Fugitive emission certified valves enhance process plants' safety

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ISA Automation Conference 2013- EMEA (Dammam, Saudi Arabia) – December 10-12, 2013

Valve fugitive emissions

Ville KähkönenSales managerMetso Automation


Content

• General aspects of different emission standards– TA-Luft– Clean Air Act– FCI-91-1– Shell 77/312– ISO 15848-1

• Detailed view of ISO 15848-1 emission standard


GENERAL ASPECTS OF DIFFERENT EMISSION STANDARDS Brief history

TA-Luft

Clean Air Act

ISO 15848-1

FCI-91-1

Shell 77/312

Technical comparison of valve emissions standards

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Historical background of emission regulationsEmissions from valves

•Typical emissions from valve types• Regulating control valves represent ~ 70% of valve

emission

• Gate, globe valve – sensitive by design

• Plug, ball, b’fly valve – less sensitive by design

• -> Rotary valves are inherently less leaking valve type

•Typical reasons for leakage (**)• Corrosion

• Scratches

• Erosion

• Bent

(**) source: Bello, C.E & Siegell, J. H. Why Valves Leak: A search for the Cause of Fugitive Emissions. Environmental Progress. Spring 1997. Vol 16. No1 p13-15

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Historical background of emission regulationsCurrent status of industrial valve emission standards

• Nowadays we have many valve emission related test standards set by:– National legislation (CAA & TA-Luft)– Standardization organizations (ISO 15848-1 & 15848-2)– Guidelining standards (FCI-91-1, API 624 (pending) )– End users specs (Shell 77/312, ChevronTexaco)

TA-Luft (Technische Anleitung zur Reinhaltung der Luft)

Legislation• = Technical Instructions on Air Quality Control• It is Germany’s national regulation for air pollutants to protect general public and

environment• TA-Luft sets limits for different air pollutants like dust, sulfur dioxide, nitrogen oxides

& other harmful and toxic matters• Different industry areas have regulations for industry specific pollutants • TA-Luft history begins from year 1964 and latest revision has been done on 2002• Meaning of TA-Luft 2002 for industrial valves:

– Chapter 5: Requirements to Provide Precautions against Harmful Effects on the Environment

5.2.6.4 Shutoff Devices

“In order to seal shaft bushings of shutoff devices such as valves or gates,

— metal bellows with a high-grade seal and a downstream safety packing gland or

— sealing systems of similar effect shall be used.

Sealing systems shall be deemed to be of similar effect if the temperature-specific

leakage ratios can be kept during the proof procedure pursuant to VDI Guideline 2440 (November 2000 version).”

• VDI 2440 defines equivalency to bellow seals by leakage rate of flat gasket– 10e-4 mbar*l / (s*m) for temperatures <250degC– 10e-2 mbar*l / (s*m) for temperatures >=250degC– Test medium is helium, several measuring methods accepted

• Measuring conditions have been defined at ”...pressures, temperatures and spindle and shaft movements which cover operating conditions.”

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Clean Air Act (USA)Legislation

• It is USA’s national law that defines EPA's responsibilities for protecting and improving the nation's air quality and the stratospheric ozone layer. (EPA = Enviromental Protection Agency)

• CAA history begins from 1963. Latest amendment has been done on 1990.• Meaning of CAA (1990) for industrial valves

– Authorized a program to control 189 toxic pollutants, including those previously regulated by the National Emission Standards for Hazardous Air Pollutants

• CAA Title V - Permits, sets fugitive emissions to be determined acc. to EPA 40 CFR (Code for Federal Regulations) Parts 60 and 63

– The emission level is 500ppm or 100ppm (state dependent)– Measuring will be done at current useage conditions -> test medium is hydrocarbon– Measuring method shall be EPA Method 21– No endurance classes or other classification

• LDAR (Leak Detection And Repair) program is included into legislation. The purpose is to find and repair leakers by regular inspections

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FCI-91-1Informative standard

• Developed by Fluid Control Institute (FCI) to evaluate sealing properties of a stem seal design under defined conditions

• The standard has been published first time on 1991 and latest revision has been done on 2010. It is no longer ANSI standard.

• Classification has been done by:– Endurance class

– including thermal cycling (3pcs): A=100k, B=25k, E=5k– excluding thermal cycling: C=100k, D=25k

– Leakage classes– 1=100ppm– 2=500ppm

– Packing adjustment allowed only on endurance class E• Allows use of a test bench instead of a valve

– Bending loads must be simulated

• Emission measurement is done acc.to EPA Method 21– Test fluid is methane (allowing air or nitrogen at elevated temp)

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Shell MESC SPE 77/312End user specification• Shell’s standard specifies requirements for emission production testing. It is

used at oil refineries, chemical plants etc if it is specified at purchase order• MESC SPE 77/312 is a production acceptance test

– It specifies amendments to ISO 15848-2 production acceptance test– First revision has been published on 2005 and latest revision has been done on

2010.• MESC SPE 77/312 requires succesfull passing of ISO 15848-1 (amendent

by MESC 77/300 if needed)• Testing will be done for a certain percentage (2-5%) of purchase lot valves

– % is defined by leakage class– 0 pcs failed valves

• Classification has been done by leakage classes A and B for stem and bonnet leakages

– Class A (stem) limit is 1,78 * 10e-7 mbar*l/s*mm dia– Class B (stem) limit is 1,78 * 10e-6 mbar*l/s*mm dia

• Other criteria– On-off valve 5 cycles acc. to ISO 15848-2– Control valves 500 cycles (SPE 77/312 requirement)– Stem adjustment is allowed one time

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ISO 15848-1 & ISO 15848-2International Standard

• The need to clarify valve emission related issues led to the birth of ISO 15848 standard

• ISO 15848-1 and -2 have been published by International Standardization Organization at 2006

– Part 1: Type acceptance test– Part 2: Production acceptance test

• The purpose of ISO 15848-1(& -2) standard is to evaluate of industrial valves’ external packing and body joint(s) leakage

• Classification has been done by:– Leakage (A, B, C), endurance (500-2500, 20k-100k) and temperature class (-196 to 400degC)– On-off and control valves have their own endurance classes– Allows pre-defined re-tightening of the packing

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ISO 15848-1 & ISO 15848-2International Standard

• Measuring conditions include– thermal cycling– several measuring methods.

• Test fluid is either helium or methane

• Classification of the valve, for example– ISO FE BH – CC3 - SSA 1 – t(RT, 400C) – CL300 – ISO 15848-1


TECHNICAL COMPARISON OF VALVE EMISSION STANDARDS

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Technical comparisonValve emission standards

• Comparison table

ISO 15848-1 TA-Luft (VDI 2440) CAAStandard type International standard legislation legislation

Test fluid helium or methane helium hydrocarbonTesting method vacuum or flushing vacuum or flushing or pressure loss sniffing EPA21

Leakage rate 10e-6 mg/s*m or 10e-4 mg/s*m or 10-2 mg/s*m 1,76 *10e-5 mg/s*m or 1,76 *10e-3 mg/s*m 100 / 500ppmTest pressure according valve's pressure class not defined not defined

Test temperature -196C, -46C, RT, 200C or 400C not defined not definedValve cycle 100% on-off, +-10% control not defined not definedNo of cycles 500, 1500 or 2500 / 20k, 60k or 100k not defined not defined

ISO 15848-1 FCI-91-1 Shell SPE 77/312Standard type International standard Guideline standard End user spec

Test fluid helium or methane methane helium or He 10% / N2 90% mixtureTesting method vacuum or flushing sniffing EP21 sniffing ASME V app. IV or hood method EN1779 B3

Leakage rate 10e-6 mg/s*m or 10e-4 mg/s*m or 10-2 mg/s*m 100 / 500ppm 1,78 * 10e-7 mbar*l/s*mm or 1,78 * 10e-6 mbar*l/s*mmTest pressure according valve's pressure class acc.to tester, not exceeding P/T limits acc.to rating or table values for Class B valves

Test temperature -196C, -46C, RT, 200C or 400C acc.to tester, not exceeding P/T limits Room TempValve cycle 100% on-off, +-10% control 100 % 100 %No of cycles 500, 1500 or 2500 / 20k, 60k or 100k 5k, 25k, 100k 5 or 500pcs

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Technical comparisonTest gases

• Two different test mediums have been specified– Helium– Methane

• Different test mediums do not behave similar way• Factors affecting leakage values

– Molecule size, diffusion ability, viscosity– Three leakage routes: A,C =surface flows, B=diffusion

• Factors affecting packing endurance– Lubrification ability of the flow medium

• Methane based tests due working safety

is not preferred

A

B

C

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Technical comparisonLeakage units

• Different standards specify or allow different measuring methods– Global methods: vacuum or flushing, for example– Local method: sniffing– Expressed leakage value of measuring methods is different

– Global methods express in (mass) flow per time unit, for example mbar*l/s– Local methods express in concentration, for example ppmv

• Comparison of mbar*l/s vs ppmv is difficult– However, it can be done with a certain accuracy from mbar*l/s to ppmv. – It is needed to know mbar*l/s leakage and corresponding sniffing value & flow properties of

sniffing device– A conversion formula can be used to evaluate ppmv value – it is device dependent– Ppmv to mbar*l/s is not possible to convert

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Technical comparisonLeakage test methods

• It is needed to understand capabilities of different measuring methods• The most common measuring methods are:

– global methods like vacuum and flushing method– local method like sniffing

• Vacuum method– Very accurate, the reference for other methods– For example, ISO 15848 Class A allowed only to be

measured with vacuum method

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• Flushing method– Quite accurate– For ISO Class B, C, TA-Luft etc

• There are three variables which affect indicated

leakage result– Qflushing gas– Qleakage– Qdevice

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• Sniffing method– Not very accurate, however correlation exist– Factors like person, wind & device affect the result– It is very easy to use and provides quick indication

of a leaking device– CAA, FCI-91-1

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Technical comparisonThermal cycling & endurance of the test

• Thermal cycling affect packing (and bonnets) sealing ability– Packing design

– Live loaded design to compensate thermal cycling and material relaxation

– Packing material selection

• Different definition for 1 cycle (open-close) makes difficult to compare endurance of packing– ISO 15848-1: +- 10% control valves, 100% on-off valves– ISO 15848-2, Shell SPE 77/312: fully open and close

– Note: production acceptance tests

– TA-luft, CAA: not defined

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Technical comparisonLeakage limit values

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Technical comparisonLeakage limit values

• Real life leakage values for d=25mm stem size:– ISO Class A = 0,014L per year (volume of d=3cm ball)– TA-Luft <250C = 0,3L per year (a Coca Cola can)– ISO Class B = 1,4L per year (~ Large soft drink bottle)– TA-Luft =>250C = 30L per year– ISO Class C = 140L per year

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Technical comparisonValve emission standards

• Generally, ISO 15848-1 Class A can be considered the most stringest standard at the moment. – Amount of operations, including cycle and temperature cycles are defined– High temperature and long duration tests are available– The most accurate measuring method

• TA-luft <250C leakage limit is string.– Amount of operations and temperature cycles are not defined, – Measuring devices can be ”not so accurate” type

• Shell MESC SPE 77/312 Class A, ISO 15848-1 Class B is about same level

• EPA 40 CFR 60 and FCI-91-1 100ppm limits fall between ISO Class B and C


DETAILED VIEW OF ISO 15848-1 EMISSION STANDARD

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ISO FE BH – CO1- SSA 1 – t(RT, 200C) – CL300 – ISO 15848-1

Emission class

• Normal production tests are performed to the test valve– Body pressure and trim leakage testing

• A passed test will result following classification:ISO FE BH – CO1- SSA 1 – t(RT, 200C) – CL300 – ISO 15848-1• FE BH = Class B leakage performance, test gas helium

– First letter defines leakage performance: A, B or C– Second letter defines test gas: H= helium, M= methane– No intended correlation between helium or methane classes

• Leakage classes are referred:– Class A equivalent to bellows type sealing element (vacuum)– Class B equivalent to PTFE type sealing element (vacuum or flushing)– Class C equivalent to graphite type sealing element (vacuum or flushing)

• Leakage from body seals must be <= 50ppm– Sniffing method, must be separated from the packing leakage if possible


Endurance class

• CO1 = endurance class of the test• On-off valves have classes CO1, CO2 and CO3

– 500, 1500, 2500 cycles– 100% stroke

• Control valves have classes CC1, CC2 and CC3– 20k, 60k and 100k cycles– +-10% stroke at 50% opening


Stem adjustments

• SSA1 = number of stem seal adjustments• In case of exceeding the leakage limit, the stem can be adjusted • Adjustment allowed once for each qualification stage

– CO1 and CC1 allow one adjustment– CO2 and CC2 allow two adjustments– CO3 and CC3 allow three adjustments

• Number of adjustments must be reported• The number of adjustments indicates

– Packings ability to resist relaxation -> need of service in use– However, actual conditions may vary lot compared to test conditions


Temperature class

• t(RT, 200C) = covered temperature area• Temperature classes: -196C, -46C, RT, 200C and 400C

– RT covers from -29C to 40C – Appropriate P/T values must be used– Temperature and pressure must be +-5% of set point (not exceeging

+15C)– No cycling during heat up

• Two tests are needed to cover below RT temperature range– To cover range -46C to 400C requires two tests: -46C to RT and RT to

400C


Temperature class

• Temperature class is determined by location x (1) sensor

• No artificial cooling is allowed


Pressure class

• CL300 = pressure class indication• Pressure class can be expressed

– using ASME or EN PN classes– Using bars at room temp and at elevated temp (40/30)

• Finally, the certification covers– Valve types comparable to the tested valve (ball / b’fly etc)– Shaft size range 50-200%, using same design parameters– Pressures and temperatures up to classification values


ISO 15848-1 PRACTICAL ISSUES

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ISO 15848-1 practical issuesISO 15848 test requirements from manufacturer

•Heating and cooling time sets test total lenght• No artificial cooling is allowed

• One heat cycle, for a 08” valve, incl. 125 cycles, requires 160000s = 2 days

• -> CO-1 test requires more than a week, CO-3 test ~two weeks

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ISO 15848-1 practical issues

ISO 15848 test requirements from manufacturer

• ISO 15848-1, RT to 400C, CC-3 test for rotary plug valve (3” #300)

• Test duration was one month to achieve 100 000 cycles & 400C


Summary

• Many different ”standards”• Comparison is not easy

– Which standard defines what?

• ISO 15848-1 can be concidered most strict because the temperature and cycle range is definet and also the testing method

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Technology

Fugitive emission certified valves enhance process plants' safety