Oxy-Arc Underwater Cutting Recommended Practice

Oxy-arc underwater cutting recommended practice

knowledge experience

MARCH2015

REPORT

471

Disclaimer

Whilst every effort has been made to ensure the accuracy of the information contained in this publication, neither IOGP nor any of its Members past, present or future warrants its accuracy or will, regardless of its or their negligence, assume liability for any foreseeable or unforeseeable use made thereof, which liability is hereby excluded. Consequently, such use is at the recipients own risk on the basis that any use by the recipient constitutes agreement to the terms of this disclaimer. The recipient is obliged to inform any subsequent recipient of such terms.

Copyright notice

The contents of these pages are International Association of Oil & Gas Producers. Permission is given to reproduce this report in whole or in part provided (i) that the copyright of IOGP and (ii) the sources are acknowledged. All other rights are reserved. Any other use requires the prior written permission of IOGP.

These Terms and Conditions shall be governed by and construed in accordance with the laws of England and Wales. Disputes arising here from shall be exclusively subject to the jurisdiction of the courts of England and Wales.

AcknowledgementsSafety Committee

Diving Operations Subcommittee

Photography used with permission courtesy of istockphoto/think4photop and U.S. Navy (Front cover) U.S. Navy (Back cover)

Oxy-arc underwater cutting recommended practice

Revision history

VERSION DATE AMENDMENTS

2.0 March 2015 Version 2

1.0 June 2012 First release

MARCH2015

REPORT

471

Contents

1 Introduction 6

2 Mitigate risk by using alternative cutting methods 7

2.1 Saws 72.2 Shears 82.3 Arc water gouging 82.4 Kerie cable 82.5 Thermal cutting techniques that use no oxygen 82.6 Plasma arc cutting 92.7 Water jet cutting 92.8 Chain feed cutters 92.9 Orbital pipe cutters 92.10 Casing cutters 92.11 Hydraulic hand tools 10

3 Roles, responsibilities and operational control 11

3.1 The client 113.2 The diving contractor 123.3 Client on-site representatives 133.4 Dive supervisor 133.5 Divers 153.6 Dive support crew 17

4 Equipment selection 18

4.1 Welding power source 184.2 Safety switch or circuit breaker 204.3 Burning leads or burning umbilical 234.4 Ground leads 264.5 Wire (Cable) splices, connectors, and terminations 274.6 Continuity check 284.7 Oxygen 284.8 Oxygen hose 284.9 Oxygen regulators 294.10 Oxygen pressure 304.11 Torches or electrode holders 30

5 Consumables 32

5.1 Tubular steel 325.2 Exothermic 33

6 Pre-job considerations 34

7 On-site considerations and the burning operation 35

8 Proper venting 36

9 Divers PPE 38

10 Training and experience requirements 39

10.1 Training course providers 3910.2 Course contents, material and facility requirements 3910.3 Classes sizes 4010.4 Specification for instructors 40

Level 1 and Refresher Training Instructor Qualifications 41

10.5 Specification for diver and supervisor training 4210.5.1 Oxygen-arc cutting curriculum for Level 1 Beginner and Refresher Training Courses 4210.5.2 Level 1 Beginner Oxy-arc Burning Course recommendations and suggested schedule 4410.5.3 Refresher Training Course (top-up) recommendations and suggested schedule 4510.5.4 Specification for diving supervisor training 46

10.6 Maintaining competency level and experience 4710.7 Grandfathering and Recognition of Prior Experience (RPE) 4710.8 Performance proficiency criteria 48

Level 1 Beginner Oxy-arc Burner 48Level 2 Intermediate Oxy-arc Burner 49Level 3 Advanced Oxy-arc Burner 49

11 Oxy-arc cutting risks and mitigation (a commentary section) 51

Appendix A: Checklists for oxy-arc operations 52

Client Diving Representative oxy-arc cutting checklist 53Diving contractor oxy-arc checklist 54

Appendix B: Training course assessment checklist 63

Bibliography 82

6Oxy-arc underwater cutting recommended practice

Underwater oxy-arc cutting or burning is the process of cutting materials (generally ferrous metals) with a tool that combines oxygen and heat to oxidize or melt the parent material. The method has been utilized extensively in the underwater diving environment.

The frequency of diver fatalities, injuries, incidents, and asset damage occurring while using this process continues to be unacceptably high within the global diving industry.

Divers engaged in burning need to be competent in the task. Competency is achieved through training, knowledge and experience.

This recommended practice has been developed to assist with the managing this activity and to provide control measures, guidance and processes to ensure the safe execution of this technique.

No burning operation should be executed unless planned and managed in accordance with this report.

1 Introduction

Diver

Person who by qualification and experience is a competent commercial diver


A decision to use burning should always be considered against other methods. Risks should be identified, assessed and controlled.

The choice to use a diver in an oxy-arc burning scenario should be balanced with alternative methods. Many alternative cutting methods are safer and, in some cases, faster and more cost-effective than oxy-arc burning.

The use of unmanned submersibles or Remote Operated Vehicles (ROVs) with power operated saws can be considered. An ROV can also be used to assist in oxy-arc cutting by monitoring hoses, vent paths and the operation. This should be identified in the risk assessment.

Alternative cutting methods follow. Other methods of cutting exist, many using explosives, but are not reviewed in this report.

2 Mitigate risk by using alternative cutting methods

HSE (OTH 349) Evaluation, Selection, and Development of Subsea Cutting Techniques has a comprehensive list of alternatives.

2.1 SawsTubular members, pipelines and structural members can be readily cut with various types of underwater saws. Many of these saws are ROV or remotely operable.

Guillotine saws use a reciprocating hacksaw blade to make a cut. Each stroke sets the saw deeper in the cut. They can be diver or ROV deployed.

Diamond wire saws use a continuous loop of diamond-embedded wire rotating around a guide-wheel frame to make a cut. They can be diver or ROV deployed.

Hydraulic ring saws are of particular value for cutting thick cross-sections.


2.2 ShearsShears have proven to be valuable tools for remotely cutting large diameter components.

Where there is stored residual energy in the component to be cut, this method creates a risk to the diver.

Pyro-mechanical systems are, in general, shears. These devices use a small low-powered explosive charge to operate the cutter as opposed to hydraulics. They can be used to cut any shaped structural member that will fit between the shear jaws. It can be deployed by an ROV.

2.3 Arc water gougingCarbon arc gouging utilizes a copper-coated carbon electrode that melts the steel in a controllable puddle. A low pressure water jet sweeps the molten metal from the cut area.

This method is particularly suited for small cross-sections, one inch thick or less.

It does not completely eliminate the hydrogen gas build up due to electrolysis but the lack of pure oxygen in the process significantly reduces the risk.

It also provides a very controllable cut depth. Thicker cross-sections can be cut by first gouging a bevel before making the through cut.

This process also works well with non-ferrous metals.

2.4 Kerie cableKerie cable is a flexible exothermic cable suited to cutting large components. This will require a dedicated additional training course before use.

2.5 Thermal cutting techniques that use no oxygenThese are electrodes manufactured for cutting underwater that use no oxygen in the process. This method can be much slower than oxy-arc cutting and can also produce hydrogen as a by-product of electrolysis.


2.6 Plasma arc cuttingA process whereby material is removed with heat from a high energy plasma stream created in a hand-held torch and usually propelled with an inert gas.

This method can be much slower than oxy-arc cutting and can also produce hydrogen as a by-product of electrolysis.

2.7 Water jet cuttingThe cutting of metal is achieved by pumping high pressure water through a small diameter nozzle.

This process is generally not a diver-operated device and is used for inside or outside cuts made on tubular structural members where the cutting machine is set up and held in place on the member as it tracks around the member while cutting. An abrasive material is sometimes used in the high pressure water jet to aid in the cutting.

2.8 Chain feed cuttersThis machine tracks around a tubular member with the aid of a tensioned belly chain and guide wheels that encircle the tubular. The traveling cutter is hydraulically-powered and a blade cuts the pipe as the machine travels around the pipe on the chain.

2.9 Orbital pipe cuttersThese consist of a pipe clamp, guide ring and a pair of geared cutter heads. The cutters revolve around the clamp and each rotation sets the cutter deeper, automatically producing a finished cut on tubular members. These can either be hydraulic or air operated.

2.10 Casing cuttersThese are generally used for cutting pipe or casing from the inside. These cutters are deployed hydraulically and have several cutters that revolve on an axis and open outward as the cutting is done.

Tungsten carbide cutters mill away the pipe from the inside and can be used for cutting pilings on offshore structures.


2.11 Hydraulic hand toolsTools such as hydraulic grinders with cutting discs may be used effectively to cut underwater. Grinding should be considered hot work because sparks and friction can raise the metal temperature to the ignition point of any trapped flammable material.

Hand-held reciprocating saws which use a reciprocating hacksaw blade can be used to make a cut.

Hole saws are used to cut access holes for rigging underwater as well as being a good choice for cutting first vent holes in an area where burning is required.


3 Roles, responsibilities and operational control

Roles and responsibilities for diving-related projects are found at length in the IOGP Report 411, Diving Recommended Practice.

The following guidance applies specifically to burning operations in addition to the provisions of Report 411.

All personnel on a project have the right, authority, and obligation to Stop Work if they consider anything unsafe about the operation.

3.1 The client The client should provide information to assist the contractor in planning and preparing for an underwater cutting operation, including: current drawings of work site and areas specific to the burning

operation, which include pipeline drawings, platform plan and elevation drawings, P&ID drawings, detailed deck layout drawings

a detailed Scope of Work to allow the contractor to produce work-scope procedures.

The burning operation should be executed according to this report.

Any changes to the approved burning procedure should be controlled by a Management of Change (MOC) that is approved by client and contractor representatives.

Concerned parties, or approvers, should be pre-determined and documented a list generated and included in the diving project plan. Approvers may include the client, project engineer, on-site rep, contractor management, vessel master, diving superintendent and supervisors.

The clients authorized representative should participate in the contractors project risk assessments.

A Permit to Work should be in place for control of this activity.


3.2 The diving contractor The diving contractor is responsible for: the Diving Project Plan detailing the operational work-scope and how

it will progress from start to finish The HAZID and risk assessment being specific to underwater

burning (providing documentation of the trained and qualified divers identified for the operation see section 10). The dive contractor should have the dive supervisor and the divers safety delegate present in the HAZID process.

providing equipment that is suitable for the burning operation location-specific procedures for burning based on a review of all

drawings and inspection reports location-specific risk assessment/Job Safety Analysis (JSA) developed

for the planned activities of that shift. If planned activities for that shifts risk assessment change, or a shift change takes place during a burning operation, additional risk assessments should be performed.

HAZID Hazard Identification

A process of defining all potential hazards on a job by task identification and then identifying all mitigations (barriers) to prevent an incident, as well as recovery efforts defined in the event the incident does occur.

Job Safety Analysis (JSA)

Developed on-site, a group effort by the responsible crew about to perform a task to define work roles, safety considerations and mitigations prior to a task being performed.


3.3 Client on-site representatives Knowledge and understanding is essential.

Client on-site representatives should: be knowledgeable of burning operations, the primary risks, applicable

controls and the guidance in this report be familiar with the worksite location, either through drawing review

or diver inspection and assessment verify that tools are available to assess electrical current and gas

pressure/flow during the burning operation. The contractor should provide these verification tools

participate in the risk assessment process and ensure that mitigation measures are implemented during the operation.

3.4 Dive supervisor

A dive supervisor is responsible for divers overall safety and ensures that all control measures identified through the risk assessment process are implemented.

Dive supervisors should: be competent in the management of burning operations, including

knowledge of the primary risks, their controls and compliance with this report

be familiar with the work site, through procedural review, diver inspection and assessment.

maintain physical control of the dive, burning operation, and management control over the knife switch or circuit breaker controlling the electrical current to the burning torch.


It is essential that the circuit breaker/safety switch is in easy reach of the dive supervisor.

The dive supervisor should only take over or hand-over cold equipment.

participate in the risk assessment specific to the burning operation.

If a diving superintendent is present on the job, the diving superintendent should also be involved in this hand-over and ensure that control measures are being complied with.

The risk assessment process should determine whether a second diving supervisor is required on each shift. If there is only one supervisor per shift, no burning may be performed during shift handover.

It is essential that the dive supervisor does not take over or hand-over an operation to the next shift supervisor without a thorough exchange of information as entered in the operational log, equipment status, and location of diver and earthing/grounding point prior to leaving the radio or assuming control of the diver.


3.5 DiversDivers participating in burning operations should be qualified in accordance with this report.

Competency levels should be demonstrated and based on Table 1 (Diver competency levels).

Diver Competency Level

Criteria Restrictions

3 Advanced Completed 30 logged commercial dives using oxy arc as Level 2.

A minimum of 150 commercial dives. For offshore, this may be a combination of 100 offshore and 50 carried out inland.

For inland diving only, this may be a minimum of 150 commercial inland dives.

Evaluate diver competency requirements as part of risk assessment for intended operation.

No other restrictions.

2 Intermediate Completed 10 logged commercial dives using oxy arc as Level 1, plus 100 commercial dives.

Only perform cuts with no residual energy in the component to be cut.

No potential for gas entrapment.

No grout or mud behind the cut location.

No depth limitation.

Only cut component with less than 2 inches wall thickness.

1 Beginner Passed training and assessment Only perform cuts with no residual energy in the component to be cut

Water visibility not less than 2feet.

No potential for gas entrapment.

No grout or mud behind the cut location.

Only cut component with less than 1.5 inches wall thickness.

Commercial dive: A logged dive carried out after training when the diver is employed as a commercial diver

Table 1: Diver competency levels


Divers should have a comprehensive knowledge of the burning equipment being used and the scope of work.

The diver should be able to identify a problem during the process, i.e. torch malfunction, incomplete electrical circuit (poor burning), oxygen/hydrogen build up (improper venting), etc.

It is essential that the diver initially confirms the vent path using a secondary supply such as the pneumofathometer prior to commencing the cutting operation. Thereafter, the diver continually verifies the gas vent path and proves to themself and the supervisor that a clear vent path exists, is maintained, and that there is no potential for gas entrapment adjacent or above the work site.

It is essential that the diver has reviewed the HAZID, risk assessment, dive procedures and safe work plans or MOC prior to making a dive to burn.

Safe work plan

Also known as a work scope or work plan. It outlines the work required to complete a project. It is not as detailed as a work procedure, but allows procedures to be developed based on it.


3.6 Dive support crewOne experienced member of the crew should be designated by the dive supervisor for burning equipment oversight and to monitor equipment while in use.

The crew should be responsible for maintaining the burning equipment during the operation.

They should monitor equipment during use to spot trouble, with particular attention to welding leads and chaffing and to check for hot spots in the wires, i.e. lead coating producing steam, smoke, or a slick wetted appearance. Hot spots indicate possible conductor breakdown within the lead.

They report equipment status to the dive supervisor.

The crew should have a sound knowledge of AC and DC sources and principles.

It is essential that oxygen equipment is clean when handled and operated.


4 Equipment selection

Oxy-arc cutting equipment is basically welding equipment with oxygen added to the process. There are many suppliers of welding equipment globally.

See IMCA D 045, R 015, Code of Practice for the Safe Use of Electricity Under Water.

This guidance is to assist selection of equipment but it is not an endorsement or recommendation for any equipment or consumable. No endorsement is intended or implied.

Any specific equipment here is for example only.

4.1 Welding power source

The two most widely used types of welding machines used in burning are motor generators and electric inverter machines.

The motor generators are pure DC current machines run with a diesel engine, or electric motor, driving a DC generator. (Newer machines may actually be AC rectified to DC.)

The inverter machines are AC rectified to DC machines utilizing 220V or 480 V.

It is essential that the power source used to supply electrical current is installed at the dive site, vessel or structure and brought into service within the restrictions and requirements of any relevant vessel classing society, such as ABS, DNV or Lloyds.

It is essential that machine grounding issues are addressed prior to hook-up.


Before the use of any welding power source for underwater burning:

Only DC output only machines may be used. No machine that can be switched from DC to AC may be used.

No machine that has been modified in any way from manufacturers specification may be used.

It is essential that machine polarity is set to electrode negative or straight polarity (DCEN).

During machine selection, consider failure path and consequences.

It is essential that machines are designed to fail in the open circuit mode.

Isolate machines used for burning from other welding machines on the vessel (within the rules of vessel classification). On some vessels, a common ground is used for all machines that can allow stray electrical current to enter the circuit specific to the burning.

Any machine that is specifically designed for welding processes other than stick electrodes (e.g. GMAW and GTAW) may not be used unless it is DC output only.

Machines in constant use should be 400 600 A or greater, with a 100% duty cycle for the amperage setting being used.

Some machines may be rated at 60% for maximum amperage and 100% for amperages less than maximum. Machines rated at 60% duty cycle should be regularly monitored during use for overheating and pauses in the burning monitored. (A 60% duty cycle means that the machine can be used at rated capacity for 6 minutes out of 10 minutes.)

On jobs requiring day-to-day burning activity, a 100% duty cycle machine is highly recommended. These machines are much more robust and fit for maximum usage.


Exothermic electrodes require less amperage and a correspondingly lower amperage machine can be used for this type of application. If a combination of tubular steel and exothermic electrodes are planned for use, the machine should be rated for the higher amperage requirements of the tubular steel rods.

Amperage control may be remote and controlled by the supervisor from dive control.

Amps/Volts may be remotely monitored by the supervisor from dive control.

Amperage may be verified by calibrated instrumentation at or in the vicinity of the torch.

4.2 Safety switch or circuit breakerA circuit breaker such as a knife switch is the power disconnect switch in the electrical circuit going to the diver. It is used to prevent electrical shock when the diver is not actually cutting.

A manual knife switch, or single pole/single throw electrical switch, is not recommended for diving operations.

The preferred form of safety switch is a remote electrical contactor. It should be a double pole/single throw switch or two single pole/single throw switches wired in parallel that interrupts the current flow through both the torch lead and the ground lead.


OxygenOxygenOxygen

Ve

+Ve

Dive controlLeast preferable set up is with a twin pole knife switchHandle hinge position lowest

Dotted line would be the cable set up for Single Pole switch

DC Welding Machine

Ve +Ve

Dive control

Remote control of weld machine

DC breaking contactor

DC Welding Machine

OxygenOxygenOxygen

Figure 1: Basic oxy-arc cutting system

Figure 2: Preferred circuit breaker arrangement


It is essential that the switch is rated greater than the maximum amperage of the welding machine powering the burning.

It is essential that the knife switch is: mounted to a non-conducting stand not mounted in an area where oxygen could

accumulate, such as an enclosed, non-ventilated dive van

mounted in such a way that, if it fell, the knife blade would fall to the open position and not close the circuit

covered with a non-conductive housing to safeguard the operator from electrical shock for reasons as described in the warning below.

A manual knife switch produces a large arc when being connected or disconnected. This arc carries high energy and can cause electrical burn or shock. It is also a large ignition source.

Local governmental or client requirements of explosion-proof equipment may be required on offshore platforms or refinery loading docks, or chemical plant docks where ignitable concentrations of flammable gases, vapours, or liquids are present within the atmosphere during normal operating conditions.

The preferred mode of circuit interruption is through a remote circuit breaker that is housed in its own breaker box and operated through an on/off switch in the dive control.

There are breakers specifically designed for use in burning operations and feature remote switching from the operator location. This type of switch is typically permanently mounted in a safe location outside the dive control van.


It is essential that all cables providing a current path in the burning system are copper and are sized in accordance with Figure 3 (Voltage drop over distance).

It is essential that all cables, including in-line connectors that are exposed to the water or a wet environment, are fully insulated and watertight.

Wet mate-able connectors of the proper size may be used only with their locking caps secured and a strength member installed to prevent separation.

The rocking motion of a dive vessel can affect the operation of some breakers. These breakers should be selected on fitness for purpose basis and the design should be carefully evaluated. Inverter type machines are generally equipped to support remote contractor switching.

4.3 Burning leads or burning umbilical

It is essential that these breakers always fail to the open circuit.


Figure 3: Voltage drop over distance

It is essential that all leads are copper and properly sized for the application.

Generally, no wire smaller than 2/0 (9.26 mm) should be used for burning in water depths to 100 fsw (30 m).

1/0 (8.25 mm) wire is shown in Figure 3 to show amperage/voltage loss over distance as example only.

As a rule, for water depth over 200 fsw (60 m), the wire size should increase one size per 100 fsw (30 m). 4/0 (11.7 mm) and greater wire should be used for any burning in excess of 400 fsw (122 m). Doubling the wire should be considered for extreme depths over 600 fsw (183 m).


Due consideration should be taken that the burning umbilical loses efficiency and voltage when coiled and heat is generated. The leads or umbilical should be laid out across a deck to prevent the formation of an electromagnetic coil.

The circuit of the burning system starts and ends at the power source. All leads to the safety switch from the power source should be considered in the circuit length.

If large size (4/0 or 11.7 mm) wire is unavailable, an alternative means of carrying high amperage is to double the leads throughout the circuit (power and ground).

A strength member (synthetic and non-conductive rope) should be incorporated into the umbilical to reduce strain on the leads. The leads are not manufactured to hold their own weight over any length greater than ~50 ft (15.24 m).

Cable construction should be considered when procuring the leads. Cables with insufficient thickness of insulation can chaff and the insulation could become compromised.

A tougher, more durable option is double-insulated wires with PVC as the inner core cover and neoprene over the PVC. Insulation coating is critical to safe burning. Water ingress into the wire core creates resistance and electrolysis will corrode the wires severely in a short time. Welding cable utilizing paper as an insulator should be avoided due to water absorption.

An even more robust cable for burning application is Diesel Locomotive Cable (DLO). It has a 24 strand wire core versus the 30 strand wire core for welding cable. In a permanent application such as aboard a DSV this can work well between power source and safety switch. The reduced flexibility might make it difficult to deploy and retrieve from the water.


A solid and well established ground produces a more reliable circuit.

The ground should have a brass or high copper alloy clamp arrangement on the divers end to allow the ground to be securely attached to the work.

The ground lead attachment locations should be cleaned to bare metal.

The diver must avoid becoming part of the electrical circuit.

It is essential that the position of the ground in relation to the diver is such that at no time does the diver or the divers equipment become positioned between the ground and the electrode.

4.4 Ground leads

It is essential that ground wires are constructed of the same size and length as the lead wire to the torch.

Usually the ground wire is married into the lead wire and oxygen hose to form an umbilical but this is not always the case for surface supplied diving. Therefore, the ground lead might be separate from the torch lead. The end is coiled to allow the diver to place it in the immediate area of the cut.

There should be no through-water grounding.

It is essential that the ground wire is attached to the item being cut in an effort to keep stray current from the diver and other equipment such as impressed current protection systems.


4.5 Wire (Cable) splices, connectors, and terminations

Splices in the cutting leads should be kept to a minimum. A wire continuity check can determine whether a spliced lead is fit for service. Wire manufacturers might have guidance as to the maximum number of splices a wire can have and still function within intended parameters.

When splices are needed: Use wire splice kits designed for underwater

service. Never use termination lugs that are bolted

together as a means of splicing this is not their intended purpose.

Insulation provided by a waterproof moulded casting, applied within manufacturers instructions, as a splice cover is the preferred means of restoring insulation over a repair or splice.

Rubber, vinyl tape, and electrical sealant, as an insulator is not recommended as the sole means of insulation for long term use, due to chaffing and possibility of arcing through the chaffed area.

Underwater wire connectors may not be of the twisted together type. A more positive connection is recommended to reduce resistance in the connector resulting in amperage loss. Above-water connections may be a lug and bolt type, or twist lock connectors that can be disconnected. These connections must be insulated.

All termination points should be cleaned to bright copper prior to their use.


It is essential that burning leads are regularly checked, including visual examination, functional test of unit, including protective devices, plus continuity and resistance testing of cables. Check and log continuity using an appropriate insulation resistance tester to determine if the leads are fit for service.

High resistance creates heat and can damage equipment, including the power source and also creates a large voltage loss between power source and electrode.

Replace waterlogged and degraded leads. Have these checked by an electrician where an electrician is available.

4.6 Continuity check

4.7 Oxygen Oxygen used in a burning operation should be industrial quality (greater than 99%). A percentage reduction in oxygen purity will result in a reduction in cutting speed.

Oxygen pressure and flow requirements should be based on the manufacturers recommendations for the material thickness to be cut.

4.8 Oxygen hoseOxygen hoses should have a 0.375 inch (9.53 mm) inside diameter hose minimum.

For depths greater than 200 ft, a in (12.7 mm) hose inside diameter might be required.


Thermoplastic hose may not be used in oxygen service for burning.

It is essential that the oxygen hose is non-collapsible.

Routinely maintain the hose for oxygen use. O2 clean is the verifiable absence of particulate, fibre, oil, grease and other contaminants.

Restrictions through hose fittings should be minimized where possible. Full bore valves and full port regulators should be used for burning applications.

(In the cutting of non-ferrous materials, air is sometimes used as a medium to move the molten metal from the cut.)

Air from HP (high pressure) cylinders is preferred to minimize or eliminate the oil contamination that can occur with LP (low pressure) or HP air produced by a compressor.

If air is used in an oxygen hose, it is essential that the hose is cleaned prior to returning to oxygen service.

4.9 Oxygen regulators

It is essential that oxygen regulators used for burning are high pressure/high flow regulators.

Regulators should be designed to work at maximum pressure and flow against a backpressure. These regulators have larger ports within the regulator body.

A flashback arrester and pressure relief valve should be incorporated into the regulator on the downstream (low pressure) side.


4.10 Oxygen pressureOxygen pressure requirements should be verified by the diving supervisor on the job site.

Using pressures greater than what is required will increase the probability of an explosion by introducing more oxygen than is needed or producing a build-up behind the cut.

The high volume, high pressure, two-stage regulator should be capable of delivering 70 CFM.

Oxygen pressure should be reduced to 40 bars or less at source

The pressure and volume of oxygen is critical to efficient cutting. To calculate the required gauge pressure at any depth, always use the manufacturers recommendations.

4.11 Torches or electrode holdersTorch heads require regular maintenance and should be marked with an identification number.

Maintenance should be logged in the Equipment Maintenance System (EMS) to track the life of a torch and burning umbilical.

A new torch should be inspected following the manufacturers recommendation prior to use.


Inspect torches and after each burning operation. Check all threaded pieces for contamination or

slag in the threads. Clean accordingly. Check electrode collet for electrolysis erosion

or arc damage. Replace as required for tight electrode fit.

Inspect all rubber washers and O-rings for damage.

Inspect flash arrestor for serviceability. The oxygen delivery system (field check) A

flash arrestor has to be installed in the torch. Prior to use, inspect the torch, and assemble

it in accordance with the manufacturers specification.

Follow the manufacturers specification for pressure testing the torch and system.

Inspect the welding cable or torch lead at the connection to the torch body. Electrolysis will result in this connection becoming loose over time. Re-tension it according to manufacturers specification.

Warning: Electrolysis can produce hydrogen as a by-product of the process. This hydrogen can build up in the torch head voids if dead space exists. Check for work hardened areas in

the welding cable adjacent to the torch handle. Work hardened cable might indicate the presence of broken conductor strands inside the insulation.

Torch manufacturers should provide a schematic breakdown and recommended maintenance program to the consumer.


5 Consumables

In oxy-arc cutting there are two basic electrode (rod) designs: tubular steel electrode and exothermic rod.

Each rod type has its inherent strong points and weaknesses. Both types are commonly used and the equipment is the same for each type of rod, with the exception of higher amperage machine requirements for tubular steel electrodes. It is not uncommon to see both types of rod on a job and being used for the same work.

For large burning projects, the electrodes should be qualified by testing to establish the best fit for purpose.

A brief definition of each rod follows. Exact amperage requirements should be established by testing. Examples given only suggest ranges for use.

5.1 Tubular steel Tubular steel rods are composed of a hollow, solid steel tube that is coated with a flux or waterproof coating. Some designs are covered with a waterproof coating over the flux.

The typical rod is a 5/16 in (7.9 mm) diameter tube with a concentric through hole that is approximately 1/8 in (3.17 mm) in diameter. Tubular steel rods can only be used for cutting when the electrical circuit is energized (hot). Tubular steel rods require more amperage (~300 A) to perform efficient cutting and work very well on clean steel of any shape or design.

Keep burning rods in a dry storage area. Do not let them become exposed to extreme climatic conditions or contaminates that can have a reaction with oxygen.

Dispose of: rusted rods rods that have been in the water and returned

to the surface unused they are unfit for service.

Never oil rods to reduce corrosion effects. Oil and oxygen can produce an explosion.


Because of the need for electrical continuity, the tubular steel rods cannot burn through heavy corrosion or marine growth efficiently. However they can be more accurate and, because constant electrical contact is required, when burning close to another member that must not be damaged, rubber matting or insulation can guard against arc strike.

Typical rod travel during a cut is usually more than that of an exothermic rod. Generally, tubular steel rods work better than exothermic rods on steel thicknesses in excess of one inch (25.4 mm), making a cleaner cut with less chance of an unburned section (hanger) being left behind.

Tubular steel rods produce a higher arc temperature than exothermic rods. Arc temperature can be as high as 20,000F, depending on amperage.

5.2 Exothermic Exothermic rods are comprised of an insulated thin sheet steel outer cover over several small diameter alloy wires used as fuel wire. The small diameter wires are alloyed with materials that exhibit exothermic properties.

The rod is typically 3/8 in (9.5 mm) in diameter and the inner wires are arranged to form a hollow centre as an oxygen path. These rods require much less amperage or no electrical current at all after ignition.

Once the rod is ignited, the electrical current can be shut off. The heat is maintained by thermo-chemical reaction sustained by the exothermic materials. Some burning might require a low amperage (~150 A) boost, especially in thicker materials. Once the oxygen is shut off, the reaction stops.

Oxygen must be shut off from the rod to stop the burning process once started.


6 Pre-job considerations

Risk-assess all burning operations.

This will follow the contractors process and be in addition to the support requirements for this process.

Only use divers and supervisors that follow the training and competence guidance of this report.


7 On-site considerations and the burning operation

The metal in the cut area should be thoroughly cleaned before burning begins. Metal should be cleaned of all corrosion scale, calcareous growth (barnacle bases) and paint or coating. Cleaning should be done on both sides of a cut when practical.

Proper cleaning prior to cutting will reduce the amount of oxygen consumed while making a cut.

If the areas of material require cutting are in places where effective cleaning cannot be achieved, the selection of electrode/rod types should be considered. Using an exothermic rod that does not require constant electrical contact could be the preferred choice in this case.

An accurate assessment of the burning requirements is always required. This should include inspection dives or ROV to trace out gas paths, possible impact to adjacent structures or piping. The material to be cut should also be known.

Any material other than carbon steel might not be easily cut with the oxy-arc process. Non-ferrous metals are cut by melting not oxidation and unsuited to the oxy-arc process.

Paint or other petroleum-based coatings can produce a flammable gas when not completely burned. This can create an explosive environment if mixed with oxygen.

Never cut materials such as aluminium, magnesium, or zinc with the oxy-arc process.

These materials are very dangerous to the diver doing the burning.

These metals will actually burn on their own in the presence of high temperature and oxygen.

Cut these materials using alternative means.


8 Proper venting

It is essential that a suitable gas path for the elimination of volatile gases from adjacent to and above the cut is achieved prior to commencing the oxy-arc cutting operation.

The diver and supervisor must ensure that this gas is being removed from the area and not building up in pockets. This gas path confirmation can be accomplished in several ways:

Vent holes can be drilled, or cut, above the intended cut line. If the content of the void behind a cut is not known, drill or saw cut the holes into the material. Vent holes made by drilling should be made with a drill using a reduced RPM to prevent the cutting edge of the drill bit from creating enough heat to ignite a combustible gas

Circular saws and grinders with cutting blades can produce sparks and heat which have been known to ignite combustible gas.

Always assume hydrocarbon presence until proven otherwise.

Once penetrative holes are drilled, windows should be enlarged to allow adequate flow to vent properly.

Prove the vent path by flowing secondary gas, such as from pneumofathometer.

Consider and verify what is behind the cut before any vent holes are made.

Stored energy can shift the material being cut.

Remove mud, grout, or other material built up behind a proposed cut. If it is not possible to remove the background mud, use alternative cutting methods.

Oxygen or other combustible gases can naturally rise away from the cut area and be of no consequence. Verify this. Consider internal structural braces within a structural member such as a tubular diagonal brace with internal stiffener rings as a possible gas entrapment. If gas introduced into the member does not vent in a predictable amount of time, consider it as blocked and make alternative venting schemes considered.

When burning on an incline or vertical position, do it from the top moving down to reduce or eliminate the possibility of burning into a gas pocket. Make more than one vent when burning in the horizontal directions

Cutting into a tubular, tank or enclosed space vent holes will be needed

Do not perform burning on a pipeline, vessel, storage tank, or anything having previously contained a hydrocarbon product. Residual hydrocarbons in any amount can become quite explosive when mixed with oxygen.


Other hazards to consider when establishing a vent hole are:

differential pressure residual forces in material causing load shifting internal structural bracing within a closed member, such as an internal ring

stiffener in a tubular member marine growth that can trap gases external coatings.

The process to verify flow path and identify any potential pockets should be in three phases:

1. Identification2. Mitigation 3. Verification, which includes continuous monitoring as the cut progresses or

locations changed.

Identify flow paths and investigate potential gas pockets using drawings, inspection dives performed, and any other information available to project planning team. Compose this team of personnel that have experience and competence in the type of burning to be accomplished and knowledge of the structure being burned.

Mitigate the risk by establishing vent holes or windows to allow escape of explosive gases, removing potential barriers to gas flow behind the cut and be aware of trapped gases above vent windows that may ignite.

Warning:

Hot slag encased in an oxygen bubble can travel up several atmospheres in the water column past the venting window and ignite gases or hydrocarbons trapped above the vent location.

If burning operations are being conducted around a live structure, a water curtain (deluge) should be used around the area that the gases are surfacing to break up any bubbles that may have burning slag within the gas bubble.

Verify venting to prove it is adequate. One recognized method is to introduce a burst of air/inert gas into drilled hole at potential cut location and record the time elapsed until it exits the vent window.

Monitor and verify venting when conditions, location, divers and supervisors are changed.


9 Divers PPE

The following PPE should be worn by the diver for the burning operation in addition to standard PPE required for all diving:

non-conductive gloves. The divers gloves should not become saturated with or entrap gas

eye protection for arc flash in clear water with #4 shaded lens or darker. protective clothing to protect the diver and dive suit from damage or

burns from hot slag.

Personal jewellery may not be worn during burning. Gold is a highly conductive material and can increase the chances of the diver becoming a part of the electrical circuit.


10 Training and experience requirements

10.1 Training course providersThe training provider should be an accredited commercial diver training school, professional training establishment, or in-house training conducted by a dive contractor.

All training providers should plan and deliver courses following this guidance as a minimum, but may elect to provide additional training to accommodate advanced training, project specific training or national standard training.

All training providers, regardless of affiliations or accreditations, should conduct training and maintain the training facilities according to local and/or national Health and Safety laws.

Where diving and diving related activities are a part of the training course, that activity should be performed in accordance with IOGP Report 411, Diving Recommended Practice.

10.2 Course contents, material and facility requirements The course should be structured to establish Terminal Learning Objectives and to establish a pass and fail criteria for the students performance.

Courses should be performed in a properly outfitted training facility that is appropriate for the task. See Appendix B, IOGP oxy-arc cutting training course assessment checklist.

Courses should be supported with training aids and learning material which should include a lesson plan, course booklets, video and power point presentations, diving equipment and cutting equipment that is identified in this report.

Equipment set-up and dry burning instructions should be performed at a properly outfitted hot-work location where safe and practical performance of the task can be conducted.

Wet training may be performed in either a tank or open water location that is appropriate for an entry level diver. It is essential that conditions allow for safe and practical task performance and monitoring with closed circuit video or other means, such as windows, that allows for close visual witnessing of progress. More than one camera or window may be required to obtain this level of inspection.

During wet training modules, there should be maximum of two divers in the water for each diving supervisor/instructor at the dive site.


10.3 Classes sizesThere are several considerations for class size: instructorstudent ratio number of training aids available for students time management for a 40 hour course of instruction practical training module time available for each student wet training time availability for each student diver. (Each diver will

require up to several hours in the water.)

It is envisioned that class size would be no larger than 15 divers.

Training module Number of students Number of instructors

Class room lecture 15 1

Practical modules (Dry) 5 1

Wet training modules 5 (2 diving at a time) 1

Table 2: Suggested instructorstudent ratio per module of training

10.4 Specification for instructorsThe instructor or instructing staff (more than one instructor) should be qualified to plan and deliver the course within the scope of this recommended practice. There is no limit to the number of instructors that a provider may use.

The training course should have at least one instructor that is qualified to plan and deliver the training course and to assess the trainees level of competence. Qualified Competency Level 2 or 3 divers may assist the instructor to help provide extra experience and skill where necessary. See Table 1 (Diver competency levels).


Level 1 and Refresher Training Instructor QualificationsInstructors should have: prior formal training in the theory and techniques of oxy-arc cutting.

Formal training may include accredited diver training courses or military training that included oxy-arc cutting as part of the training

documented experience of oxy-arc cutting as an offshore or inland diver, on at least 40 oxy-arc cutting dives

experience using exothermic and tubular steel rods. Experience for use of both rod types may also be gained by practicing in the course wet trainer

at least five years of experience as a diver and performed at least 250 dives

comprehensive knowledge and understanding of the topics and information contained in this report and IOGP Report 411

the necessary qualification and/or skills to perform workplace technical training and assessment according to the training providers accreditation requirements. Where there is no accreditation requirement for workplace training, the instructor should at least attend a vocational education trainers course (Train the Trainer) or Workplace Competence Assessor course

the ability to demonstrate in-water tasks.

An example of an accredited/qualified trainer is the Australian TAE40110 Certificate IV in Training & Assessment.

See IMCA C 007 Rev 1, Guidance on Assessor Training and IMCA C 016, Guidance on Verifier Training for further information.


10.5 Specification for diver and supervisor training

10.5.1 Oxygen-arc cutting curriculum for Level 1 Beginner and Refresher Training Courses

Training and assessment in the hazards and controls of conducting oxy-arc cutting should contain the following topics and learning points.

The relevant parts of this report should be used as the basis for training these points.

Risk assessment and MOC: hazards mitigation controls.

Principles of operation: alternative cutting theory of oxy-arc burning types of material: ferrous and non-ferrous oxygen systems circuit breakers safe consumables and their correct application venting grounding gas migration residual energy differential pressure hydrocarbons slag cutting on different structures (tubular, wire, solid, porous) confined space burning dredging and below mud line burning advantages of surface cleaning cutting in contaminated water tides, currents, splash zone electrical risks and considerations water depth effect on burning visibility effect on burning diver positioning during burning bell position, relative to burning operation burning and Simultaneous Operations (SimOps)


lift bag use while burning lifting while burning rigging techniques to aid burning.

Underwater cutting rods: tubular steel electrodes exothermic rods general cutting rod amperage requirements tubular steel electrode amperage exothermic rod amperage other rod options.

Oxygen requirements: oxygen delivery pressure oxygen purity oxygen safety burning oxygen segregation from main gas stores.

Cutting technique: tubular steel electrode exothermic rod other rod options.

Troubleshooting: malfunction symptoms probable causes identification and problem solving.

Post-dive maintenance: electrode storage torch maintenance.


10.5.2 Level 1 Beginner Oxy-arc Burning Course recommendations and suggested schedule

Level 1 is considered basic training and entry level. Students should be given the opportunity to use exothermic and tubular steel.

The Level 1 Oxy-arc Burning Course should be set up to provide each diver with a minimum of 40 hours of training and assessment.

Training module Hours Criteria

Classroom Instruction and Assessment

8 Lecture and instruction to the suggested curriculum topics to be completed over the course

Practical equipment set-up

3 Equipment set-up may be performed during the dry burning or wet training phase

Dry burning (Cutting in dry conditions)

5 Dry burning may be substituted with wet training where conditions applya

Diver should practice with each rod type

Wet training modules

24 Each student must burn at least 50 rods of each type.

Each diver must complete the Level 1 Performance Proficiency Criteria. See 10.8 (Performance proficiency criteria)

The 100 rod minimum may be included as part of the proficiency test

a In some regions where laws governing air pollution are in effect, dry burning can be substituted for more in water burning. Dry burning is a valuable method for understanding the concept of oxy arc burning and should be incorporated in the training where possible and should not be deleted unless required by outside governance.

Table 3: Level 1 Beginner Oxy-arc Burning Course recommendations and suggested schedule


10.5.3 Refresher Training Course (top-up) recommendations and suggested schedule

Refresher training should consist of an 8 hours of review and practice.



3 Refresh in oxy-arc cutting hazards and mitigations and review of IOGP Report471

Wet training modules

5 Wet training and cutting practice to the appropriate level of proficiency that the student is requalifying for

Table 4: Refresher Training Course (top-up) recommendations and suggested schedule


10.5.4 Specification for diving supervisor training Dive Supervisors that do not have a diver burning qualification or have not completed a Level 1 Oxy arc Burning course should follow this recommended curriculum.



8 Lecture and instruction in the suggested curriculum topics listed in 10.5.1 (Oxygen-arc cutting curriculum for Level 1 Beginner and Refresher Training Courses)

(Maybe the same module as Diver Level 1 Oxy-arc Burning Course)

Practical equipment set-up

3 Equipment set-up may be performed during the dry-burning or wet training phase.

Observation of wet training modules

5 Student supervisors should have practical training in the role and duties of the oxy-arc burning supervisor. This training should take place, under supervision of the instructor and may take place during a diver wet training module.

Table 5: Oxy-arc Burning Training for Dive Supervisors should consist of 16 hours of training in theory and practical assessment


10.6 Maintaining competency level and experienceValidity for each competency level should be maintained by performing five hours of documented burning experience each year. Contractor or client may recommend Refresher Training (Top-Up) if the diver has no documented burning practice in the previous 12 months.

In addition to the normal dive profile information, divers and supervisors should maintain the following information about each oxy-arc burning dive in their personal logbooks and competency booklets.

Entries should be validated by the Contractor and Client Representative: description of object(s) being burned type of material and thickness type of electrode and burning equipment being used description of circumstances or environment where the cutting took place common and uncommon hazards and mitigations relevant to the

burning task.

10.7 Grandfathering and Recognition of Prior Experience (RPE)

Divers with prior training and experience in oxy-arc cutting may be assessed and tested to qualify for a specific competency level.

An assessment of the candidates dive logs and experience should be performed by the contractor and training provider. The assessment should show evidence of experience equal to one of the diver competency levels in Table 1 (Diver competency levels).

The candidate should then attend a Refresher Training Course and complete the equivalent performance proficiency test criteria. See Figure4 (Training and experience scheme flow chart).


10.8 Performance proficiency criteriaThis performance proficiency recommendation has been incorporated to provide additional criteria for the training and experience requirements in this report.

The intent of this section is to allow for: divers that have lapsed in competency level due to lack of recent

burning experience in previous 12 months grandfathering and recognition of prior experience client companies to establish a burning qualification for project

specific requirements.

The proficiency criteria levels in this section may supplement the diver competency levels in Table 1 (Diver competency levels).

The recommended time criteria in Level 2 and Level 3 are suggestive and are meant to place qualification criteria on the divers capability and efficiency. The client operator may elect not to impose a minimum time criteria. Training providers should endorse the students course completion certificate with the electrode types and proficiency criteria achieved.

Level 1 Beginner Oxy-arc BurnerThis is the starting level of proficiency. Candidates will be required to satisfactorily demonstrate safe and successful burning technique as follows.

Exothermic Rod Burn 6 inch dia. Schedule 80 pipe using no more than 4 rods.

No Hangers. Burn 1 inch thick clean steel for a distance of 18 inches using no more

than 6 rods. No Hangers. Burn 2 inch thick clean steel for a distance of 18 inches using no more

than 10 rods. No Hangers.

Tubular Steel Electrode Burn inch thick clean steel for a distance of 18 inches using no

more than 4 rods. No Hangers. Burn 1 inch thick clean steel for a distance of 18 inches using no more

than 6 rods. No Hangers. Burn 2 inch thick clean steel for a distance of 18 inches using no more

than 10 rods. No Hangers.


Level 2 Intermediate Oxy-arc BurnerCandidates will be required to satisfactorily demonstrate safe and successful burning technique as follows.

Level 2 allows a diver to qualify on either type of electrode. This is the only level where a burner may qualify for either rod type, instead of both rod types.

Exothermic rod Burn 6 inch dia. Schedule 80 pipe using no more than 3 rods. No

Hangers. 5 minute start to finish. Burn 1 inch thick clean steel for a distance of 18 inches using no more

than 5 rods. No Hangers. 15 minute start to finish. Burn 2 inch thick clean steel for a distance of 18 inches using no more

than 9 rods. No Hangers. 18 minutes start to finish.

Tubular steel electrode Burn inch thick clean steel for a distance of 18 inches using no

more than 3 rods. No Hangers. 5 minutes start to finish. Burn 1 inch thick clean steel for a distance of 18 inches using no more

than 5 rods. No Hangers. 8 minutes start to finish. Burn 2 inch thick clean steel for a distance of 18 inches using no more


Level 3 Advanced Oxy-arc BurnerThis is the highest level of proficiency and candidates will be required to satisfactorily demonstrate safe and successful burning technique as follows:

Exothermic rod Burn 6 inch dia. Schedule 80 pipe using no more than 3 rods. No

Hangers. 4 minute start to finish. Burn 1 inch thick clean steel for a distance of 18 inches using no more

than 5 rods. No Hangers. 12 minute start to finish. Burn 2 inch thick clean steel for a distance of 18 inches using no more


Tubular steel electrode Burn inch thick clean steel for a distance of 18 inches using no

more than 3 rods. No Hangers. 4 minutes start to finish. Burn 1 inch thick clean steel for a distance of 18 inches using no more

than 5 rods. No Hangers. 6 minutes start to finish. Burn 2 inch thick clean steel for a distance of 18 inches using no more



To qualify for Refresher training diver should have completed prior Oxy-Arc Cutting 40 Hour

Training Course

Complete an Oxy-Arc Cutting Refresher Training Course

Complete an Oxy-Arc Cutting Refresher Training Course

Complete the Oxy-Arc Cutting 40 Hour Training

Course

Complete Competency Level 2 Intermediate criteria

Complete Competency Level 3 Advanced criteria

Complete the Performance Proficiency Test equivalent to the competency level

requalifying for (1,2 or 3) after refresher training

Contractor/Training prov. perform diver experience assessment compared to Diver Competency Level

1, 2 or 3 (Sec 5.5)

Complete the Performance Proficiency

Test to the equivalent level of assessment (1,2 or 3) that

was conducted

Maintain 5-hrs burning

practice in previous 12-months?

Qualified Competency Level 1 Diver Burner



Yes

No

Normal scheme Refresher schemeGrandfather and RPE scheme

The timings are used when testing/training candidates to evaluate performance they have no bearing on operations.

Figure 4: Training and experience scheme flow chart


11 Oxy-arc cutting risks and mitigation (a commentary section)

The following commentary represents best industry practice and safety warnings in regard to using the oxy-arc underwater cutting process.

Many of these comments are included in the reference documents and are important enough to be mentioned here.

Underwater burning produces a combination of pure oxygen and hydrogen gases as a by product of electrolysis and heat generated over 2000F/1093C). When trapped in a confined or unvented area, this gas mixture will produce a serious explosion when ignited.

Holes in the outer insulation cover of a burning lead can bleed a red copper oxide from the electrolysis in the wire core if the lead has been submerged in water.

Never burn where there is a pressure differential from one side of the cut to the other. A differential that causes either a pressure release or a vacuum is an extreme danger to a diver.

The diver must ensure there are no hydrocarbons present that can ignite during the burning process.

Never burn into an area that is not vented.

In order to flush out any hydrogen gas pockets in the equipment, oxygen must be flowed through the torch and rod prior to energizing the circuit.

Always follow manufacturers instructions when using oxy-arc cutting equipment.


Appendix A Checklists for oxy-arc operations

Two checklists have been added for use and to give a quick reference as to what is required both pre-operation and pre-dive.

The (pre-operation) Client Diving Representative oxy-arc cutting checklist will provide a quick reference of compliance for project managers of both the client organization and the contractors organization and is primarily to assist the IOGP Diving Client Representative(s).

The (pre-dive) Diving contractor oxy-arc checklist has been created as a reference to assist the diving contractor in managing the operation.

53Appendix A - Checklists

Client Diving Representative oxy-arc cutting checklist

No. Criteria Yes/No Comments

1 Has a risk assessment been carried out to establish whether alternative methods of cold cutting are more appropriate?

2 Have site-specific procedures for oxy-arc cutting been created for the task?Including material composition, thickness, configuration, surface condition, internal pressure, hydrocarbon content, Identified cutting lines and venting positions, measurement/proving of venting and PTW & isolations?

3 Are there sufficient competent divers and supervisors trained to meet the requirements of this RP?

4 Has a site-specific risk assessment been carried out on the work procedures with client personnel, diving contractor personnel, including supervisors and divers?

5 Have all necessary isolations been identified and the PTW issued

6 PTW Number added to this list PTW No.

7 Have the cut areas been confirmed with the Procedures? Have vent whole locations and cut lines been marked on the material?

8 Is the burning equipment set-up, tested and maintenance compliant with this RP?

9 Can the diver and supervisor confirm there are no areas for gas entrapment in the cutting vicinity?

10 Confirm that the bell set up position and trunking have been located to avoid any potential for bell atmosphere contamination?

11 Has the material to be cut been cleaned of coatings and marine growth?

12 Confirm that the diver is to cut vent holes on instruction from the supervisor using the methods at the locations stated in procedure.

13 Ensure that the supervisor and diver have confirmed all vent paths are functioning and monitored.

14 Confirm that the diver is now ready to undertake oxy-arc cutting operations safely.


Diving contractor oxy-arc checklist

Equipment Yes No

Oxygen Cylinders

Marked according to IMCA

Oxygen warning signs in place

Oxygen purity certificate from the gas supplier.

Oxygen cylinders marked for Industrial Gas Do not connect to BIBs lines Do not connect to metabolic make up gas lines.

Cylinder Pressure test certificate in-date

Quad framework in good condition look for pits painted over and/or filler.

Check under the frame for corrosion that could affect structural integrity.

Check Cylinders for corrosion on the base (contact area with quad frame).

Quad Lifting Pad Eyes pull test and MPI in-date

Quad Slings & Shackles fit for purpose & in-date load test certificates

Cylinder security

Cylinder paint and corrosion

Cylinder neck valves blanked and capped

Cylinder neck valves in good condition

Cylinders and neck valves grease-free

Dropped object protection in place

Burning oxygen segregated from DDC gas Fire concern Non-medical gasses connection to gas for

human consumption concern

Quads sea fastened securely

Fire detection in place

Fire suppression in place

Fire hose nearby

Burning Oxygen is not stored below deck

Quad Electrically grounded to hull of vessel.

Quantity Sufficient for the job

Quantity Burning gas is not included in Treatment mix or Metabolic check/confirm on LSS gas board.

Quantity Quad can easily be changed out.


Equipment Yes No

Oxygen Manifold (on the Quad)

Fit for purpose

Integral with the quad

Fabricated from suitable materials rated for oxygen (see Swagelok catalogue or similar).

Should not be carbon steel, copper, or iron tube. Should not contain galvanized or cadmium coated fittings.

Pressure test certificate

Oxygen cleaned to an internationally recognised standard and certified by a competent person.

Valves must be rising stem type.

Valves Fit for purpose i.e. rated for oxygen use by the manufacturer

Valves oxygen clean

Visual check metallic pig tails for: crush, crimp, twist, buckle, cracked joints, in-appropriate fittings, excessively tight radius.

If the pig tails are silver soldered to a main tube request a pressure test certificate.

(Hydro test of pipe work is usually 1.5 WP) (200 bar WP requires a TP of 350 bar)

Visual check flexible hose pig tails for: crush, crimp, twist, buckle, inappropriate fittings, and excessively tight radius.

If the pig tails are flexible request a pressure test certificate.

(Hydro test of pipe work is usually 1.5 WP) (200 bar WP requires a TP of 350 bar)

Purpose-built oxygen distribution manifold should be: Designed to a recognized international standard Constructed from materials designed for oxygen use Capable of withstanding up stream pressure or a relief valve should

be fitted to protect LP components Certified by a competent person Oxygen cleaned and certified Pressure tested to and internationally recognized standards

Regulator Fit for purpose (High pressure & High flow )

Oxygen-cleaned

HP & LP gauges fitted and operational (scale appropriated)

HP filter in place

Protected from dropped objects

Bull nose is the correct type for the cylinder

Pressure relief valve to protect downstream components.


Equipment Yes No

Burn back(automatic device designed to sever the connection between the hose/regulator in the event of internal hose fire).

Relief valve fitted (downstream component protection)

Generally set at 90 psi over bottom, pressure reduced to 40 bar or less at source

Oxygen Hose: From Quad regulator to the Top-Side Burning Umbilical connection

must not be wire-reinforced. Hoses constructed from non-conductive materials.

Hoses & Tube runs

Oxygen hose is fit for purpose and designated for oxygen transport by the manufacture.

Hydraulic Hose: From Hydraulic Power Pack to the Burning Umbilical Reel

connection must not be wire-reinforced. Hoses constructed from non-conductive materials.

Burning Umbilical: Oxygen hose fit for purpose and designated for oxygen transport by the manufacture.

Oxygen hoses pressure tested and certified by a competent person.

Oxygen cleaned to an internationally recognized standard and certified by a competent person.

Whip checks used where required.

Oxygen carrying hose/tube specifically related to thermal cutting operations not bundled with life support gas, electrical, communications or other services critical to the diver, bell or DDCs life support functions

Oxygen carrying hose/tube does not pass through machinery spaces or other areas that contain flammable substances or may promote or enhance combustion. (Such as hydraulic power pack rooms etc.)

Oxygen carrying hose/tube does not pass through machinery spaces or other areas that contain flammable substances or may promote or enhance combustion. (Such as hydraulic power pack rooms etc.)

Designated SWL must be marked on the frame

Umbilical winch Securely sea-fastened

Load tested and deck tie down joint ND inspected

Primary Brake should be automatic when the lever returns to neutral

Secondary brake may be manual

Maximum heave force to be entered in the risk assessment

Oxygen hose connection should be on the opposite side from the hydraulic connections.


Equipment Yes No

Oxygen hose to have a double block and bleed facility

Valves should be rising stem type.

Valves Fit for purpose, i.e. rated for oxygen use by the manufacturer

Valves oxygen clean

Electrical connections must be designed for the application intended and fit for purpose.

Umbilical winch Lifting Pad Eyes in pull test and MPI date

Umbilical winch Slings & Shackles fit for purpose and in date.

Must be electrically grounded to the vessel with heavy duty cable.

AC welding current output machines are unacceptable.

Only Direct Current (DC) output machines used

Welding Machine

DC negative to the torch is the industry norm

400 to 600 amp range

Duty cycle 60 to 90 per cent depending on the type of rods used

The machine must be certified as fit for purpose by a competent electrical technician.

Safety devices such as ground fault detection systems must be operational.

The machine is electrically grounded to the vessel hull

Remote voltage and amperage read out is an advantage (in dive control)

Remote amperage control is an advantage. (in dive control)

Test the output current is as indicated (Tong test or amp clamp)

Warning signs and barriers

Fire monitoring & suppression should be considered.

Consider engine exhaust location.

Welding machine Lifting Pad Eyes pull test and MPI in-date

Welding machine Slings & Shackles fit for purpose & in-date load test certificates.

Should, at a minimum, contain a positive and negative cable with an oxygen hose.

Consider a strength element of non-stretch rope such as Spectra


Equipment Yes No

Cutting Umbilical

Consider the fitting of D rings as lift points or chain stops

Cable cross section should be commensurate with the length of cable and the anticipated voltage drop. See a welding cable selection guide or low voltage electrician

Cable insulation should be of a robust nature.

Consider sheathing in areas likely to sustain damage from structure or marine growth.

It is likely that robust sheathing incurs a flexibility penalty.

Consider the last three to five meters be extra flexible welding cable.

Cable and hose should be taped every meter.

Cable should show no visible defects look for blisters, cuts and tears, wire protrusion, green staining (copper/salt residue)

The both cables should be resistance and continuity checked prior to immersion.

Electrical tests may be problematic due to water salinity, salt build up on the umbilical, water penetration of the cable sheath

Visual inspection is likely to be the best infield method of fault detection. If necessary lay the entire cable out and have it inspected. Whilst the cable is flaked out, set up for Welding. Test the cables

by having a number of welds run. If it is difficult to weld on deck there are brakes in the copper wires and strands inside the cable sheath. High resistance brakes may boil internal water generating steam and blisters

Areas of high resistance (caused by copper wire cable thinning) will get hot very quickly

The torch should be in good condition (see torch section)

The ground clamp should be in good condition.

Umbilical deployment method Pad Eyes pull test and MPI in-date

Umbilical deployment method Slings & Shackles fit for purpose and in-date load test certificates.

Cable cross section should be commensurate with the length of cable and the anticipated voltage drop. See a welding cable selection guide or low voltage electrician

Fit for purpose


Equipment Yes No

Cables Supported

Protected from dropped objects

Ground (positive) does not be through the vessel hull

Cables do not pass through areas that contain flammable substances.

Treat all styles with caution (Lenco style). Often they wear out due to internal arcing eroding the contact faces.

If they get hot during operation then the joint may be high resistance. Check the internal faces of the male and female unit for corrosion and arc pitting also the grub screw that locks the copper wire in the connector body. (Grub screw is likely to be low quality steel and subject to corrosion).

Cable connectors

Stab (Lenco style) connections should not go sub surface unless specifically designed to do be immersed in salt water.

Joints should be waterproofed using approved materials and process.

Direct Current (DC) rated.

Twin Pole solenoid operated.

Cutting & welding switch

Amperage range to suit the type of rods being used

Should be located as close to the welding machine as possible. Remote activation by the diving supervisor is preferred mode of operation.

Certified fit for purpose by a competent person

Contained in a box that prevents arc flash

Should not be in a location that is subject to elevated concentrations of oxygen or combustible gases or vapours. (Hydrocarbon, acetylene, etc.)

Knife switch style (in dive control) Mounted in a box (arc flash suppression) Handle down to open the circuit Twin Pole. Oxygen analyser in dive control if Rich Mix is being used Consider positive ventilation of dive control. Rated for the current loading of the rods being used. Dive control must be grounded with a cable equal to the size of

the welding cable. Welding Cable Bulkhead cable connectors mounted on an

non-conducting board (such as Paxolin)FMEA electrical welding ground faults: considerations may be but not limited to:

Metallic/conducting pipe work with life support functions. Electrical equipment overload (analysers) Fire Oxygen rich atmospheres.


Equipment Yes No

Planning Is the current burning work planned?

Is there a client document detailing the work scope?

Has the contractor prepared a burning procedure?

Has a risk assessment been conducted using the procedure as a guide?

Have the correct personnel been identified and represented at the risk assessment?

Representatives may be (but not limited to):Client Project team representation, Engineer, Diving Contractor Project team representation, Client Diving Rep, OIM, Vessel Master, Vessel Chief engineer, ROV, crane operators, Third party groups such as other asset owners in the same field.

Has the contractor prepared generic burning risk assessments?

Do the generic RA adequately cover the work scope?

Have the documents been reviewed?

What is the current document revision status?

Has the project plan been issued For construction?

Have the divers undergone training for the specific job?

Level 1 HIRA (onsite) to review findings of Level 2 HIRA?Do the conditions remain the same?

Can variations to the HIRA be managed on site?

Are variations managed by the contractor MOC process?

Pre-dive checks Hot Work permit in place for vessel

Hot Work permit in place for platform

Supervisor or Engineer drafts a dive plan

Divers and Others have read the Dive Plan

Tool Box Talk Includes divers and others

Knife switch Open

Sufficient oxygen

Regulator set

Oxygen hose pre-charged pressure noted.


Equipment Yes No

Inspect the Torch for condition: Large rubber washer Rod rubber washer Flash arrestor Collet condition Collet contact face condition Condition and security of the extra flexible copper cable Collet Nut threads Collet Nut

Torch trigger leak and function tested

Generator on line and set to the amperage required

Generator polarity test. Electrode should negative. Bubble test can be made by immersion of a small plate attached to

the ground lead and a rod in the Torch (remove the insulation on the test rod. Apply current the larger bubble generation will occur at the cable connected to the negative terminal.

Test the knife switch and torch with a rod test Note the amperage range

Visor in place on helmet Lens to suit water clarity No. 4, 6 or 8

Quiver full and tied shut

Spare quiver full and tied shut

Spare collets and washer on a safety pin tied three meters back from the torch

Diver has gauntlets and rubber gloves

Spare gloves tied back beside the collets

DDC checked

Cleaning equipment inspected and power equipment tested prior to deployment:

Water blaster Power or Hand wirebrush Grit Blaster Chipping hammers Scrapers

Small tools available: Hammers Dot punches Drills Hole saws Grinders Paint sticks and markers Tape measure


Equipment Yes No

Dive check Diver confirms the conditions are as predicted, or Not Review of the dive plan may be required

Burning gear is deployed Switch Open Generator Cold

Work cut site is cleaned and marked out Clean to a bright surface offers the best cutting quality and speed

Clean the back side of the cut if possible

Vent hole location(s) verified prior to cutting

Vent holes are cut and proven to the process identified in the HIRA.

Ground clamp is connected at a location safe for the diver

Diver is not to be between the ground clamp and the cutting face

Set oxygen flow by adjusting the oxygen jet from the rod to about 150 mm horizontal flow

Do not place hands in front of the rod to test oxygen pressure Do not energize cutting torch before flowing Oxygen through to

purge any possible hydrogen build up

Test cut is made on a dummy plate Supervisor verifies the current settings are within normal limits

Do not burn the rod shorter than 75 mm

Do not allow oxygen pressure to drop below 90 psi over bottom Hose burn back may occur at low oxygen pressure

Check load is supported

Safety of diver and asset is identified in the direction of cut

Assess retained energy inspect for distortion, buckling, twisting, etc.

Umbilical clear.

Post-dive checks

Electrolysis can adversely affect the integrity of the metallic parts, especially on long burning campaigns. Frequency of Inspection of the dive hat and burning equipment should be increased

63Appendix B - Training course assessment checklist

1 Purpose 64

2 Instructions, Qualifications and Experience 64

3 Teaching Facilities 65

4 Administration 69

5 Fire Prevention 70

6 First-Aid 70

7 Training Plans 71

Appendix B IOGP oxy-arc cutting training course assessment checklist


ITEM

DESC

RIPT

ION

CHEC

KS/P

ROM

PTS

Yes/ No

COM

MEN

TS

(1),

(2),

(3),

(4)

1PU

RPOS

E

This

is a

sta

ndar

dize

d ch

eckl

ist f

or a

sses

sing

trai

ning

faci

litie

s th

at p

rovid

e in

stru

ctio

n in

und

erw

ater

oxy

-arc

cut

ting

in a

ccor

danc

e w

ith th

e In

tern

atio

nal

Asso

ciat

ion

of O

il an

d Ga

s Pr

oduc

ers

(IOGP

) Rep

ort 4

71, U

nder

wat

er o

xy-a

rc c

uttin

g re

com

men

ded

prac

tice.

This

che

cklis

t has

bee

n de

velo

ped

to a

ssis

t the

ass

essm

ent t

eam

in in

terp

retin

g th

e re

com

men

ded

prac

tice

as it

rela

tes

to it

s gu

idan

ce o

n tr

aini

ng.

2IN

STRU

CTIO

NS, Q

UALI

FICA

TION

S AN

D EX

PERI

ENCE

Inst

ruct

ors

shou

ld h

ave

a th

orou

gh k

now

ledg

e an

d pr

actic

al e

xper

ienc

e in

the

subj

ects

they

are

to te

ach.

Tra

inin

g pr

ovid

ers

shou

ld h

ave

a m

etho

d fo

r ens

urin

g in

stru

ctor

s ar

e pr

ofic

ient

per

form

ing

and

inst

ruct

ing

the

rele

vant

cou

rse

task

s.

Inst

ruct

ors

shou

ld h

ave

form

al tr

aini

ng in

voca

tiona

l ins

truc

tion

tech

niqu

es.

2.1

Inst

ruct

ion

Staf

f (10

.3 C

lass

siz

es)

The

inst

ruct

or s

taff

shou

ld h

ave:

a

prim

ary

inst

ruct

or

a

Divin

g Su

perv

isor

assi

stan

t ins

truc

tors

whe

n re

quire

d Th

ere

shou

ld b

e su

ffici

ent n

umbe

r of i

nstr

ucto

rs th

at c

an p

rope

rly p

rovid

e le

ctur

ing,

pra

ctic

al a

sses

smen

t and

saf

ety

over

sigh

t sui

tabl

e to

the

clas

s si

ze. F

or

the

divin

g po

rtio

n of

the

cour

se, r

isk

asse

ssm

ent s

hall

dete

rmin

e th

e m

inim

um

num

ber o

f divi

ng s

up

Documents

Oxy-Arc Underwater Cutting Recommended Practice