1.0 PURPOSE
The purpose of this procedure is to provide written instructions for the safe use of welding and burning equipment, and the proper methods of fire prevention for Nitro Construction Services
2.0 RESPONSIBILITY
It is the responsibility of the Site Manager/Superintendent or his qualified designee to implement the requirements of this procedure. All employees shall be trained before beginning work, on the proper handling, use, and transport of compressed gas cylinders.
3.0 REQUIREMENTS
29 CFR 1926.350, 351, 352, 353, 354
4.0 PROCEDURE (GAS WELDING AND CUTTING):
4.1 Transporting, Using, Moving, and Storing Compressed Gas Cylinders
4.1.1 Valve protection caps shall be in place and secured.
4.1.1.1 When a gas cylinder is to be used, and the cylinder cap cannot be removed by hand, the gas cylinder must be tagged out “Do Not Use” and placed in a designated storage area to be returned to the vendor. Do Not Use a means of mechanical advantage to try and remove Cap.
4.1.2 Compressed gas cylinders shall have clear and legible identification placed in a conspicuous location, detailing the contents of the cylinder.
4.1.3 Before using a compressed gas cylinder, a thorough visual inspection shall be completed to ensure there are no major defects in the shell of the cylinder and that there are no visible leaks.
4.1.3.1 The compressed gas cylinder inspection shall include the inspection of the attached regulators, when in use. Regulators shall be inspected for proper operation and any visual defects. There shall be no grease, oil, solvents, or dirt near the regulator.
4.1.4 Compressed gas cylinder discharge valves shall only be operated using appropriate tools and shall not be excessively tightened.
4.1.5 Compressed gas cylinders shall be secured in an upright position by use of straps, ropes, or designed rack at all times.
4.1.6 Compressed cylinders shall not be hoisted or transported utilizing magnets or choker slings.
4.1.7 When cylinders are transported by powered vehicles, they shall be secured in a vertical position.
4.1.8 Valve protection caps shall not be used for lifting cylinders from one vertical position to another.
4.1.9 A suitable cylinder truck, chain, or another steadying device shall be used to keep cylinders from being knocked over while in use.
4.1.10 Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease), a minimum distance of 20 feet or by a noncombustible barrier at least 5 feet high having a fire-resistance rating of at least one-half hour.
4.1.11 Inside of buildings, cylinders shall be stored in a well-protected, well-ventilated, dry location, at least 20 feet from highly combustible materials such as oil or excelsior.
4.1.11.1 Cylinders should be stored in defined locations away from elevators, stairs, or gangways.
4.1.11.2 Assigned storage places shall be located where cylinders will not be knocked over or damaged by passing or falling objects, or subject to tampering by unauthorized persons.
4.1.11.3 Storage areas shall be designated for Full or Empty cylinders.
4.1.11.4 Empty cylinders shall be properly marked, preferably using the designation “MT”.
4.1.11.5 Cylinders shall not be kept in unventilated enclosures such as lockers or cupboards.
4.2 Placing Cylinders
4.2.1 Cylinders shall be kept far enough away from the actual welding or cutting operation so that sparks, hot slag, or flame will not reach them. When this is impractical, fire resistant shields shall be provided.
4.2.2 Cylinders shall be placed where they cannot become part of an electrical circuit. Electrodes shall not be struck against a cylinder to strike an arc.
4.2.3 Fuel gas cylinders shall not be placed in a location where they would be subjected to open flame, hot metal, or other sources of artificial heat.
4.2.4 Cylinders containing oxygen or acetylene or other fuel gas shall not be taken into confined spaces.
4.3 Treatment of Cylinders
4.3.1 Cylinders, whether full or empty, shall not be used as rollers or supports.
4.3.2 No person other than the gas supplier shall attempt to mix gases in a cylinder. No one except the owner of the cylinder or person authorized by him shall refill a cylinder.
4.3.3 No damaged or defective cylinder shall be used.
4.3.4 If a leaking cylinder is identified, the defective cylinder shall be moved to a well-ventilated area, away from potential ignition sources. The Supplying Vendor shall be contacted to remove the cylinder.
4.4 Use of Fuel Gas
4.4.1 Employees shall be thoroughly instructed in the safe use of fuel gas, as follows:
4.4.1.1 Before a regulator to a cylinder valve is connected, the valve shall be opened slightly and closed immediately.
4.4.1.1.1 This action is termed “cracking” and is intended to clear the valve of dust or dirt that might enter the regulator. The person “cracking” the valve shall stand to one side of the outlet.
4.4.1.1.2 The fuel gas cylinder valve shall not be cracked where the gas would reach welding work, sparks, flame, or other possible sources of ignition.
4.4.1.2 The cylinder valve shall always be opened slowly to prevent damage to the regulator.
4.4.1.2.1 For quick closing, valves on fuel gas cylinders shall not be opened more than 1-1/2″ turns.
4.4.1.2.2 When a special wrench is required it shall be left in position on the stem of the valve while the cylinder is in use so that the fuel gas flow can be shut off quickly in case of an emergency.
4.4.1.3 Fuel gas shall not be used from cylinders through torches or other devices that are equipped with shut-off valves without reducing the pressure through a suitable regulator attached to the cylinder valve or manifold.
4.4.1.4 Before a regulator is removed from a cylinder valve, the cylinder valve shall always be closed and the gas released from the regulator.
4.4.1.5 When the valve on a fuel gas cylinder is opened, and there is found to be a leak around the valve stem, the valve shall be closed and the gland nut tightened. If this action does not stop the leak, the use of the cylinder shall be discontinued, and it shall be properly tagged and removed from the work area.
4.4.1.6 If a leak should develop at a fuse plug or other safety device, the cylinder shall be removed from the work area.
4.5 Fuel Gas and Oxygen Manifolds
4.5.1 Fuel gas and oxygen manifolds shall bear the name of the substance they contain in letters at least 1-inch high which shall be either painted on the manifold or a sign permanently attached to it.
4.5.2 Fuel gas and oxygen manifolds shall be placed in safe, well-ventilated, and accessible locations. They shall not be located within enclosed spaces.
4.5.3 Manifold hose connections, including both ends of the supply hose that lead to the manifold, shall be such that the hose cannot be interchanged between fuel gas and oxygen manifolds and supply header connections.
4.5.4 When not in use, manifold and hose connections shall be capped.
4.5.5 Nothing shall be placed on top of a manifold, when in use, which will damage the manifold or interfere with the quick closing of the valves.
4.6 Hose
4.6.1 Fuel gas hose and oxygen hose shall be easily distinguishable from each other. The contrast may be made by different colors or by surface characteristics readily distinguishable by the sense of touch. A single-hose having more than one gas passage shall not be used.
4.6.2 When parallel sections of oxygen and fuel gas hose are taped together, not more than 4 inches out of 12 inches shall be covered by tape.
4.6.3 All hose in use carrying acetylene, oxygen, natural or manufactured fuel gas, or any gas or substance which may ignite or enter into combustion, or be in any way harmful to employees, shall be inspected at the beginning of each work shift.
4.6.4 Defective hoses shall be removed from service.
4.6.4 Hose which has been subject to flashback, or which shows the existence of severe wear or damage, shall be tested to twice the normal pressure to which it is subject, but in no case less than 300 psi. Defective hose, or hose in doubtful condition, shall not be used.
4.6.5 Hose couplings shall be of the type that cannot be unlocked or disconnected using a straight pull without rotary motion.
4.6.6 Hoses, cables, and other equipment shall be kept clear of passageways, ladders, and stairs.
4.7 Torches
4.7.1 Clogged torch tip openings shall be cleaned with suitable cleaning wires, drills, or other devices designed for such purpose.
4.7.2 Torches in use shall be inspected at the beginning of each working shift for leaking shut-off valves, hose couplings, and tip connections. Defective torches shall not be used.
4.7.3 Torches shall be lighted by friction lighters and not by matches, cigarette lighters, or from hot work.
4.8 Regulators and Gauges
4.8.1 Oxygen and fuel gas pressure regulators, including their related gauges, shall be in proper working order while in use.
4.9 Oil and Grease Hazards
4.9.1 Oxygen cylinders and fittings shall be kept away from oil or grease.
4.9.2 Cylinders, cylinder caps and valves, couplings, regulators, hose, and apparatus shall be kept free from oil or greasy substances and shall not be handled with oily hands or gloves.
4.9.3 Oxygen shall not be directed at oily surfaces, greasy clothes, or within a fuel oil or other storage tank or vessel.
5.0 PROCEDURE (ARC WELDING AND CUTTING)
5.1 Manual Electrode Holders
5.1.1 Only manual electrode holders which are specifically designed for arc welding and cutting, and are of a capacity capable of safely handling the maximum rated current required by the electrodes, shall be used.
5.1.2 Any current-carrying parts passing through the portion of the holder which the arc welder or cutter grips in his hand, and the outer surfaces of the jaws of the holder, shall be fully insulated against the maximum voltage encountered to ground.
5.2 Welding Cables and Connectors
5.2.1 All arc welding and cutting cables shall be of the completely insulated, flexible type, capable of handling the maximum current requirements of the work in progress, taking into account the duty cycle under which the arc welder or cutter is working.
5.2.2 Only cable free from repair or splices for a minimum distance of 10 feet from the cable end to which the electrode holder is connected shall be used, except that cables with standard insulated connectors or with splices whose insulating quality is equal to that of the cable are permitted.
5.2.3 When it becomes necessary to connect or splice lengths of cable one to another, substantially insulated connectors of capacity at least equivalent to that of the cable shall be used. If connections are affected utilizing cable lugs, they shall be securely fastened together to give good electrical contact, and the exposed metal parts of the lugs shall be completely insulated.
5.2.4 Cables in need of repair shall not be used.
5.3 Ground Returns and Machine Grounding
5.3.1 A ground return cable shall have a safe current carrying capacity equal to or exceeding the specified maximum output capacity of the arc welding or cutting unit that it services. When a simple ground return cable services more than one unit, its safe current carrying capacity shall equal or exceed the total specified maximum output capacities of all the units that it services.
5.3.2 Pipelines containing gases or flammable liquids, or conduits containing electrical circuits, shall not be used as a ground return.
5.3.3 When a structure or pipeline is employed as a ground return circuit, it shall be determined that the required electrical contact exists at all joints.
5.3.4 When a pipeline or structure is continuously employed as a ground return circuit, all joints shall be bonded, and periodic inspections shall be conducted to ensure that no condition of electrolysis or fire hazard exists under such use.
5.3.5 The frames of all arc welding and cutting machines shall be grounded either through a third wire in the cable containing the circuit conductor or through a separate wire which is grounded at the source of the current.
5.3.6 All ground connections shall be inspected to ensure that they are mechanically strong and electrically adequate for the required current.
5.4 Operating Instructions
5.4.1 All affected employees shall be instructed in the safe means of arc welding and cutting as follows:
5.4.1.1 When electrode holders are to be left unattended, the electrodes shall be removed and the holders shall be so placed or protected that they cannot make electrical contact with employees or conducting objects.
5.4.1.2 Hot electrode holders shall not be dipped in water. To do so may expose the arc welder or cutter to electric shock.
5.4.1.3 When the arc welder or cutter needs to leave his work or to stop work for any appreciable length of time, or when the arc welding or cutting machine is to be moved, the power supply switch to the equipment shall be opened.
5.4.1.4 Any faulty or defective equipment shall be reported to the supervisor and shall not be used until it has been repaired or replaced.
6.0 FIRE PREVENTION
6.1 Whenever practicable, all arc welding and cutting operations shall be shielded by noncombustible or flameproof screens which will protect employees and other persons working in the vicinity from the direct rays of the arc.
6.2 When practical, objects to be welded, cut or heated shall be moved to a designated safe location or, if the objects to be welded, cut, or heated cannot be readily moved, all movable fire hazards in the vicinity shall be taken to a safe place, or otherwise protected.
6.3 If the object to be welded, cut, or heated cannot be moved, and if all fire hazards cannot be removed, positive means shall be taken to confine the heat, sparks, and slag, and to protect the immovable fire hazards from them.
6.4 No welding, cutting, or heating shall be done where the application of flammable compounds or heavy dust concentrations create a fire or explosion hazard.
6.5 Suitable fire extinguishing equipment shall be immediately available in the work area and shall be maintained in a state of readiness for instant use.
6.6 Fire Watch
6.6.1 When the welding, cutting, or heating operation is such that normal fire prevention precautions are not sufficient, additional personnel shall be assigned to guard against fire while the actual welding, cutting, or heating operation is being performed and for a sufficient period after completion of work to ensure that no possibility of fire exists.
6.6.2 Such personnel shall be instructed as to the specific anticipated fire hazards and how the firefighting equipment provided is to be used.
6.6.3 Fire watches shall be required when:
6.6.3.1 Combustible material is within 35 ft of the potential fire source
6.6.3.2 Combustible material is located over 35 ft but may be easily ignited
6.6.3.3 Wall or floor openings are within 35 ft with exposed combustible materials
6.6.3.4 Combustible materials are adjacent to opposite sides of metal partitions, walls, or roofs
6.6.4 Fire watch shall be maintained at the site for at least 30 minutes after the welding or cutting operation is complete.
6.7 When welding, cutting, or heating is performed on walls, floors, or ceilings, and since direct penetration of sparks or heat transfer may introduce a fire hazard to an adjacent area, the same precaution shall be taken on the opposite side as are taken on the side on which the welding is being performed.
6.8 For the elimination of possible fire in enclosed spaces as a result of gas escaping through leaking or improperly closed torch valves, the gas supply to the torch shall be positively shut off at some point outside the enclosed space whenever the torch is not to be used or left unattended for a substantial period. Overnight and at the change of shifts, the torch and hose shall be removed from the confined space.
6.9 Except when the contents are being removed or transferred, drums, pails, and other containers that contain or have contained flammable liquids shall be kept closed. Empty containers shall be removed to a safe area apart from hot work operations or open flames.
6.10 Drums, containers or hollow structures that have contained toxic or flammable substances shall, before welding, cutting, or heating is undertaken on them, either be filled with water or thoroughly cleaned of such substances and ventilated and tested.
6.11 Before heat is applied to a drum, container, or hollow structure, a vent or opening shall be provided for the release of any built-up pressure during the application of heat.
6.12 If the requirements stated above of this section cannot be followed, then welding and cutting shall not be performed.
6.13 A Cutting, Welding and Burning permit (NCS Form 035) should be issued (either by site supervision or by the client) for areas where there are spark and/or flame producing operations. Permits may be waived by the safety representative when there is no evidence of a potential fire in the areas (e.g. all-steel rooms with no combustibles or flammables present).
7.0 VENTILATION AND PROTECTION IN WELDING, CUTTING, AND HEATING
7.1 Mechanical Ventilation
7.1.1 Mechanical ventilation shall consist of either general mechanical ventilation systems or local exhaust systems.
7.1.2 General mechanical ventilation shall be of sufficient capacity and so arranged as to produce the number of air changes necessary to maintain welding fumes and smoke to within safe limits.
7.1.3 Local exhaust ventilation shall consist of freely movable hoods intended to be placed by the welder or burner as close as practicable to the work. This system shall be of sufficient capacity and so arranged as to remove fumes and smoke at the source and keep the concentration of them in the breathing zone within safe limits.
7.1.4 Contaminated air exhausted from a working space shall be discharged in the open air or otherwise clear of the source of the intake air.
7.1.5 All air replacing that withdrawn shall be clean and respirable.
7.1.6 Oxygen shall not be used for ventilation purposes, comfort cooling, blowing dust from clothing, or for cleaning the work area.
7.2 Welding, Cutting, and Heating in Confined Spaces
7.2.1 Except as provided in paragraph 7.2.2 and paragraph 7.3.1 either general mechanical or local exhaust ventilation meeting the requirements of section 7.1 shall be provided when welding, cutting, or heating is performed in a confined space.
7.2.2 When sufficient ventilation cannot be obtained without blocking the means of access, employees in the confined space shall be protected by air line respirators, and an employee on the outside of such a confined space shall be assigned to maintain communication with those working within it and to aid them in an emergency.
7.2.3 Where a welder must enter a confined space through a manhole or other small opening, means shall be provided for quickly removing him in case of an emergency. When safety harnesses and lifelines are used for this purpose they shall be so attached to the welder’s body that his body cannot be jammed in a small exit opening. An attendant with a pre-planned rescue procedure shall be stationed outside to observe the welder at all times and be capable of putting rescue operations into effect.
7.3 Welding, Cutting, or Heating of Metals of Toxic Significance
7.3.1 Welding, cutting, or heating in any enclosed spaces involving the metals specified in this section shall be performed with either general mechanical or local exhaust ventilation meeting the requirements of section 7.1.
7.3.1.1 Zinc-bearing base or filler metals or metals coated with zinc-bearing materials.
7.3.1.2 Lead base metals.
7.3.1.3 Cadmium-bearing filler materials.
7.3.1.4 Chromium-bearing metals or metals coated with chromium-bearing materials.
7.3.2 Welding, cutting, or heating in any enclosed spaces involving the metals specified in this section shall be performed with local exhaust ventilation per the requirements of section 7.1, or employees shall be protected by air-line respirators.
7.3.2.1 Metals containing lead, either then as an impurity or metals coated with lead-bearing materials.
7.3.2.2 Cadmium-bearing or cadmium-coated base metals.
7.3.2.3 Metals coated with mercury-bearing metals.
7.3.2.4 Beryllium-containing base or filler metals. Because of high toxicity, work involving beryllium shall be done with both local exhaust ventilation and airline respirators.
7.3.3 Employees performing such operations in the open air shall be protected by filter type respirators, except that employees performing such operations on a beryllium-containing base or filler metals shall be protected by air-line respirators.
7.3.4 Other employees exposed to the same atmosphere as the welders or burners shall be protected in the same manner as the welder or burner.
7.4 Inert-Gas Metal-Arc Welding
7.4.1 Since the inert-gas metal-arc welding process involves the production of ultra-violet radiation of intensities of 5 to 30 times that produced during shielded metal-arc welding, the decomposition of chlorinated solvents by ultra-violet rays, and the liberation of toxic fumes and gases, employees shall not be permitted to engage in, or be exposed to, the process until the following special precautions have been taken:
7.4.1.1 The use of chlorinated solvents shall be kept at least 200 feet, unless shielded, from the exposed arc, and surfaces prepared with chlorinated solvents shall be thoroughly dry before welding is permitted on such surfaces.
7.4.1.2 Employees in the area not protected from the arc by screening shall be protected by filter lenses meeting the requirements of Subpart E of 29 CFR 1926. When two or more welders are exposed to each other’s arc, filter lens goggles of a suitable type shall be worn under welding helmets. Hand shields to protect the welder against flashes and radiant energy shall be used when either the helmet is lifted or the shield is removed.
7.4.1.3 Welders and other employees who are exposed to radiation shall be suitably protected so that the skin is covered completely to prevent burns and other damage by ultra-violet rays. Welding helmets and hand shields shall be free of leaks and openings, and free of highly reflective surfaces.
7.4.1.4 When inert-gas metal-arc welding is being performed on stainless steel, the requirements of section 7.3.2 shall be met to protect against dangerous concentrations of nitrogen dioxide.
7.5 General Welding, Cutting, and Heating
7.5.1 Welding, cutting, and heating not involving conditions or materials described in sections 7.2, 7.3, and 7.4 may normally be done without mechanical ventilation or respiratory protective equipment, but where, because of unusual physical or atmospheric conditions, an unsafe accumulation of contaminants exists, suitable mechanical ventilation or respiratory protective equipment shall be provided.
7.5.2 Employees performing any type of welding, cutting, or heating shall be protected by suitable eye protective equipment per the requirements of 29 CFR 1926 Subpart E and shall always have first aid equipment available.
8.0 WELDING, CUTTING, AND HEATING IN WAY OF PRESERVATIVE COATINGS
8.1 Before welding, cutting, or heating is commenced on any surface covered by a preservative coating whose flammability is not known, a test shall be made by a competent person to determine its flammability. Preservative coatings shall be considered to be highly flammable when scrapings burn with extreme rapidity.
8.2 Precautions shall be taken to prevent the ignition of highly flammable hardened preservative coatings. When coatings are determined to be highly flammable, they shall be stripped from the area to be heated to prevent ignition.
8.3 Protection against toxic preservative coatings:
8.3.1 In enclosed spaces, all surfaces covered with toxic preservatives shall be stripped of all toxic coatings for a distance of at least 4 inches from the area of heat application, or the employees shall be protected by air-line respirators.
8.3.2 In the open air, employees shall be protected by a respirator per Subpart E of 29 CFR 1926.
8.3.3 The preservative coating shall be removed a sufficient distance from the area to be heated to ensure that the temperature of the unstripped metal will not be appreciably raised. Artificial cooling of the metal surrounding the heating area may be used to limit the size of the area required to be cleaned.
9.0 APPENDICES
9.1 NCS Form 035 – Cutting, Welding, and Burning Permit