the otherwelding and cutting processes cause fewerfumes to be released. Also, due to the limitedavailability of emissions data and otherinformation for other types of welding andcutting process, only four SourceClassification Codes (SCC’s) associated withelectric arc welding were evaluated andproposed emissions factors are presented.The four processes are Shielded Metal ArcWelding (SMAW), Gas Metal Arc Welding(GMAW), Flux Core Arc Welding (FCAW),and Submerged Metal Arc (SAW).

Hazardous metals designated in the 1990Clean Air Act Amendments that have beenrecorded in welding fume includemanganese (Mn), nickel (Ni), chromium (Cr),cobalt (Co), and lead (Pb). Gas phasepollutants are also generated during weldingoperations, but little information is availableon these pollutants. Known gaseouspollutants (including “greenhouse” gases)include carbon dioxide (CO2), carbonmonoxide (CO), nitrogen oxides (NOX), andozone (O3).

MRI researched and studied over 50reference documents during the Iiteraturesearch and assessment stage. MRI outlinedcriteria with respect to the reliability of thedata provided by each report and eliminateddata that was incomplete or potentiallyinaccurate. The final set of 12 primaryreports used to determine emissions factorsis listed in Table 4-6. The AP-42 Reportoutlines in tabular form, emissionsinformation provided by each of thereferenced resource documents andprovides a summary of the sample method,number of samples and other test protocol.All of the data collection and analysis yielded


4.3.4.1 Emission Factor DevelopmentThe following section describes thedevelopment of emission factors for bothtotal particulate matter (PM) and hazardousair pollutants (HAPs) metals. Candidateemission factors were developed for SMAW, GMAW, FCAW, and SAW processes usingaverage data from each primary reference.Table 4-7 summarizes the average data

used and the candidate emission factorsobtained during this analysis for PM-10emissions. To derive each candidateemission factor, arithmetic averages of thetest data in each reference document werecalculated according to both the type ofwelding process tested and the type ofelectrode used. Next the individual averageswere grouped by process and electrode type.

Characterizing Shipyard WeIding Emissions and Associated Control OptionsPage 4-15


Weighted averages, based on the number oftests conducted in each study, were thencalculated to obtain the candidate emissionfactor for each process/electrodecombination. A rating was assigned to eachcandidate factor based on the quality of thedata used as presented in Table 4-7 andTable 4-8.

Candidate emission factors were alsodeveloped for hazardous metals listed in the1990 Clean Air Act Amendments using thedata available in each primary reference.Again, all HAP emissions are considered tobe in the PM-10 size range as discussedabove. The same averaging approach usedto develop the candidate emission factors forPM-10 emissions was used to derive similarfactors for hazardous metals. A summary ofthe data used and the candidate emissionfactors obtained is provided in Table 4-8.

4.3.4.2 Summary of AP-42 EmissionFactorsThis federal guidance document provides themost comprehensive data search of existingwelding emissions data. This report presentsemission factors for PM-10 and HAPs forspecific welding rods for four major arcwelding processes utilizing 12 primarysources of information. There is very littledata available for hexavalent chromium,however, the information provided isconsistent with emission factor informationprovided to NASSCO by the AWS.

The primary disadvantage of this report isthat it does not define how one is to predictwelding emissions from welding rods that arenot listed in the emission factor tables.Therefore, this document is only a guide tohelp provide a comprehensive summery ofavailable information concering weldingemissions. This AP42 document does notdevelop generic federally supportedemission factors that can be applieduniversally to a variety of welding electrodeand different processes.


Air Toxics Survey for Welding and Cutting Emissions

I would like to take a moment and thank you for your participation in this survey. As you are aware, theinformation that you provide will be a valuable resource for this project and I will be able to supply a moreuseful document/study for the industry as a result. I need to understand some of the constraints,limitations, and flexibility that the shipbuilding industry as a whole has regarding welding and cuttingemissions. Below you will find a paragraph outlining the objectives and benefits of the study It is veryimportant that the survey results are completed as soon as possible. If I can be of any assistance, or if youhave any questions please contact meat (619) 544-7963.

Zachary F. Jacobs P.E.Consulting Engineer

Note 1): I need to have responses to this questionnaire by June 14th 1994. Even incomplete responses willbe appreciated because I will need as much information as possible.

Note 2): Please fax information to me at (619) 232-6411 and send information to:

Zack JacobsNASSCO M/S 22A28th street & Harbor Dr., P.O. BOX 85278San Diego, CA 92186-5278

Note 3): AU shipyard specific information will be kept in my files, treated as confidential information andnot provided in the final report.

Introduction, Objectives, and Benefits of the Study:This study is sub-project to the NSRP Toxic Air Emission project and designed to provide an analysis ofcontrol technologies and options for reduction of toxic emissions from shipyard welding and hot metalcutting operations. The study will provide a comprehensive evaluation of weld and cutting fume emissioncollection and filtration alternatives applicable to the shipbuilding and repair industry. An economicfeasibility and cost analysis will be emphasized. Also, the project will investigate and identify processchanges that can be implemented to reduce overall weld fume toxic emissions. The project will reviewcurrent welding and cutting operations and available emission reduction technologies to better prepareshipyards for regulatory changes that may have an adverse impact on production operations. The study willattempt to prepare shipyards to take a proactive and information approach in the development of newenvironmental weld fume and hot metal cutting emission standards. A logicaI and well researchedapproach may influence the EPA to adopt standards more acceptable to shipyard operations. lt is plannedthat this report will provide background to assist in establishing standards that are flexible enough for theshipyard environment while minimizing toxic emissions to a degree economically feasible and operationallypracticable.

Appendix 1.

For the following four questions, please provide any information that you have on the subjects:

1) Do you think that weld fume and emissions are an important future EPA and OSHA concern for

American shipyards? Why or why Not?

2) Do you have any information on weld fume emissions and toxic emissions factors?

3) Has your shipyard been approached by the local or state air quality agencies regarding weld fume

emiss ions?

4) Have you had any OSHA compliance directives with respect to weld rod emissions?

A) Welding Operations:Please check process at your yard.

FCAW .G M A W SMAW SAW , GTAW , Brazing ,

Please list any other types of welding processes at your facility:

Do you have a record keeping system to determine how much rod wire, and electrode is used at yourfacility on an annual basis?

It has been displayed in several studies that gas shielding (GMAW) technology severely reduces that

amount of toxic weld fume generation, GMAW is also much more productive and many shipyards are

switching to wire feed GMAW. Has your facility been changing over from SMAW welding to GMAW?

If yes, which electrodes are being switched over? and on a percentage Basis, what are your

future projections for switching to GMAW? (i.e. 50/50 for rod Mil-7018M)

Appendix 1.

Is your facility making any other changes to new welding and cutting technology that may be reducing

emissions ? If yes, what?

List the major drawbacks of converting to gas shielded arc (GMAW type processes):

B) Cutting Operations:Please list all types of hot metal cutting operations at your facility and the metals being cut:

List any fume collection or controls on the cutting operations:

Total Shipyard Welding and Cutting Percentage Estimates: (Please provide best estimates for the

following welding and cutting location questions)

Total welding = 100% of weld rods in lbs.

Buildings with weld booth collection systems % (how many systems on-site? )

Buildings with/out weld booth collection systems % (how many systems on-site? )

confined spaces with ventilation %

Outdoor collection systems %

Outdoor welding no ventilation %

Others ?

Total of metals cut

Buildings with weld booth collection systems % (how many systems on-site? )

Buildings with/out weld booth collection systems: % (how many systems on-site? )

confined Spaces with Ventilation %

Outdoor collection systems %

Appendix 1.


Others ?

C) Current Shipyard Emission Collection and Controls:Do you have any internal building collection systems that clean and recirculate air contaminated with

welding fumes? If yes, please provide system characteristics (Estimates are fine) and other

information available on the system (i.e.size, CFM efficiency, disposal manufacture, cost etc.).

Building Collection Systems: (i.e.pipe shop collection system, sheet metal shop collection system, etc.)

(control types = HEPA water curtain bag house, etc.)

System 1) Exit Flow Rate CFM, # of Welding Stations , C o n t r o l T y p e

System 2) Exit Flow Rate CFM # of Welding Stations , C o n t r o l T y p e

System 3) Exit Flow Rate CFM # of Welding Stations , C o n t r o l T y p e

Confined Space Systems:

Please provide any flow rate calculation techniques and requirements for weld fume extraction in confined

spaces for shipyard applications. Are there any controls or filtration on these systems?

D) Stainless Steel and other Alloy Welding (Weld rods that contain Chromium]As you are probably aware, chromium emissions are of great concern to the EPA and OSHA Stainless

steel weld rods and wires contain high concentrations of chromium (20%). Please list any other weld rods

that contain high concentrations of chromium (i.e. aluminum welding mil-11 1)

Where is stainless steel welding performed in the Shipyard?

Buildings with weld booth collection systems: %

Buildings with/out weld booth collection system %

confined Spaces with ventilation: %

Outdoor collection systems: %


others? %

Appendix 2.

Vendor Survey:

I would like to take a moment and thank you for your participation in this survey. As youare aware, the information that you provide will be a valuable resource for this projectand the many shipyards that will read the report. The information supplied will beinvestigated and provided in a published report for the National Shipbuilding ResearchProgram (NSRP). The primary mailing of this report will be sent to over approximately350 individuals in the shipbuilding and repair industry. The shipbuilding welding issue iscentered around chrome VI emissions (0.3 -0.5 microns) from welding stainless steel.Below you will find a paragraph outlining the objectives and benefits of the study. I isvery important that the survey results are completed as soon as possible. If I can be ofany assistance, or if you have any questions please contact me at (619) 544-7963.

Zachary F. Jacobs P.E.Consulting Engineer

Note 1): I need to have responses to this questionnaire no later than Friday July 1st 1994.Even incomplete responses will be appreciated because I will need as much informationas possible to prepare a comprehensive report.

Note 2): Please send information to:Zack JacobsNASSCO M/S 22A28th street & Harbor Dr., P.O. BOX 85278San Diego, CA 92186-5278

Project Title: Weld Fume Collection and Treatment Analysis For Applicationin the Shipbuilding Environment

Introduction, Objectives, and Benefits of the Study:This study is an NSRP project designed to provide an analysis of control technologiesand options for reduction of toxic emissions from shipyard welding and hot metal cuttingoperations. The study will provide a comprehensive evaluation of weld and cutting fumeemission collection and filtration alternatives applicable to the shipbuilding and repairindustry. An economic feasibility and cost analysis will be emphasized. The projectWill review current welding and cutting operations and available emission reductiontechnologies to better prepare shipyards for regulatory changes that may have an adverse

Appendix 2.

impact on production operations. It is planned that this report will provide background toassist in establishing standards that are flexible enough for the shipyard environmentwhile minimizing toxic emissions to a degree economically feasible and operationallypracticable.

Shipyard Operations:Shipyards perform SMAW and GMAW welding in the following configurations:

a) Shops with weld stations and collection systemsFiltration End of line multistage filtration system

b) Shops without weld stations and a collection systemFiltration Individual units (roll around with minimum 8’ reach) or the installation of(a)

c) Outside areas in the shipyardFiltration Individual units, must be extremely portable and have excellent reach(10 - 15ft or long vacuum tubes (20 -30 ft.)

d) Inside compartments on-board ships or inside large blocks in the yard.Filtration: Individual units, must be extremely portable and have excellent reach(10 -15 ft) or long vacuum tubes (20 -30 ft.)

Please provide the following1) Send any information/catalogs that you feel would be helpful for this study andanalysis. (types of equipment filter information air flow rates and curves, andconfigurations)

2) Please send any information (articles, legal reports, etc.) that you may have onhexavalent chromium and/or other weld fume health problems and solutions that I shouldbe made aware.

3) I will also be analyzing steel, aluminum stainless, and other hot metal cuttingoperations in the shipyard. Please educate me on any information that you may haveabout the toxicity and/or collection problems from hot metal cutting.

4) The project will require an emphasis on cost analysis for capital expenditure andcontinued cleaning and mechanical maintenance and unit replacement. It is realized thatmaintenance are only approximate but best and worst case scenarios are to beestimated.

Appendix 2.

5) Please provide a summary of features that make your products and/or service uniqueor more efficient user friendly, more effective, or more energy efficient.

6) Please provide any information and your opinion about the advantages anddisadvantages of the different types of filter configurations (Media filters, Precipitators,automatic cleaning etc.).

7) Please fill out the following Survey Forms 1,2, and 3. Copy the forms and fill out oneform for each alternative that you feel is applicable.

Survey Form 1 requests information on roll around weld fume filtration units. Rollaround units are potentially applicable to the shipbuilding environment where onlywelding stations with chrome emissions will receive filtration.

a) The are reach should be at least 8 ft.b) A longer (20 -25 ft) tube (4” dia) attachment would be nice for some areas atshipyards.c) If you have a couple of units that I should investigate, please fill out Form 1 foreach unit.

Survey Form 2 requests information on stationary units designed to filter all weld fumesfrom shops with multiple stations. Many shipyards have collection system to ventilatethe shops. Our intention is to provide for multiple stage filtration at the exit point. Againcapital cost and continued maintenance will be emphasized.Please fill out Survey form 2 for Units designed near the following flow rates.

1) 1500-2000 CFM2) 2000-3000 CFM3) 3000-4000 CFM4) 4000-5000 CFM5) Maximum

Survey Form 2 requests information on recirculating free hanging units. Please supplyinformation on the installation and operation of these types of units. I currently have verylittle information on shipyard average room sizes and configurations. I believe that thissolution would be more practical for the colder climates with less open shops.

Appendix 3

Shipbuilding Processes, Facilities and Welding Operations:

1. Introduction to Shipyard Repair and New Construction Operations:

Il. Major Shipyard Steel Processing Facilities (Open Work Areas):

Panel Lines

Parts Fabrication and Assembly Areas and Shops

Rotary Turntables

Pin Jigs Platen Lines (Assembly)

Ill. Shipyard Production Shops (Potentially Enclosed Areas):

Pipe Shop

Sheet Metal Shop

Plate Shop

Weld School

Machining and Maintenance Shop

IV. New Construction OutFitting (Open Areas and Confined Spaces):

Unit Outfitting and Construction

On-Block Outfitting

On-board Outfitting

Appendix 3

I. Introduction to Shipyard Repair and NewConstruction Operations:

Current Steel Shipbuilding ProcessesOnce a new instruction contract is awardedand most of the detailed design andproduction planning are performed, actualconstruction can begin. To understand theshipbuilding process’, shipbuilding can bebroken up into five general manufacturinglevels. Figure 1. outlines the generalmanufacturing levels involved in theshipbuilding processes. The first levelinvolves transforming of the raw materials (i.e.steel plates, steel bars, pipes, sheet metal,electrical, etc.) into parts. Thereforepurchasing, handling, and production of theseraw materials and parts is the first level ofmanufacturing ships. The second level is thatwhich involves joining of the parts and steelmembers into subsections and sub-assemblies. The sub-assemblies of steel,pipe, venting, electrical and other outfitting arebrought together to create the third level ofship construction. The third manufacturinglevel yields what is known as the hull blocks orunits. These large blocks are transportedthroughout the shipyard and finally joinedtogether on-board the ship which is the forthlevel. The forth level of ship manufactureknown as erection. Erection is performed inone of the shipyard building positions whichinvolves assembling the blocks together toform the ship. The fifth level of shipbuildinginvolves the final installation, completion, andtesting of internal mechanisms and systemsbefore the ship can be delivered to the owner.The entire ship construction process can takeanywhere form 1 to 5 years depending on thesize and complexity of the ship.

Shipbuilding materials must first go throughseveral stages of construction before Blocks

constructed and stacked and welded togetherat shipbuilding position (i.e. ship erected). The“Assembly Line” of the shipyard generallystarts in the steel storage area. The steel isblasted With steel shot and primed with ainstruction primer which preserves the steelduring construction and allows for weldability.The steel is then fabricated into parts neededto construct the steel structure of the blockand thus the ship. Fabricated parts arebrought together to form Sub-Assemblies. Atthis stage, most of the parts are steel sectionsand plates. The Sub-Assemblies are broughttogether to form construction Blocks. TheBlocks are then outfitted with materials andparts (i.e. piping, electrical boxes, lights,ventilation, etc,). The Blocks are then liftedonto the ship, which is referred to as erectingthe ship. Once a block is Iifted onto the ship,it is welded into place and systems areinternally connected on the ship (on-boardoutfitting will be discussed in a furthersection).

The Steel Ship Repair Process:The ship repair process operates much likethe shipbuilding process although, due to thevariety of ship repair work methods can varyfrom job-to-job. Repair contracts involveengine overhauls, resurfacing the hull andsuperstructure, reconfiguration of the shipsinterior, and many other repair andmaintenance items. Ship repair contracts canlast anywhere from one day to over a yeardepending on the complexity of the job.Repair contract are generally under Severetime constraints and prompt delivery is veryimportant. Failure to deliver a repair ship ontime can result in expensive fines for theshipyard. Repair activities tend to besomewhat cyclic, therefore the work-force willexperience surges in workload.

Appendix 3

Large repair contracts and major conversionsare common in the ship repair industry. Mostof these large repair contracts are performedby shipyards that have the ability to constructships although, some strictly repair yardsperform extensive major structural repairs andconversions. Examples of major repaircontracts are as follows:

- Conversion of supply ships to hospital ships- Cutting a ship completely in half andinstalling a new section to lengthen the ship- Replacing segments of a ship that has runaground- Complete rip-out, Structural reconfigurationand outfitting of combat systems- Major remodeling of ships interior or exterior(i.e. complete overhauls of passenger cruseships)

Welding and Cutting Operations in theShipyard Environment:With the vast amount of work performed in theshipyard, welding and cutting operations areperformed at nearly every location andprocess area of the shipyard. Welding andCutting operations occur inside building,inside ships, at outdoor production lanes andin a variety of covered and uncoveredproduction areas. A large percentage ofwelding production is not continuousoperation and highly unpredictable even whenshipyard workload is steady and appearssomewhat consistent. For example, in manyareas, welding is largely driven byinconsistent work practices such as theportion of ship (engine room, machineryspaces, etc.) under construction, reworkconstruction timing, repair activities and avariety of special needs. The following threesections are designed to introduce the readerto shipbuilding and repair processes and theirassociation to welding and cutting operations

Il. Major Steel Joining And CuttingProduction Areas:There are four main areas in the shipyardwhere a good portion of the steel welding andcutting occurs. These areas are generallyopen and exposed to the ambient airenvironment although, in some shipyards,these areas may be in large covered areasand sheltered from the weather. The basicsteel structural blocks are constructed in theseareas and under high workload welding andcutting of steel, operations in these areas canbe quite predictable and consistent.

Welding operations in these areas tends to belargely SMAW, SAW, and FCAW and verylittle other welding operations are performedin these production areas. Various grades ofsteel are the major materials processed inthese areas although some Stainless Steel,Aluminum, and various piping materials canbe found in these areas from time to time.Some Shipyards have specific areas whereAluminum and Stainless Steel are welded andprocessed while other shipyards that haveless volume perform special weldingoperations at locations as space is available.Cutting in these areas tends to be with CNCPlasma Arc cutting machines and some torchcut-off used for trimming work-pieces.

Steel “Panel Lines”:Increasing needs to produce ships moreefficiently and increasing steel througput inthe late 1960’s resulted in the development ofshipyard “panel lines”. The panel linegenerally consists of motor driven conveyorswith fixed reliefs used to move large platestogether for joining (welding). Plates arejoined together with mechanical and magneticaids and seam welded. Seam welding can beperformed by either one sided or two skiedwelding. Both are usually performed withSubmerged Arc welding (SAW). Two sided

Appendix 3

welding requires the steel to be turned overfor the second side welding. Longitudinalstiffeners are also welded on the panel line,which is generally performed using gravitywelding machines (SMAW) or twin-filletmachines. A panel line could consist of thefollowing stations: Plate Storage,Alignment/tack, Machine weld (side one),turnover, Machine weld (side two), Trimexcess, Layout/tack stiffeners, Weld stiffeners,and Inspection. The assembly line operateswith the aid of cranes (bridge, overhead,etc.). Welding machines are very accessiblethroughout the panel line for productivity.

Platen Lines (Assembly Platens)Platen lines are generally the area in theshipyard where large construction blocks areassembled in the shipyard and help extendthe assembly line approach for construction ofthe steel structure of the ship. Steelsubassemblies constructed at the panel lineand plate shop are brought together at theplaten and assembled by welding and forminglarge construction blocks. The platen lines areserviced with various cranes for materialsmovement as well as welding and steel cuttingequipment in a variety of configurations. Theplaten mainly provides locations for some sub-

welding, and final weld out.

Pin Jigs for Curved Blocks:Pin Jigs are essentially platen lines used to

The pin jig is possibly one of the simplest andmost effective facilities developed by themodem shipbuilder. A pin jig is simply a seriesof vertical screw jacks that support curvedblocks during construction. The jacks can be

Curved blocks are the blocks that form theoutside of the hulls curved surface.

Mechanizing the production of curved blocks

Rotary TurntablesRotary tables are a facility that ConstructionBlocks are set into and rotate the block for avariety of production needs. The ability torotate a block at a single location reduces thenumber of crane lifts needed to rotate theblock from side to side and top to bottom.Rotary tables are used to exploit theincreased efficiencies experienced whenworker are able to weld and assemble blocksdown-hand. Down-hand welding provides ahigher quality weld With higher efficiencyrates. To a lesser extent, turntables are alsouse for outfitting materials on We blockbecause of accessibility to outfitting locations.However, most outfitting on the turntable islimited to large pipes and other steelstructures and parts that are mainly fastenedin place with bolts and steel flanges.

III. Shipyard Productions Shops:Shipyards have a variety of shops anddepartments that are involved in theshipbuilding and repair process. Most of theshops are enclosed facilities in buildings andcovered areas depending on the particularshipyard. The shops build and repair parts(piping systems, ventilation, foundations, etc.)and send them into the shipyard to beinstalled onto the ship under construction orrepair. The shops are able to producecustomized parts and pieces that are neededfor the ship. In some cases, shipyard shopsdo not construct the parts and outside sourcesare used. In either case, materials installedonto the ship are installed by a representativefrom that department (i.e. pipe is installed by apipe fitter). The following shops area sampleof the types of operations that occur in theshipyard environment. Some shipyards mayhave more shops with highly specialized

Appendix 3

functions while other shipyard may not evenpossess the shops described in this section.

Pipe Shop:The Pipe Shop is responsible for themanufacturing and assembling of pipingsystems. Manufacturing of piping systemsinvolves a variety of cutting, welding, brazing,and mechanical bending. Piping systems arethe largest outfitting task in shipbuilding.Small pipe sections known as “pipe spools”are assembled in the pipe shop and

A typical ship may have from 10,000 to25,000 individually instructed pipe spools.

The pipe shop has the widest range ofwelding and cutting operations in theshipyard. Some of the processes in the pipeshop include Pipe Welding (SMAW, GMAW,GTAW, FCAW, etc. ), Pipe Bending, FluxRemoval, Grit-blast, Pickling, Painting,Galvanizing, and Pressure Testing and pipecutting. The Pipe shop performs the majorityof their welding inside the building. Estimatesare that 75 to 90% of all pipe welding isperformed inside the shop. Therefore theremaining 10 to 25% of pipe welding occurs

discussed in the next section.

Sheet Metal ShopThe sheet metal shop is generally responsible

systems and ventilation spools. This shoputilizes engineering drawings and specialsheet metal tools to produce ventilation

work The shop cuts, shapes, bends, welds,stamps, paints, and perform a variety of othermanufacturing operations for ship ventilationsystems. Many sheet metal shops are alsoresponsible for assembling large ducting fans

and heating and air conditioning components.Sheet metal workers perform the installation ofthe ducting in various stages of construction(i.e. On-block, On-unit, On-board). similar tothe Pipe Shop, the Sheet Metal Shopperforms approximately 75 to 90% of therequired steel welding within their shop areaand the remaining 10 to 25% is transferred tothe On-Block or On-Board area.

Plate Shop:The plate shop is a generic term used for thearea or shop and process in the shipyard thatprovides steel parts cutting, bending and sub-assembly. The plate shop generally uses

produces plate shapes and parts. The shapesare cut and formed as needed with bendersand frequently welded in to sub-assemblies.The plate shop generally has ComputerNumeric Controlled (CNC) cutting machines,steel bending machines and plate bendingrolls, shearing machines, presses, holepunching equipment and furnaces for heattreatment. The Plate Shop sends the partsand subassemblies to the stages of

Plate shops tend to perform mainly SMAW,FCAW and SAW processes on variousgrades of steel. Some stainless steel andaluminum are processed through the plate

Weld School:The function of the weld school is to providetraining for shipyard welders. This is animportant function when shipyards are scalingup for a large contract or are implementingnew processes or procedures. Welders arecertified for the different types of welding inthe shipyard (i.e. SMAW tacking, FCAW,SMAW Gravity machines, GTAW, SAW, etc.)Nearly every weld process occurs in the weldschool especially when the shipyard is

Appendix 3

providing training for a large upcomingcontract.

Machine and Maintenance Shops:The machining and maintenance shopsservice the entire shipyard for their machiningand maintenance needs. The exact functionof the shipyard maintenance and machineshops are not common throughout theshipbuilding industry. Shipyard machineshops perform a variety of functions thatrange from rebuilding pumps to turning 25 footlong propeller drive shafts on lathes, while themaintenance shop performs functions fromrepairing bicycles to overhauling 200 toncranes. Equipment in the machine andmaintenance shop consist of end mills,lathes, drill presses, CNC milling machines,band saws, large presses, work tables,cleaning tanks, and other machining andmaintenance equipment. Very little productionwelding occurs in the machine shop ormaintenance shop environments.

IV. New Construction Outfitting Processesand Production Areas:Pre-erection outfitting of construction blooks isthe current shipbuilding method used by all

is the process of installing parts and varioussub assemblies (i.e. piping systems,ventilation equipment, electrical components,etc.) on the construction blooks prior to joiningthe blocks together at erection where the shipis finally assembled. The outfitting of blocksthroughout the shipyard lends itself to formingan assembly line approach to shipbuilding.

Many of the components used in outfitsystems are purchased from outside vendorsand installed by the shipbuilder. Included inthis category are main engines, generators,motors, pumps, valves, winches, cleats, andwatertight doors. A second category of outfit

components are manufactured into partswithin the shipyard shops from raw materials,such as sheet metal, piping and tubing,electric cable, joiner materials, and insulationas discussed in previous sections.

The majority of outfitting occurs within theconstruction block when the block is outside inan open or covered area (On-Block area).Similarly, a good portion of outfitting occurs insomewhat confined spaced when outfittingoccurs on-board the ship and to a lesserextent, on-block A small percentage of pipeand sheet metal welding and cutting occursduring the outfitting stages of constructionalthough a certain percentage is unavoidable.For the most part, pipe spools and sheetmetal ducting are constructed in the shopsand simply bolted into place onto theconstruction block or Unit with little welding orcutting involved. Outfitting processes dividethe shipbuilding process into stages of

can be planned to make the constructionprocess flow smoothly throughout theshipyard. For simplicity, outfitting can bedivided into three main outfitting stages of

block has been assembled. The three stagesare as follows 1) On-Unit Outfitting andConstruction, 2) On-Block Outfitting, and 3)On-Board Outfitting.

Unit Outfitting and Construction:Unit outfitting is the stage where fittings, parts,foundations, machinery, and other outfittingmaterial are assembled independent of thehull block (eg. Piping units areassembled/constructed separate from steelstructural construction blocks). Assembly ofsuch Units is call Unit outfitting and once theUnits are constructed, they are installed ontoconstruction blocks or onto the ship. Unitoutfitting is important because it allow workers

Additional copies of this report can be obtained from theNational Shipbuilding Research and Documentation Center:

http://www.nsnet.com/docctr/

Documentation CenterThe University of MichiganTransportation Research InstituteMarine Systems Division2901 Baxter RoadAnn Arbor, MI 48109-2150

Phone: 734-763-2465Fax: 734-936-1081E-mail: [email protected]