Prevention of Cutting and Welding Fires
Cutting and welding are no doubt the number one fire hazard of industry, but it is a necessary hazard. Cutting and welding may be done safely if proper precaution is taken before the job is started.
First, let us consider some of the characteristics of a cuttin_____ or welding job. Knowing the ways in which fires may start is an important step toward preventing them. Sparks from these jobs are really small globules of molten metal which are thrown out in a heavy shower, (particularly in cutting jobs), and may be thrown for a distance of 25 or 30 feet.
Heat sufficient to start fires may come from the acetylene flame itself, but this is a rare cause of fire. Heat from the metal being cut or welded may sometimes be the cause of fires, if the pieces of metal are allowed to touch materials that burn easily. In most cases, fires are caused by sparks from the cutting and welding operations. This is more apt to happen when steel or iron is being cut than when non-ferrous materials are being cut. In the cutting of steel and iron, many times small pieces are cut away or out of larger sections and allowed to drop on the floor or ground. The smaller the piece cut away, the more heat it will have absorbed, making it more apt to ignite combustible material and flammable liquids.
Pieces of steel and iron that have been heated to a cherry-red may retain enough heat to start fires, 5 to 20 seconds or longer after they have fallen. A piece of steel or iron heated and still remaining black in color, may be hot enough to start a fire.
The globules and sparks from a cutting job are more apt to start fires in combustible material than pieces of hot metal, because the globules and sparks are at a temperature of molten steel when it falls, therefore staying hot longer; although, when globules and sparks fall from a height of 15 feet or more, they will scatter and cool more quickly than a small piece of metal dropped from the same height.
Now that we have considered the characteristics of cutting and welding as welding creates the same hazards as cutting, let us give some thought to the prevention of these fires.
The saving of a few minutes time never justifies neglect of fire prevention when the possibility of a fire or explosion may exceed a million times the minute saved. So many times foremen grumble about stopping production to take proper precaution to do a cutting job, as they wish to give the impression that they are production minded, 100%, but it is my opinion that no foreman or supervisor is 100% production minded, who neglects fire and explosion prevention or safety, as these three enemies to industry do not just happen but are caused.
Stationary cutting and welding used in regular production operations are relatively safe and they have been properly guarded against sparks coming in contact with combustible materials and flammable liquids. It is the portable equipment that causes the greatest number of fires. The safest rule to follow in preventing fires and explosions is to keep the flame, sparks and pieces of hot metal from coming in contact with combustible material and flammable liquids. Whenever it is possible to take cutting or welding work away from its normal location to a safe area, do so. Before you cut or weld in a location for the first time, be sure and contact someone who is acquainted in this area so that you will not make the mistake of overlooking some combustible material or flammable liquids. When it is possible to move combustible materials or flammable materials and liquids, do so rather than cover same, but if they cannot be moved, be sure and cover same with fire blankets or pieces of sheet metal. Be sure blankets are in good condition and that they are weighted down on floor so as to prevent soarks and globules of hot metal from rolling underneath. When blankets have to be overlapped to cover material or equipment, a good rule to follow is to roll the edges of the two blankets. This prevents sparks from getting under the top blanket, and dropping on the material or equipment being covered.
Floors should be swept clean if floor is wood and sprinkled with water. Be sure that all openings, stairways, holes and cracks in the floor, and spaces around pipes, are properly covered with fire-blankets or sheet metal so as to prevent sparks and globules of metal from falling through to floor below and igniting other combustible material and flammable liquids. In some instances, drilling of holes for bolts and rods instead of cutting might be done, especially over serious hazards such as dip and wash tanks when it is impossible to cover them properly due to other equipment involved. Another precaution to take is to catch sparks, small pieces and globules of metal in a pan or bucket of water or soapstone. This is recommended for overhead jobs, but do not rely wholly on this; still cover combustible material or flammable liquids below as you would in any other rutting or welding job.
We have considered the general rules for prevention of fires which we should do primarily, but let us now overlook the possibility of a fire occurring, so fire extinguishers must be considered. A fire that can be put out with an extinguisher or a bucket of water when it starts, but if permitted to burn a few minutes, may tax the efforts of an entire fire department.
Before cutting or welding jobs are started, all of the rules previously mentioned should be complied with: then, see that adequate fire extinguishers are available. If building is sprinkled, be sure sprinkler system is in service and remains in service while cutting and welding job is being done. Much may be said about cutting and welding jobs in regard to the proper maintenance of equipment.
Leaking hose or valves on oxygen or acetylene tanks should never be permitted on cutting or welding jobs. Care should be taken as to use of correct pressure of oxygen and acetylene. On welding jobs special care should be taken in using the correct amount of current to do the job.
If these rules are followed, excessive sparks and globules of metal will be eliminated, making a safer operation. I have spoken briefly on this subject, but if these rules are followed, am sure we will have fewer fires where cutting and welding jobs are in progress.