NFPA 484 2015 EDITION – STANDARD FOR COMBUSTIBLE METALS REVISIONS AND THE ABRASIVE BLASTING INDUSTRY
AN IMPORTANT AND LONG OVER DUE REVISION TO THE 2015 EDITION OF THE STANDARD IS THE INCLUSION OF MEDIA BLASTING AS A PROCESS LISTED IN EACH INDIVIDUAL METAL CHAPTER 12.7,13.7, 14.7, ETC;
MACHINING, FABRICATION, AND MEDIA BLASTING
Abrasive (media) blasting is a process that does in fact generate dust and in many applications, a combustible metal dust. However, until the 2015 edition of NFPA 484 abrasive blasting hasn’t been included or listed as a process within the standard. Since, abrasive blasting has been omitted as a process, the abrasive blasting industry as a whole has been able to look the other way regarding the combustible dusts often generated by abrasive blasting.
The abrasive blasting industry has a handful of sales professionals, engineers, equipment and media manufacturers who are knowledgeable and conscientious about their approach to combustible metal dusts generated during the blasting process. However the industry, in general, isn’t particularly knowledgeable about combustible metal dusts, the dangers of combustible metal dusts or how best to handle combustible metal dusts generated during abrasive blasting.
It can be safely stated, that many within the industry have never heard of NFPA 484 much less know which metals are considered combustible.
This general lack of awareness and knowledge has created an industry that unknowingly neglects addressing combustible metal dusts generated by the equipment and abrasive media they sell. It is extremely common for manufacturing facilities to use abrasive blasting equipment as part of their manufacturing process. How many owners, equipment operators, plant and production managers, HS&E personnel and departments are aware of the combustible metal dust generated during the abrasive blasting process when the salesman & technicians selling or servicing the equipment don’t know to mention this rarely addressed topic?
Most sales professionals in the abrasive blasting industry have customers who’ve experienced equipment and collector fires. Especially susceptible to combustible metal dust fires are applications utilizing centrifugal wheel blast equipment. Wheel blast equipment typically uses a metallic media to blast metal parts. Often, the media used is cast steel shot or grit and although parts can vary greatly in their material composition, aluminum is a very popular metal blasted using wheel blast equipment. Magnesium and titanium are also popular metals blasted by centrifugal wheel blast equipment.
Let’s go one step further; the combination of the metal removed from the part being blasted and the subsequent breakdown of the metallic media used creates a mixed metal within the blast chamber and dust collector.
NFPA 484 strictly prohibits the mixing of certain metals.
In addition to cast steel shot and grit used as an abrasive blasting media, other metallic abrasives used for blasting include aluminum, zinc and stainless steel.
One of the challenges faced when incorporating a wet dust collector with abrasive blasting equipment and specifically wheel blast equipment is the size of the dust generated. Dusts smaller than 2 micron (including submicron) will be pulled up and out the top of the wet dust collector. Dust this small isn’t captured efficiently with a wet dust collector alone. However, there are ways of capturing fine dusts such as incorporating a high efficiency cyclone separator or post filtration.
More attention is being given to combustible metal dusts generated during processing and finishing including, but not limited to; sanding, polishing, sawing, grinding, buffing and abrasive blasting. Everyone including owners, equipment operators, plant and production managers, HS&E personnel, maintenance departments, media and equipment manufacturers, consultants and salesmen need to do their due diligence regarding the dusts generated during the manufacturing process. The proper handling and collection of combustible metal dusts is essential in keeping facilities and employees safe from fires and potential explosions.
Each year there are dozens of facility fires involving combustible dust. Many of these fires go unreported. Additionally, many fires are combustible metal dust fires. Every year millions of dollars in equipment and facility damage, injuries and yes, sadly, even fatalities result from combustible dust fires.
Let’s do our part as suppliers, consultants, manufacturers, employees, operators and owners to inform and educate ourselves, and our customers on the proper handling of combustible metal dusts. We just might play a small role in saving someone’s life.