Sometimes it’s necessary to cut or weld, or hot work, in the vicinity of your dust collector. However, this can be extremely dangerous if your dust is explosive. A dust collector, after all, is an accumulation of dust, and if that material is combustible, careless hot work could lead to a catastrophic explosion.
“Hot work” is defined by OSHA as “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”. While most of us would think twice about welding or cutting in the vicinity of the dust collector or any other combustible dust, using a spark-producing tool, even one that shouldn’t produce sparks but has faulty wiring, can lead to a fire or explosion.
No hot work should be done near the dust collector without the correct procedures (see NFPA 51B). This is the NFPA standard that specifically defines the procedures for conducting hot work anywhere that it might cause an explosion.
Hot work near or on a dust collector might include repairs, adding or removing a piece of equipment or ductwork, or any number of other projects. Before any of this kind of work is done around the dust collector, you must have a hot work procedure IN WRITING:
- Must be in writing and available to anyone conducting hot work in the area
- Must specify that an inspection of the work area is required before the work starts
- Must have a permit signed to show that all phases of the work have been inspected and approved
The program should assess safety equipment in the area. On a dust collector that might include a spark arrestor, spark detector, fire suppression or sprinkler system, abort gate, explosion venting, or other types of fire and explosion safety devices.
Hot work may require completely blocking the ductwork to the dust collector, or if the hot work is on or close to the collector, may require removing the filters, emptying or removing the hoppers, and thoroughly cleaning the entire dirty air side of the dust collector. It is strongly recommended that a fire suppression system be in place before hot work begins to suppress any fires that might start, and that if the dust is explosively combustible, as much of it as possible has to be removed.
NFPA 51B specifies that once the area has been inspected and determined to be safe for hot work, the company safety specialist will issue a permit for work to proceed. It’s the job of this designated safety specialist to inspect the area of hazards, make sure that all combustible dust has been removed or isolated from all sparks and heat, and establish safety procedures in the event of a fire.
No one should be allowed to perform ANY type of hot work, including the use of spark-producing power tools, in the vicinity of the dust collector without a permit. However, it happens all the time, and puts lives at risk if the dust is combustible. Take the time to assess this hazard in your own workplace. If the hazard exists, your safety professional should set up hot work procedures to make sure no one puts themselves or the facility at risk.