Welding and Cutting
Welding and cutting are two forms of hot work that require special safety considerations. Unless they are done in a designated shop area, welding and cutting are strictly prohibited without proper authorization.
Before conducting welding or cutting operations, inspect your equipment for the following:
- Welding leads must be completely insulated and in good condition.
- Cutting tools must be leak-free and equipped with proper fittings, gauges, regulators, and flashback devices.
- Oxygen and acetylene tanks must be secured in a safe place.
In addition, follow these guidelines for most welding and cutting procedures:
- Conduct welding and cutting operations in a designated area free from flammable materials. When welding or cutting is necessary in an undesignated or hazardous area, have someone nearby act as a fire attendant.
- Periodically check welding and cutting areas for combustible atmospheres.
- Take care to prevent sparks from starting a fire.
- Remove unused gas cylinders from the welding and cutting area.
- Keep hoses out of doorways and away from other people. A flattened hose can cause a flashback.
- Mark hot metal with a sign or other warning when welding or cutting operations are complete.
The following table provides an overview of welding and cutting hazards:
21.1 Welding Guidelines
Proper selection of personal protective equipment is very important when welding; make sure your welding helmet visor is dark enough to provide adequate protection. Wear fireproof apron and gloves. In addition, take care to protect other people from the hazards of welding. For example, use a welding curtain to protect other employees from UV radiation.
There are two types of welders:
- AC welders: These welders are used for standard welding procedures, AC welders are powered by an electrical cord.
- DC welders: These are portable welders that are commonly used in manholes. DC welders have their own power supply.
- Wire-feed welders: These welders use inert gas for light metal work (e.g., stainless steel, aluminum, etc.).
Common hazards associated with welding include the following:
- UV radiation exposure
- Oxygen depletion
- In addition to the general guidelines for welding and cutting, follow these specific guidelines for safe welding operations:
- Make sure the welding area has a nonreflective, noncombustible surface.
- Ensure that adequate ventilation and exhaust are available.
- Be aware of electrocution hazards, particularly in damp conditions. Be sure that electrical cords are properly grounded. It is advisable for cords to pull down from an overhead pulley.
21.2 Cutting Guidelines
Gas welding and cutting tools are often powered by oxygen or acetylene gas cylinders. These tanks require special safety precautions to prevent explosions and serious injuries. Follow the safety guidelines below, and refer to the Laboratory Safety chapter in this manual for more information on gas cylinders safety:
- Ensure that acetylene/oxygen systems are equipped with flame or flashback arrestors.
- Store acetylene bottles upright and secured.
- Keep cylinder fittings and hoses free from oil and grease.
- Repair or replace defective hoses by splicing. Do not use tape.
- Do not tamper or attempt to repair cylinders, valves, or regulators.
- Do not interchange regulators or pressure gauges with other gas cylinders.
- Carefully purge hoses and torches before connecting a cylinder.
- Set acetylene pressure at or below 15 psig. Always use the minimum acceptable flowrate.
- Never use a match to light a torch. Use an approved lighter.