This is a response to a client regarding their question… do we need to use non-sparking tools in our flammable and combustible dust areas? This is a GREAT practice, but many people may be surprised that OSHA has to use its GDC to cite this requirement, as it is NOT an OSHA/NFPA/IFC requirement. Of course, we need to control ignition sources in our flammable and combustible dust areas, but when those areas are Division 2 locations, when is this safeguard required? So here is my response (off-the-cuff risk analysis). I thought some of you might find it helpful as well.
PLEASE NOTE:
NMP is very different from Electrolyte due to its FP of 196 and its VP of less than 1 mm HG.
Not only does this email apply to flammable liquids and gases, the same approach should also apply to our COM DUSTS areas, which are Class 2 HAZLOCs.My take on Non-Sparking tools. (Buckle up as this may be a bumpy ride!)
Fact 1: Mechanical spark energy: The kinetic energy of a slipping/dropping wrench can be several joules (e.g., a 0.5-pound tool falling 15′ has ~10 J).
Fact 2: NMP and Electrolytes have an MIE of LESS THAN 1.0 mJ, so a dropped tool or a tool slipping off a bolt/nut has PLENTY of energy to be an ignition source to these flammable vapors should they be in their FLAMMABLE RANGE.
Fact 3: NMP at standard temp and pressure, having a FP of 196°F, is really low risk, and non-sparking tools would not be a necessary safeguard; HOWEVER (and this is BIG however), NMP work around the Distillation Columns/Purification Towers is a VERY DIFFERENT scenario as we have heated the NMP to within 30-degrees of its FP, and any work taking place that OPENS the process in this area should mandate non-sparking tools.
Fact 4: Combustible dusts typically have MIEs of 30.0 mJ and higher. I do NOT know what our combustible dust MIEs are, but after we do our DHA in the coming weeks, this will become clearer. BUT the Com Dust is a different beast we have to tame! Poor housekeeping that allows dust to accumulate to 1/8” and someone drops a regular wrench onto that surface can create a small dust cloud by the topped tool, and if that tool creates enough energy, that will be the initiating event for the second and more destructive dust explosion. Do not think this in regard to dropping the tool on the floor, as I doubt we will have that issue in a clean room. Think about a worker in a lift working 30’ in the room over a beam that never gets clean due to its height. The tool strikes the “dirty beam” and begins the event.
100% required by the ERT who are or may be working in an area where a Loss of Primary Containment event involving a flammable liquid or gas. This is an uncontrolled release environment, and LEL% or FP has no bearing on the risk assessment these responders use in developing their Incident Action Plan. They MUST ALWAYS use non-sparking tools in such an UNCONTROLLED RELEASE environment (i.e., inside the HOT zone). And Quality concerns are the least of our concerns in this situation!
For REGULAR maintenance work on a CLOSED PROCESS, which includes both NMP and both Electolyes are CLOSED PROCESSES by code definition, Non-Sparking tools are NOT necessary since our HAZLOCs are Division 2 areas – NOT Division 1. However, once the process is OPENED, for example, removing a component such as a pump or valve, and we have the potential for a flammable atmosphere, non-sparking tools should be required in that working environment. As we discussed in our Line Break Training, if we had “Positive Means of Isolation” for that opening, the area would be LOW risk, but single valve isolation makes this area HIGH risk, and we need to apply every Administrative Safeguard we can while that flammable/Com Dusts process is OPEN.
We SHOULD mandate that tools used to UNLOAD/LOAD flammable liquid tanker trucks be NON-SPARKING, as the connection points where they are working WILL BECOME an OPEN process, such that the hose connection points are managed as Division 1 locations, per NFPA 497. This is why we wanted Div 1-rated radios to ensure these personnel have the correct rating on their electronic devices while performing this high-risk work. This practice SHOULD be applied to flammable liquid TOTES as well, anywhere on the plant site.
My concern is our lack of “flammable safety” maturity. We don’t have the knowledge base or maturity to safely decide when we need spark-resistant tools and when we can work safely without this safeguard. Therefore, I suggest we require them in areas we have designated as Class 1/2, Div 1/2 HAZLOC. We can always revisit this risk analysis at a later date as we mature in our management of flammable liquids and COM Dust hazards. In my world, SAFETY TUMPS Quality. We have to be aware of QC concerns, but there are other non-sparking tools that we can purchase that will solve the Quality Group’s concerns.
I hope this helps,
Bryan