Welding - a trade that underlies so many others. The base and structure of so many things - and a dangerous job.
Welding, cutting and brazing operations present a series of hazardous situations with potential exposure to burns, eye damage, electrical shock, crushed toes and fingers, and the inhalation of vapors and fumes...
29 CFR 1910.25- Required Fire Prevention Actions for Welding and Hot Work, 29CFR 1910.252 Personal protective equipment 29CFR 1926.350(d)- Gas Welding and Cutting
Causes of Welding Accidents
Many welding, cutting and brazing accidents result from:
- Inadequately trained personnel.
- Poor housekeeping practices.
- Poor shop layout.
- Inadequate lighting and ventilation.
- Improper storage and movement of compressed gas cylinders.
- Exposure of oxygen cylinders and fittings to oil or grease creating a fire or explosive hazard.
- Pointing welding or cutting torches at a concrete surface causing spattering and flying fragments of concrete.
- Electric shock when motors, generators and other electric welding equipment are not grounded.
- Inhalation of toxic fumes or vapors from welding metals or alloys.
Fires, explosions, and injuries can occur resulting from:
- The proximity of combustible solids, liquids, or dusts.
- The presence or development of possible explosive mixtures of flammable gases and air.
- The presence or nature of an oxygen-enriched atmosphere in locations where hot work is performed.
Procedures and Operating Precautions
The following provides minimum guidance on procedures and operating precautions:
- Provide ventilation in shops or rooms where work is to be performed but avoid strong drafts directed at the welding work.
- Do not place work to be welded or heated on a concrete floor. Concrete, when heated, may splatter and fly, exposing the welder to possible burns (and also throwing hot particles a considerable distance creating a potential fire hazard).
- Provide appropriate protection for welders and helpers when working on elevated surfaces. Welding areas shall be kept neat, clean, and free from tripping hazards.
- Shielding shall be provided to protect personnel from heat, sparks, slag, light, and radiation.
- Provide approved personal protective equipment for welders who must enter confined spaces, manholes or other space restricted areas. Also, provide a means to ensure their quick removal in case of an emergency.
- Do not perform cutting and welding operations in sprinklered buildings when the sprinkler system is inoperable; in explosive atmospheres or where explosive atmospheres may develop; or, within 50 feet of storage of large quantities of exposed, readily ignitable materials.
- Before lighting the torch for the first time each day, allow enough of each gas to flow through its respective hose to purge any flammable gas mixture.
- Purge hoses n open spaces and away from ignition sources. Light the torch with a friction lighter or stationary pilot flame keeping a safe distance between he torch and the welder’s hands. Point the torch away from persons or combustible materials when lighting. Do not attempt to light a torch from hot metal.
- When working in a confined space, the fuel gas and oxygen supply shall be located outside the confined space. The torch and hose should be removed from confined spaces when not in use.
- Fuel gas and oxygen torch valves shall be closed and the fuel gas and oxygen supply to the torch shall be shut off during lunch or break periods, when not in use for extended periods, and when unattended.
- Welding torch hoses must be protected from damage by contact with hot metal, open flames, corrosive agents or sharp edges. Pressure on hoses will be released at the end of each workday. Hoses must be visually inspected for damage at the beginning of each shift. Hose showing leaks, cuts, burns, worn spots or other evidence of deterioration must be repaired or replaced prior to use. Replacement hoses or fittings must be approved for use with acetylene equipment.
- A fire watch will be maintained for at least 30 minutes after completion of cutting or welding operations to detect and extinguish possible smoldering fires.
Cutting or welding shall not be permitted in the following situations:
- In areas not authorized by management.
- In sprinkled buildings while such protection is impaired.
- In the presence of potentially explosive atmospheres, e.g.. a flammable
- In areas near the storage of large quantities of exposed, readily ignitable materials.
- In areas where there is dust accumulation of greater than 1/16 inch within 35 feet of the area where welding/hot works will be conducted. All dust accumulation should be cleaned up following the housekeeping program of the facility before welding/hot works are permitted.
- Suitable extinguishers shall be provided and maintained ready for instant use.
- A fire watch person shall be provided during and for 2 hours past the completion of the welding project.
- A cutting/welding permit will be issued on all welding or cutting outside of the designated welding area.
Personal Protective Equipment
Personnel engaged in or exposed to welding, cutting, or brazing activities will be provided and use personal protective equipment to include eye and face protection, head protection when in a hard hat area, foot protection, and body, arm, and hand protection.
- Eye Protection
- Helmets shall be used during all arc welding or arc cutting operations. Goggles should also be worn during arc welding or cutting operations to provide protection from injurious rays from adjacent work, and from flying objects. The goggles may have either clear or colored glass, depending upon the amount of exposure to adjacent welding operations. Helpers or attendants shall be provided with proper eye protection. Helmets shall be arranged to protect the face, neck, and ears from direct radiant energy from the arc.
- Goggles or other suitable eye protection shall be used during all gas welding or oxygen cutting operations. Spectacles with side shields and suitable filter lenses are permitted for use during gas welding operations on light work, for torch brazing or for inspection. Goggles shall be ventilated to prevent fogging of the lenses as much as practicable.
- All operators and attendants of resistance welding or resistance brazing equipment shall use transparent face shields or goggles, depending on the particular job, to protect their faces or eyes, as required.
- Eye protection in the form of suitable goggles shall be provided where needed for brazing operations.
- All welders should wear flame-resistant gauntlet gloves and shirts with sleeves of sufficient length and construction to protect the arms from heat, UV radiation, and sparks.
- All welders should wear fire-resistant aprons, coveralls, and leggings.
- Clothing should be kept reasonably free of oil or grease. Front pockets and upturned sleeves or cuffs shall be prohibited, and sleeves and collars should be kept buttoned to prevent hot metal slag or sparks from contacting the skin.
The Safety and Health Manager shall be consulted to determine appropriate levels of respiratory protection to be worn by personnel performing welding operations.
Fire Prevention and Protection
- The welding operation environment shall be free of flammable liquids and vapors. Combustible materials within a radius of 35 feet of the operation will be protected from activity residue (flame, heat, sparks, slag, etc.).
- Firewatcher procedures shall be implemented whenever welding activities are conducted within 35 feet of combustible materials, regardless of protection provided. A qualified individual proficient in the operation of available fire extinguishing equipment and knowledgeable of fire reporting procedures shall observe welding or cutting activities. His or her duty is to detect and prevent the spread of fire produced by welding or cutting activities.
- Whenever there are cracks or other floor openings within 35 feet of the welding or cutting that cannot be closed or covered, precautions shall be taken to remove or otherwise protect combustible materials on the floor below that may be exposed to sparks. The same precautions shall be observed with regard to cracks or openings in walls, open doorways, and open or broken windows.
- Fire extinguishing equipment shall be maintained, ready for use, while welding or cutting operations are being performed. Equipment may consist of pails of water, buckets of sand, hose, or portable extinguishers depending upon the nature and quantity of the combustible material exposed.
- Where sprinkler protection exists, it shall be in full service while welding or cutting work is being performed. If welding or cutting is to be done within three feet of automatic sprinkler heads, noncombustible sheet material or damp cloth guards will be used to temporarily shield the individual heads.
- Ducts, conveyor systems, and augers that might carry sparks to distant combustibles shall be protected or shut down.
- Where cutting or welding is done near walls, partitions, ceilings, or a roof of combustible construction, fire-resistant shields or guards shall be provided to prevent ignition.
- If welding is to be done on a metal wall, partition, ceiling, or roof, precautions shall be taken to prevent ignition of combustibles on the other side, due to conduction or radiation of heat. Where combustibles cannot be relocated on the opposite side of the work, a fire watch person shall be provided on the opposite side of the work.
- Welding shall not be attempted on a metal partition, wall, ceiling or roof having a covering nor on walls having combustible sandwich panel construction.
- Cutting or welding on pipes or other metal in contact with combustible walls, partitions, ceilings, or roofs shall not be undertaken if the work is close enough to cause ignition by combustion.
Welding & Hot Work Fire Prevention Checklist
A designated welding area should be established to meet them following requirements:.
- Floors swept and clean of combustibles within 35 ft. of work area.
- Flammable and combustible liquids and material will be kept 35 ft. from work area.
- Adequate ventilation providing 20 air changes per hour, such as a suction hood system should be provided to the work area.
- At least one 10-lb. dry chemical fire extinguisher should be within access of the 35 ft. of work area.
- Protective dividers such as welding curtains or non-combustible walls will be provided to contain sparks and slag to the combustible free area.
Requirements for welding conducted outside the designated welding area.
- Portable welding curtains or shields must be used to protect other workers in the welding area.
- A hot works permit must be completed and complied with prior to welding operation.
- Respiratory protection is mandatory unless an adequate monitored airflow away from the welder and others present can be established and maintained.
- Plastic materials be covered with welding tarps during welding procedures
- Fire Watch must be provided for all hot work operations.
Welding and Cutting Pipes, Cylinders, or Containers
The procedures described below apply only to tanks too small to be entered. Compressed gas cylinders are excluded as are pipelines. Cutting and welding on containers that have held flammable liquids or gases shall be under the direct supervision of knowledgeable personnel.
BEFORE any tank, cylinder, or other container is cut, welded, or other hot work is performed, the item shall be purged or made inert. New containers shall also be made inert as they may contain a flammable preservative that could form explosive vapors when heated. Welders shall ensure that there are no substances such as grease, tars, or acids which, when subjected to heat, might produce explosive or toxic vapors. Any pipelines or connections to the drums, cylinders, tanks, or other containers shall be disconnected or blanked.
Purging and Inerting-
- Purging with Water
Where the liquid or gas previously contained is known to be readily displaced or easily soluble in water, it can be removed by completely filling the container with water and then draining. When hot work is performed on containers filled with water, extreme care shall be used to eliminate any vapor accumulation by proper venting or positioning of the container during the filling operation.
- Purging with Air
Hazardous vapors may be displaced from inside containers by purging with air. A safe atmosphere shall be maintained by continuous ventilation.
- Inerting with Gas
Inert gas may be used to displace flammable gas from the container. Adequate ventilation shall be maintained during the operation to ensure gas concentrations remain below hazardous levels.
Examples of inert gases are carbon dioxide and nitrogen.
All hollow spaces, cavities, or containers shall be vented to permit the escape of air or gases before and during preheating, cutting, or welding.
Gas Welding Safety
- Momentarily open and close (called cracking) the manifold or cylinder valves before attaching hoses or regulators. This dislodges any loose contaminant that is present.
- Release the regulator adjusting screw before opening the manifold or cylinder valve
- Open valves slowly. Don't stand in front of the regulator when opening the valve
- Don't use fuel gas from cylinders at pressure settings over 15 psi
- Purge your fuel-gas and oxygen lines
- Always light the fuel gas before opening the oxygen line
- Never use oil or grease around fuel-gas/oxygen line
- Never use oxygen as a substitute for compressed air
- Keep heat, flames, and sparks away from hoses, regulators, tanks and combustibles
- Make sure all hose, cylinder, and regulator attachments are tight and not leaking
Oxyacetylene welding equipment properly used is safe, but it has the potential for great destructive power if carelessly used
It is important that the operator be familiar with all of the potential dangers
Tips for acetylene-
- There is acetone in the cylinder and if you tip the cylinder over on its side; you will start to draw acetone out (this is the stabilizing solution for the acetylene).
- If you lay it down, stand it upright an hour before use because you will draw out the acetone.
- If too fast a rate, you will withdraw acetone.
- You might need 2 acetylene cylinders for proper flow.
Electric Welding Checklist
Perform Safety Check on all equipment
- Ensure fire extinguisher is charged and available
- Ensure electrical cord, electrode holder and cables are free from defects (no cable splices are allowed with in 10 feet of the electrode holder.
- Ensure PPE (welding hood, gloves, rubber boots/soled shoes, and aprons) are available and have no defects.
- Ensure the welding unit is properly grounded.
- All defective equipment must be repaired or replaced before use.
Remove flammables and combustibles
- No welding is permitted on or near containers of flammable material, combustible material or unprotected flammable structures.
- Place welding screen or suitable barricade around work area to provide a fire safety zone and prevent injuries to passersby (Do not block emergency exits or restrict ventilation)
Ensure Adequate Ventilation and Lighting
Execute Hot Work Permit procedures
Set Voltage Regulator
No higher than the following for:
- Manual Alternating Current Welders - 80 volts
- Automatic Alternating Current Welders - 100 volts
- Manual or automatic Direct Current Welders -100 volts
Uncoil and spread out welding cable
To avoid overheating, ensure proper contact of work leads and connections, remove any metal fragments from magnetic work clamps (to avoid electric shock do not wrap welding cables around a body part and avoid welding in wet conditions)
Fire watch for one hour after welding & until all welds have cooled
Perform final fire watch and terminate permit.
The fumes produced in a welding operation can be hazardous to the welder or workers in the near vicinity. Reducing the exposure to fumes through an effective local exhaust or area ventilation system is the first line of defense in preventing discomfort or illnesses from toxic welding fumes.
Respirators are another means of reducing exposure. This personal protective equipment should be considered a temporary process until more appropriate measures to control the exposure are in place. However, when the level of the exposure cannot be entirely eliminated by an exhaust ventilation system, some form of respiratory protection will be required when welding is performed.
Highly toxic or concentrated welding fumes may require the welder to use a supplied air hood-type respirator, no matter what type of ventilation is in place.
Testing equipment is needed to effectively evaluate the levels of toxicity welding fumes emit. Many toxic fumes are colorless and odorless, and chronic effects of overexposures may not be immediately detectable. Harmful levels of welding fumes cannot be determined by relying on your body's senses. You may see smoke in the air, smell an irritant and not be adversely affected. In order to accurately determine the level of the contaminants present, air quality testing equipment in the way of air sampling pumps are placed in the area and on the welder. This equipment pulls air through a filter for a specified amount of time. The sample is then evaluated at a laboratory to determine the levels of the exposure.
The degree of exposure present determines which type of ventilation system is most appropriate. In field locations, such as construction projects and shipyards, 'sucker' hoses can be set up to pull fumes from the welding zone. Welding booths with local exhaust hoses at each station gives the welder some flexibility and mobility in performing the operation. In situations where the welder must go to the work area (due to size, weight or the unwieldy configuration of the work piece), portable exhaust systems could be an option to consider. In some situations, laboratory-type hoods may be used for ventilation. This type of system creates a high velocity exhaust vacuum within an enclosure. Using Laboratory-type hoods allow only the welder's hands/arms in the enclosure while welding is being performed.
Protecting yourself when performing welding operations depends on your understanding of the hazards involved and the proper way to control them. Control of welding hazards includes avoiding eye injury, respiratory protection, and ventilation of the work area, protective clothing and having safe equipment to use.
Clothing made from wool, or wool blends, is generally better than cotton. Some cutting operations such as inert-gas metal arc welding will cause exposed cotton clothing to rapidly deteriorate. Leather capes, jackets, leggings, and aprons provide additional protection especially in vertical, or overhead operations. Use of dark clothing will help reduce reflected light.
All welding equipment should be inspected each day prior to use. Report any defects found in regulators, torches or electrical components to a person that is qualified to make the necessary repairs.