SAFETY IN GAS CUTTING AND WELDING OPERATIONS

General HSE Considerations

  Preparatory Work

All gas cutting and welding work are categorized as “Hot Work”. A PTW for “Hot Work shall be applied for and approved by the Person in Charge at the work site prior to the commencement of work. For welding or cutting inside new vessels, old vessels and equipment, additional Confined Space Entry PTW shall be obtained and shall be used together with the Hot Work PTW.

All personnel involved in Hot Work shall undergo a briefing on Gas Cutting & Welding Safety before they commence their work. Welders and burners shall be skilled tradesmen. Apprentices and helpers shall work under the supervision of a qualified person.

Work sites

• Welding and cutting equipment shall be placed so that it does not create a hazard in passageways, on ladders or on stairways.
• Warning signs for eye protection shall be placed at designated welding and cutting areas. Protection from heat, welding arcs, and welding spatter shall be provided around designated welding and cutting areas. This is typically in the form of fire-resistant screens, which provide protection while allowing air circulation.
• Walls adjacent to designated areas shall be painted to reduce the reflection of ultraviolet light.
• Welding and cutting shall be carried out in designated areas designed to minimize the risk of fires.
• Where the work cannot be moved, work areas shall be made safe by moving combustible materials to a safe location.
• Welding and cutting shall not be carried out unless the surrounding atmosphere is free of flammable gas.
• Fire resistant sheeting or damp sand shall be used to cover combustible floors. Additional protection shall be provided to prevent electric shocks if floors are wet. Openings in floors and walls shall be covered to prevent the possibility of sparks igniting fires in adjacent areas.

Understanding the Hazards and Consequences

Various hazards are associated with welding and cutting, but as in other operations, they can be controlled by appropriate preventive measures. Unless these measures are taken, the hazardous situations can easily give rise to personal injury and/or material damage. All personnel involved in such work, shall, therefore, be aware of these risks whilst doing their work.

Some typical hazards are:

• The brilliant light of an arc
• The heat of an arc, molten metal, sparks, hot objects, etc.
• Toxic fumes released during the welding/cutting process
• Fuel gases that are stored in gas cylinders.
• High amperage electrical energy that is stored in the cables and welding generators/rectifiers

The consequences that can result from the release of these hazards are;

• Fire resulting in burns, equipment damage
• Explosions resulting in damaged equipment and fatalities
• Exposure to toxic fumes resulting in breathing difficulties, long-term lung damage and possible fatalities
• Heat burns
• Eye damage due to exposure to radiating light of welding arc leading to headaches and long-term blindness
• Electrical shocks leading to partial/permanent disabilities or fatalities

 Fire Watchers

• A fire watcher is required for all welding and cutting jobs carried out at the worksite.
• Fire watchers shall be competent in the use of fire extinguishers and emergency response and shall not be assigned to other duties while they are on fire watch duty.
• The fire watcher shall remain in the immediate area at all times work is in progress.
• The fire watcher shall have two dry powder or carbon dioxide fire extinguishers available at the worksite.
• The fire watcher shall:

o Be at the work site throughout the welding and cutting.

o Ensure that sparks do not fall into unprotected areas such as drains containing hydrocarbons or flammable material.

o Ensure a source of running water is available for immediate use throughout the job.

o Ensure nearby materials do not catch fire.

o Ensure that drainage from the area is not restricted and there is no possibility of hydrocarbon accumulation.

o Warn the welder of any hazard developing in the work area.

o Isolate welding equipment in the event of an emergency.

o Initiate emergency response in the event of emergencies.

o Continue to monitor the work area for 30 minutes after completion of work to ensure that fires do not start.

 Ventilation

• Adequate ventilation must be provided for all welding and cutting activities to limit exposure to the hazardous dust and vapours produced.
• Natural ventilation is acceptable for welding, cutting and related processes provided precautions are taken to keep the operator away from the welding fumes.
• Where the natural ventilation is insufficient mechanical ventilation comprising local exhaust or forced ventilation shall be provided.

 Waste Disposal

On completion of gas cutting or welding work, the waste generated shall be disposed off as per the site Hazardous Waste Management procedure requirements. Waste such as spent electrodes, welding slag, dust and contaminated welding gloves shall be treated as hazardous waste. Other waste generated can be treated as domestic waste and managed as per the Site Domestic Waste and Sewage Management procedure.

Specialized Personal Protective equipment

 Heads and eyes

• Safety Helmets and shields that protect the operator’s face and head from heat, light and weld spatter shall be used. It is preferred that the welding shields fixed to the safety helmets are used for welding work
• The shields that are used shall:

􀂃 Be thermally insulating, electrically insulating and non-combustible

􀂃 Be able to absorb visible and non-visible light.

􀂃 Be fitted with suitable filter lenses and cover plates to protect the filter lens

􀂃 Be fitted with a window that allows easy replacement of the plates

􀂃 Have outer cover plates that are impact resistant and made of clear glass or self-extinguishing plastic

• Materials in contact with the body must be non-irritating and be capable of being disinfected.
• During arc welding or cutting, goggles or safety spectacles with side-shields must be worn under the helmet or hand shield
• Goggles lenses may be clear or colored, depending on the amount of exposure to adjacent welding or cutting radiation. Ventilation slots on cup type goggles must have baffles to prevent light from entering.
• Caps shall be worn under helmets to prevent head burns.

 Hands

• The welders and helpers shall wear flame retardant and heat resistant welding gloves.

Body

• Suitable protective clothing shall be worn during all welding and cutting activities to provide protection from sparks, weld spatter and radiation
• The clothing shall be of fire resistant material
• Aprons shall be used to protect the front of the body when there is a potential of extensive weld spatter generated during welding
• Additional leg protection shall be used when there is high potential for the legs to be affected by weld spatter and heat
• For overhead welding work capes with sleeves or shoulder covers shall be used

 Nose

• Where the ventilation is insufficient to prevent the welders and helpers breathing toxic fumes generated, approved respirators as specified in the PTW shall be used.
• When welding or cutting metals with hazardous coatings such as galvanized metal the operator should use a supplied-air type respirator or a respirator specially designed to filter the specific metal fume.
• Respirators shall be used when working with welding rods coated with flux.
• Respirators shall also be used when welding materials containing fluorine compounds, zinc, lead, beryllium, cadmium, and mercury.

• Respirators shall also be used when cleaning and degreasing metals to be welded with hazardous compounds. Refer to Chemical safety Data sheets when these compounds are used with regards to the precautions to be taken

 Feet

• All welders and helpers shall wear high cut safety boots that protect the ankles and shins from welding splatter

 Special HSE Considerations

 Cutting & Welding using Gas

 Gas Cylinders

Gas used for cutting and gas welding comprises a mixture of Oxygen and Acetylene or Propane. The gases are contained in cylinders and special precautions have to be taken to ensure that the gases do not leak and lead to hazardous conditions that result in catastrophic consequences.

The following precautions shall be adhered to when dealing with gas cylinders:

• Cylinders should be stored in areas specially defined for the purpose, outdoors, away from all sources of heat and away from elevators, gangways and other traffic hazards. Oily rags, waste and other refuse should not be allowed to accumulate on or near stored cylinders. Cylinders should be protected against extremes of weather and direct radiation from the sun or hot equipment.
• Fuel gas cylinders should be placed with valve end up whenever they are in use.
• A cradle, boat or similar platform closed on all sides, should be used when cylinders are transported by crane or derrick. Slings or electric magnets should never be used for this purpose.
• When cylinders are moved by hand, they may be tilted and rolled on their bottom edges. Dragging and sliding should be avoided. When cylinders are transported by vehicle they should be secured in position. Cylinders should not be dropped nor should they be permitted to strike violently against anything.
• Valve-protection caps should not be used for lifting cylinders from one vertical position to another. Bars should not be used under valves or valve protection caps to pries cylinders loose when they have become frozen to the ground or otherwise fixed. The use of warm water is recommended for this purpose.
• Cylinders shall be secured with a suitable steadying device to prevent their being knocked over.
• Cylinders in use shall be kept far enough away from the welding or cutting operation to prevent their coming into contact with sparks, hot slag, hot metal or flame.
• Cylinders shall not be placed where they might become part of an electric circuit. Contact with radiators, piping systems, layout tables rails or trolley wires shall be avoided. Never strike an arc against a cylinder.
• Cylinders should not be placed under structures where valves could be damaged by falling objects.
• Oxygen and fuel cylinders shall be colour coded to prevent incorrect identification.
• Empty cylinders should be marked and segregated from full cylinders for return to the supplier.
• Valves on empty cylinders should be closed and fitted with valve protection caps.
• Cylinder valves should be closed, and the valve protection cap should be in place, hand- tight, when cylinders are not in use.

• If a valve leak develops, the cylinder should be removed from service, suitably tagged, placed outdoors, with an appropriate warning sign, away from any source of ignition, and the supplier notified.
• Cylinders should only be re-filled by authorized persons or suppliers

Cylinder Valves and Regulators

• Before a gas cylinder is put into service, the valve shall be opened slightly then closed immediately. This action is known as "cracking" the valve, and is intended to clear the valve of dust or dirt that might otherwise enter the regulator. Valves on gas cylinders shall not be cracked near welding work, sparks, flames or other sources of ignition. The operator shall stand on the far side of the cylinder from the outlet when cracking the valve.
• After the cylinder valve has been "cracked" the regulator shall be connected to the cylinder and tightened with the correct size open-end spanner. Adaptors are required to attach some acetylene regulators to the valves. Soapy water shall be used to check for leaks at the connections between the regulators, adaptors, and cylinder valves. Care should be taken to avoid getting oil or grease on the fittings when connecting an oxygen regulator.
• All gas cylinder valves shall be opened gradually to prevent a sudden surge of high pressure until the required pressure has been attained.
• Only gas supplier recommended pressure-reducing regulators shall be used on the gas cylinders. Regulators shall be returned to the supplier for repair, calibration or adjustment. To ensure their accuracy, gauges attached to the regulators should be tested periodically. Oil shall never be used to test the accuracy of gauges used oil oxygen cylinders. Faulty seats in the unions on regulators may result in gas leaks. Damaged unions shall be removed and replaced to prevent any gas leaks.
• If the low-pressure gauge on the regulator shows a continuous and steady increase in pressure when the torch valves are closed, the cylinder valve shall be closed immediately and the regulator repaired.

Hoses and Connectors

• Only welding hoses that meet Rubber Manufacturers Association and Compressed Gas Association standards in the size and grade suitable for both the conditions and gases shall used. Grades R & RM are designated for acetylene use only. Grade T may be used with all fuel gases.
• Hoses are manufactured in distinctive colours for ready identification. Red is the generally recognized colour for fuel-gas hoses, and green for oxygen hoses. Those connections on the regulator shall be similarly marked for identification.
• Hoses shall be protected from kinking or tangling and from being stepped on, run over by trucks, or otherwise damaged by taping the hoses together and providing protective covering if they have be laid across pathways.
• Hoses shall be protected from flying sparks, hot slag, and falling objects.
• Contact of the hoses with oil or grease shall be avoided to reduce deterioration of the rubber.

• Spare hoses shall be stored in a cool place, and away from direct sunlight to reduce the deterioration of the rubber through ageing.
• Before a new hose is put into service, the fine talc dust on the inside should be blown out to prevent any clogging of the torch valves.
• Damaged or worn out shall not be used. They shall be replaced wholly or the damaged portion cut and removed.
• Hoses with more than one splice per 50-foot (15 m) section shall not be used. For joining cut hoses select fittings with adequate inside diameter to avoid flow restrictions.
• A "flashback arrester" shall be installed between the cylinders and hoses immediately after the pressure regulators to prevent any reverse flow of oxygen into the fuel gas hose (or fuel into the oxygen hose), producing an explosive mixture in the hose.
• Hoses shall be connected by means of approved fittings and securely fastened with clamps in such a manner as to withstand a pressure of twice the maximum delivery pressure downstream of the regulator without leakage.
• Hose connections shall be as per Compressed Gas Association standard CGA E-1 - Standard Connections for Regulator Outlets, Torches and Fitted Hose for Welding and Cutting Equipment.
• All connections shall be leak tested using soapy water or other safe means.

 Gas Torches and Blowpipes

• The fuel gas valves should always be closed before the oxygen valve on the torch is to be opened for adjustment of pressure.
• When a cutting torch is used, both the oxygen valve and the cutting valve on the torch must be open while oxygen pressure in being regulated. There upon the oxygen valve on the torch should be closed. Oxygen pressures should not exceed those recommended by the manufacturer of the equipment.
• Only a friction lighter, stationary pilot flame, or other similar source of ignition should be used to light the torch. No attempt should be made to light or relight a torch from hot metal. Using matches to light the torch brings fingers too close to the tip.
• The flame is extinguished by closing the oxygen valve and then the fuel-gas valve.
• Momentary retrogression or burning back of the flame into the torch tip may result in backfire or pre-ignition which causes the flame to go out with a loud snap or pop. No adjustment of the torch valves is required. This backfiring is usually the result of improper handling of the torch such as touching the tip against the material being welded, overheating the tip, operating the torch at other than recommended gas pressures, or a loose tip.
• Correct delivery pressures of oxygen and the fuel gas shall be maintained to prevent flashbacks at the torch ends.
• A torch shall not be relight after a flashback until it has been thoroughly examined for damage.

 Arc Welding

The potential hazards that can be present during arc welding activities include toxic fumes, dusts, burns, fires, explosions, electric shock, radiation, noise, and heat stress. Any of these hazards can result in injury or death. These risks shall be eliminated or minimized by following the HSE precautions listed.

 Selection of the Arc Welding set

• Arc welders are typically ACDC, 240/415-volt transformer types or DC rectifiers using electricity as the energy source. Portable welders are of the diesel/gasoline engine powered type.
• Arc welding sets shall comply with National Electric Manufacturers Association (NEMA) standards or the safety standards for arc welders as determined by the Underwriters Laboratories (UL).

Installation of the Arc Welding set

• Before the installation of electric arc welding sets, the electrical system shall be checked to determine if it is adequate to handle the increased load required by the welding set. The Competent Electrical Person shall be consulted for this.
• The frame or case of the welding set shall be properly grounded.
• A safety-type disconnecting switch or controller shall be located near the machine.
• The welding set or sets used shall be protected by a properly sized fuse or circuit breaker on an independent circuit.

 Safe operation of the Welding set

• No welding, cutting, or hot work shall be attempted on used drums, barrels, tanks, or other containers since they may contain remnants of toxic, flammable or explosive materials.
• If possible, work to be welded shall be placed on a firebrick surface at a comfortable height.
• Welding shall never be done directly on a concrete floor. Heat from the arc can cause steam to build-up in the floor that could cause an explosion.
• The welding cables should be positioned so that sparks and molten metal will not fall on them. They should also be kept free of grease and oil and located where they will not be driven over.
• Welding cables shall be inspected before use to ensure the insulation is good. Cables with damaged insulation shall not be used.
• For welding to be done on steel or other conductive material an insulating mat shall be used by the operator. If the welding area is wet or damp or the operator is actively perspiring then he/she shall wear rubber gloves under the welding gloves.
• It is easier and safer to establish an arc on a clean surface than a dirty or rusty one. Therefore, metal shall always be thoroughly cleaned by wire brushing or another method prior to welding.
• When chipping slag or wire brushing the finished bead the operator shall always be sure to protect his eyes and body from flying slag and chips.
• Unused electrodes and electrode stubs shall not be left on the floor as they create a slipping hazard.
• Hot metal shall be handled with metal tongs or pliers. When quenching hot metal in water it shall be done carefully to prevent painful burns from the escaping steam. Any metal left to cool should be carefully marked "HOT" with soapstone.
• When welding is finished for the day or suspended for any length of time electrodes shall be removed from the holder. The holder shall be placed where no accidental contact could occur, and the welding set shall be disconnected from the power source.

 Safety Precautions for Engine Powered Welding sets

• The welding set shall always be operated in an open well-ventilated area or the engine exhaust shall be vented directly outdoors.
• The engine shall not be filled with fuel while running or in the presence of an open flame.
• Spilled fuel shall be wiped up immediately and the fumes shall be allowed to disperse before starting the engine.
• The radiator pressure cap from liquid cooled engines shall not be removed while they are hot to prevent scalding.
• The engine shall be stopped before performing any maintenance or troubleshooting. The ignition system shall be disabled to prevent accidental start of the engine.
• All guards and shields shall be kept in place.
• Hands, hair, and clothing shall be kept away from moving parts.