Hot Work Done Right
Look at safety equipment first. Does the facility have fire sprinklers, and are they in service? Are there extinguishers of the correct type? Are there extinguishers throughout the work area?
Here it is December, and we’re talking about hot work. No, we aren’t talking about working when it’s hot—but, sometimes, we have to. We’re talking about working on equipment, making it hot, and having to be careful with the heat we generate and the surrounding environment.
OSHA says hot work is work that includes “welding or cutting operations, use of spark-producing power tools, and chipping operations,” but what does that mean to you and me in the workplace?
In the normal course of events, equipment breaks and needs to be repaired. Some repairs are easy: Take the broken piece out and put the new piece in. Others are not that easy. You need to turn off the energy, lock out and tag the equipment, disassemble and remove a guard, and then another half-dozen pieces of machinery must be removed to get to the damaged section. That section cannot be removed, so it has to be repaired in place. The repairs include grinding down some edges; cutting out a section with a saw and a grinder; and then welding the new piece in place.
That is the type of hot work we will be discussing.
If the equipment were in the middle of a building with nothing else around, we wouldn’t have to worry any of our sparks from the cutting or welding would ignite flammable vapors. We wouldn’t have to worry that the heat from the repaired piece would ignite combustible materials because they were in close proximity. But that is not the real world. In the real world, you need to make these repairs in the middle of your manufacturing plant, while your production lines are running full speed, perhaps filling aerosol bottles with flammable liquids. Or you have to weld that new piece on the printing press with bundles of paper all around.
What Do I Need to Know to Be Safe?
Flammable and combustible. We don’t have enough space in this article to go into all of the definitions of what a flammable or combustible liquid is. The definition depends on the agency with which you have to comply, and that is changing. For now, OSHA defines a flammable liquid as a liquid that has a flash point of less than 100 degrees Fahrenheit (deg. F.), and combustible liquids are equal to or greater than 100 deg. F. but less than 200 deg. F.
Ignitable. Although OSHA does not define ignitables, let me define them as solids that can burn when sufficient heat is applied. Examples are paper, plastics, wallboard coverings, and wood; this also would apply to flammable metals, such as aluminum and magnesium.
Sodium and potassium also are known as flammable metals, but only if they come in contact with moisture. Aluminum, magnesium, and several others will burn furiously if heated enough.
Hot work. Expanding on OSHA’s definition, hot work means welding, brazing, cutting, soldering, thawing pipes, using heat guns, torch applied roofing and chipping operations, or the use of spark-producing power tools, such as drilling or grinding. It could also be mechanical friction from gears rubbing or a static discharge from an employee’s shoes. Flammable, combustible, or ignitable materials should be kept a minimum of 20 to 35 feet away from the hot work, or those materials should be covered with a flame-retardant covering for protection.
Hot Work Program. Companies that have flammable, combustible, or ignitable materials and need to perform hot work in and around these materials need to have a Hot Work Program. The program should:
• Be in writing
• Require an inspection of the work area before the work starts
•Have a permit signed to show that all phases of the work have been inspected and approved.
Development of the Program
Develop a written Hot Work Program that is specific for your facility. In developing the program, the safety or engineering professional who will be heading up the development should ensure all necessary precautions are discussed in the program.
Safety equipment. Look at safety equipment first. Does the facility have fire sprinklers, and are they in service? Are there extinguishers of the correct type? Are there extinguishers throughout the work area? Does maintenance have a sufficient number of backup extinguishers for use during hot work projects?
Do you have fire-retardant tarps or thin sheets of metal for covering combustible and ignitable materials?
Have your employees been trained to understand what hot work is and what has to be done before, during, and after the work is done? Do they know how to sound the alarm to summon help?
Work practices. Many companies require a minimum of 20 to 35 feet of separation between hot work and combustibles or ignitables. Other companies may require at least 50 feet of separation from flammable liquids. Still other companies require that a flammable gas meter be used to determine whether vapors are present and, if so, their concentration. If the meter reads anything other than zero, hot work would not be allowed.
Any time the sprinkler system is impaired (not working), hot work should not be permitted, except under very special circumstances— and then with extra measures of protection.
The Hot Work Program should detail how the work area is to be inspected. Floors are to be swept clean of combustibles within so many feet of the work. Combustible floors are to be wet down or covered with damp sand or fire-resistive sheets. Wall and floor openings will be covered and fire-resistive tarpaulins suspended beneath the work if hot work is performed on walls, ceilings, or open-rack flooring. Work that will be performed within 3 feet of a sprinkler head will require either metal sheeting or damp cloths, or a combination of both.
Procedures need to be developed when work will be close to smoke or heat detectors. Some companies allow them to be temporarily bagged, but the bags must be removed after the work is finished and during breaks or lunch.
Remove all flammable liquids and gases from the work area. Other combustibles, if not removed, should be protected with fire-resistive tarpaulins or metal shields.
Any hot work in confined spaces should follow confined space entry procedures first. Atmospheric monitoring during the hot work should ensure sufficient oxygen levels for the workers. Ensure that sufficient time has elapsed for purging vapors from the space before entry and/or hot work takes place.
Lockout/tagout needs to be followed, depending upon the type of work being performed. Construction is noncombustible and without combustible covering or isolation.
Hot work should not be allowed if any of the above conditions cannot be corrected or made safe.
Contractors
From a CSB report on a 2001 incident: “. . . contractors w[ere] repairing grating on a catwalk in a sulfuric acid storage tank farm when a spark from their hot work ignited flammable vapors in one of the storage tanks.” In this refinery incident, where one person was killed and eight others were injured, there was off-site environmental impact. Situations like this are all too frequent at manufacturing facilities, chemical plants, and refineries. If you have contractors working in your facility, you need to develop a contractor safety program that includes a hot work procedure and ensure it is being followed.
Whether the contractor follows your program or has his own program that he will follow needs to be worked out ahead of time. All of the contractor’s employees must know what they will be doing and also have had training in whichever program will be utilized.
Fire Watch
Another vital piece of the safety setup is the fire watch. This is a person whose only duty is to scan the hot work area looking for potential fires or hot spots. This person has a fire extinguisher and a means of communication to reach emergency service personnel. The fire extinguisher should be the correct type for the materials in the area and of a large enough size to be useful in the event of a flare-up only after the fire department has been notified.
Permit
To show that all of the above steps were checked, inspected, cleaned, or evaluated, a written permit is used. You can find examples of hot work permits on the Internet, but your permit should be developed so that it provides your personnel with the specific information they need for your facility.
This article originally appeared in the December 2008 issue of Occupational Health & Safety.