Hot work is any work, such as welding, torch cutting, or grinding, that produces enough heat to potentially start a fire. Most workplaces have hot work permitting procedures in place to prevent accidents. The following is not intended to be an exhaustive list of safety checks, nor is it intended to outline or detail an actual hot work safety policy.
Before starting any work that requires high heat, it is helpful to consider alternate ways to complete the task. A cutting torch might be the easiest way to trim the end off a steel bar, but a Sawzall could probably do the job just as well without the risk inherent in using open flame. Likewise consider if the job could be taken to a safer location, such as a workshop, rather than done on-site. Once the decision has been made to perform hot work, a number of precautions should be taken to minimize the risk of accidents. Most hot work permitting procedures require the following things to be checked off a list on the permit, and a copy of the permit to be posted at the work site.
Ensure fire safety equipment is available and in good working condition.
Fire safety equipment is equipment such as fire extinguishers, fire hoses, sprinkler systems, and other such emergency equipment. Sprinkler systems and fire hoses should have line pressure. Fire extinguishers should be inspected regularly and pressurized or charged to specifications. Make sure the available equipment is appropriate for the type of fire danger; for example a water hose is not appropriate for extinguishing a grease fire.
Ensure hot work equipment is in good working condition.
The hot work equipment itself must also be in good working condition, both to prevent fires and to prevent injury. Electric welders should have their cables inspected for cracked or broken insulation. Oxy-acetylene tanks should be pressurized to specifications and the hoses should be in good shape. The list could go on, but in general the equipment needs a basic safety inspection as appropriate for its type.
Do not work alone, have at least one other person present at all times.
Hot work, and indeed any dangerous work, should never be performed alone. A second person is useful for spotting additional dangers, some of which could be hard to see when concentrating on the task at hand. Additionally, a second person can provide assistance or go for help in the event of a serious accident that leaves the worker overcome by fumes, knocked unconscious, or otherwise incapacitated.
Check the area 35 feet around for combustible material.
An area 35 feet around the hot work location is at the most risk for catching fire, so an area at least this large should be prepared for the work. Check the area for flammable dust, combustible liquids or other material on the floor, openings or penetrations in the floor, walls, or ceiling that sparks could fall through, and other hazards. If the floor is made of combustible material, spreading wet sand around the work area is very effective at preventing ignition. If working directly on a wall, ceiling, or floor, check the other side for any combustible material. Check the atmosphere for flammable or explosive gasses and adequate ventilation, especially if the area is enclosed or confined. If working in a confined space, make sure to follow the appropriate confined space entry procedure in addition to any hot work permitting required.
Provide for a four hour fire watch.
Post-accident investigations show that the four hours following hot work are the most dangerous for unexpected fires to start. Heat retained in metal, smoldering materials, and hot equipment at the work site are just a few examples of things that could start a fire long after the work is finished. A person should be in the area for one hour after the work is complete to watch for trouble, and additional checks should be made every hour for the next three hours. Most hot work policies require the person performing the fire watch to sign the copy of the permit left at the work site at the beginning and end of the fire watch to provide documented evidence that the watch was performed.
Some of the most dangerous hot works jobs are those performed on storage tanks, drums, silos, and other bulk storage units that once contained flammable or explosive liquids or powders. Old oil drums, starch silos, chemical tanks, and other such "empty" containers actually contain small amounts of residue and fumes left behind when they were emptied. Unless these are thoroughly cleaned out, the residues and fumes in such enclosed spaces can and do explode when hot work tools are used on them.
Hot work policies are often influenced by local laws and requirements set by a workplace's insurance carrier. It is important to remember that anything recommended by an outside authority represents minimum requirements, and the actual procedure must be tailored to fit the individual workplace. No procedure can completely eliminate the risk of accidents, but a comprehensive hot work permitting procedure can cut the risk substantially.
The most common cause of breakdowns in any safety procedure is the human element. Workers should receive regular training to keep them up to date on the hot work procedures, and care should be taken to ensure they are actually performing the steps, not simply checking them off the list.