Dust Hazard Analyses (DHAs) for New and Modified Processes

Most facilities that are handling/producing combustible dusts are now familiar with the term “Dust Hazard Analysis” or “DHA” and understand that it comes from a standard issued by the National Fire Protection Association (NFPA), nfpa.org. Furthermore, by now, many facilities subject to the requirements for conducting a DHA on their existing processes have had that completed. The most referred to standard is NFPA 652 – Standard on the Fundamentals of Combustible Dust. This set the requirement to have the DHA completed for existing processes by September 7, 2020. Now the commodity specific standard for agricultural and food: NFPA 61 – Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities did set a different date of January 1, 2022. This is the only commodity specific standard that did this; all other standards refer to the date in NFPA 652. There are a few other differences around the DHA requirements between NFPA 61 and 652. For the purposes of this article, we will just focus on the requirements in NFPA 652.

From NFPA 652 – Standard on the Fundamentals of Combustible Dust, 2019 Edition, these are the key requirements of the DHA:

  • Existing facilities must complete DHAs for all processes by September 7, 2020;
  • DHAs must be performed or led by a qualified person;
  • DHAs must be reviewed and updated every 5 years;
  • For new processes or processes undergoing modification, a DHA must be done as part of the project.

From our experience in conducting DHAs since the first issuance of NFPA 652 in 2015, many facilities are aware of the requirements of the first three bullets above, but what many do not consider or are unaware of is the fourth bullet – completing a DHA for new processes or those undergoing modification. If a new facility is being constructed, your existing facility is adding a new process, or if you are upgrading or replacing your existing process, then a DHA needs to be conducted as part of the project.

So, we know we need a DHA for existing processes and for new and modified processes. Let us take a step back and ask: “Who is enforcing this?” While NFPA creates these standards, they have no enforcement power of their own. Authorities having jurisdiction, or AHJs, are the ones responsible for enforcing the standards. There can be multiple AHJs that are applicable to your facility and/or project. The Occupational Safety and Health Administration (OSHA) would be considered an AHJ and they do utilize the NFPA standards for enforcement; however, that would typically be for existing facilities and/or processes. For new construction or modifications, the two most common AHJs will be:

  • Insurance Companies
  • State & Local Fire Marshal / Building Code Enforcement

Insurance companies are a big driver for completing DHAs on both new and existing. Many insurance companies require completed DHAs to either continue coverage or could require higher premiums.

While the State and/or Local Fire Marshal or Building Code Enforcement are not currently enforcing DHAs for existing processes, many are now starting to require DHAs for new processes to obtain the construction and/or occupancy permits. This will vary by municipality based on the building codes, but we expect to see more and more municipalities require DHAs for new projects.

Whether or not there is an AHJ requiring a DHA for your new or modified process, there is a benefit to having a DHA prepared during the design phase of the project for multiple reasons:

  • It will ensure proposed equipment is adequately protected and in compliance with the applicable NFPA standard(s). For example, if proposed equipment is not equipped with necessary explosion protection, this is cheaper to address during the design phase than after it has been constructed and put into operation.
  • It will ensure the building and/or room(s) housing the new process and equipment is constructed with the correct classifications.
    • Class/Division Rating: Is this a Class II, Division 1 or Division 2 location or is this an unclassified location?
    • Occupancy Rating: Is this a Group F – Factory and Industrial Occupancy or is this a Group H – High Hazard Occupancy?
  • Standard Operating Procedures (SOPs) and Preventative Maintenance (PM) as it pertains to explosive atmospheres or ignition source control can be developed early to ensure proper implementation at commissioning/startup.

It is clear that there is a benefit for completing the DHA for a new or modified process, but how can we do a DHA for something that doesn’t exist yet? At CTI, we do what is called a “Design” or “Desktop” DHA. The steps to this type of DHA are relatively the same as a traditional DHA; however, there is often no on-site component. The DHA is completed based on design documents, process flow diagrams (PFDs), process & instrumentation diagrams (P&IDs), as well as meetings with the various teams involved in the project. This will allow for the completion of a DHA based on how the process is designed to operate.

Once the DHA is completed, you will want to review the findings and recommendations with the project team and ensure any design changes are incorporated to the appropriate contractors and vendors. If there are design changes made to the process after the DHA is completed, the DHA should be reviewed to verify if these changes would require an update to the DHA. Finally, once the project is completed and commissioned, the DHA should be validated to ensure the as-built matches the design and issue a final DHA.

CTI has decades of experience in identifying and reducing hazards from combustible dust and in completing DHAs for new and existing processes. CTI is a principal member of both the NFPA 61 Technical Committee for Agricultural Dust and the NFPA 664 Technical Committee for Wood and Cellulosic Materials Processing and has worked with several of the other committees. We offer the following, and many more, consulting services for dust:

  • Dust Hazard Analysis
  • Hazardous (Classified) Location Determination
  • NFPA and OSHA Compliance Review
  • Explosion Protection Design and Selection
  • Dust Sampling Plan and Execution

Please feel free and contact us to discuss the above-mentioned services or if you have any questions regarding the dust hazard present at your facility.

Leave a Reply

Your email address will not be published.