As originally published in CTI’s Compliance Matters Newsletter – Summer 2015. By: Chris Frendahl and Jeff Davis, PE
On September 1, 2015, the National Fire Protection Association (NFPA) issued NFPA 652, Standard on the Fundamentals of Combustible Dust. NFPA 652 is the first step to creating a single, unified combustible dust standard that would apply to all facilities.
A significant number of industrial accidents have been associated with combustible dust flash fires and explosions. Historically, the hazards from combustible dust are often overlooked, in part due to facilities not understanding the hazards of combustible dust. However, there are other cases where the hazards are overlooked due to complacency or a general attitude of “that can’t happen here.” The Occupational Health and Safety Administration (OSHA) worked to increase awareness to the hazards associated with combustible dust through a National Emphasis Program (NEP), reissued March 2008 in direct response to the Imperial Sugar incident near Savannah, GA. OSHA has also released an Advanced Notice of Proposed Rulemaking (ANPR) to create combustible dust regulations. OSHA’s NEP and ANPR both cite NFPA standards for combustible dust. However, NFPA’s combustible dust standards are industry specific. For example, grain handling facilities and food processing plants refer to NFPA 61, while wood processing and woodworking facilities would refer to NFPA 664. Many of the industry specific standards will refer, at least in part, to NFPA 654, the standard for industries without a specific standard. These standards do not align with each other. For example, NFPA 654 has differing dust collector exemptions from NFPA 61, yet NFPA 61 will refer to NFPA 654 for standards on pneumatic conveying lines, which could be associated with dust collectors. This creates confusion. To reduce this confusion and consolidate the combustible dust standards, NFPA has developed NFPA 652, Standard on the Fundamentals of Combustible Dust. In addition to the development of this standard, NFPA has been working to update the industry specific standards to align with NFPA 652.
NFPA 652 applies to “all facilities and operations that manufacture, process, blend, convey, repackage, generate, or handle combustible dusts or combustible particulate solids”. In addition to the general requirements listed in the standard, NFPA 652 will also direct you to any applicable industry-specific standards that would apply to different facilities.
The primary focus of NFPA 652 is to help all facilities identify where hazards exist due to combustible or explosible materials that are handled by the facility. To accomplish this, NFPA 652 requires a qualified person to conduct a Dust Hazard Analysis (DHA). The requirements of the DHA are retroactive and existing facilities will have three years from the issuance of NFPA 652 to complete the DHA. The DHA includes the following:
- Determining the combustibility and explosibility hazards of the materials being handled;
- Identifying and assessing the fire, flash fire, and explosion hazards;
- Managing the identified fire, flash fire, and explosion hazards; and
- Communicating the hazards to affected personnel.
To determine the combustibility and explosibility hazards and identify the areas where the hazards exist, facilities will need to sample and analyze the materials. To do this, all facilities are required to create a sampling plan. This plan must identify where the fine dusts are present, the collection procedures for representative samples, communication with the testing laboratory, documentation of the sampling, and safe sample collection practices.
Once materials have been identified as being combustible or explosible, the facility must then complete a DHA to identify and evaluate the potential hazards associated with a fire or explosion due to the combustible materials being handled. Inspections of areas where combustible dust is handled also allow for the provision of recommendations to minimize the risks of a combustible dust incident. The DHA must be completed or led by a qualified person who has demonstrated the ability to understand combustible dust and associated hazards through education or experience. This qualified person should inspect all buildings and processes to determine how likely it is that a fire or explosion due to combustible dust will occur. This is determined by understanding the properties associated with the combustible dust that is handled in the building or process, identifying all potential ignition sources, and evaluating the effectiveness of any deflagration suppression or protection systems that are currently in place.
Once all hazardous areas have been identified and a DHA has been completed, the facility should work to reduce the risk of a flash fire or explosion from occurring or should implement procedures or equipment to mitigate the hazards associated with a combustible dust fire or explosion. Often times, updated housekeeping procedures are the first actions facilities take to combat excessive dust accumulation in rooms and buildings. However, this requires extra labor and is often not as effective as expected. Additionally, some housekeeping activities, such as cleaning dusty areas with compressed air, can pose significant hazards resulting from combustible dust clouds forming in the areas that are being cleaned. If possible, the facility should work to contain and collect combustible dust by preventing fugitive dust from discharging from equipment and using an effective dust collection system throughout the processes handling combustible dust. However, if it is not feasible to prevent the discharge of fugitive dust into a room or building, other means of protection or hazard mitigation should be implemented. NFPA 652 states that any building or room where a dust deflagration hazard exists should be protected using venting systems that comply with NFPA 68. Also, pneumatic conveyance systems must be equipped with deflagration protection or suppression systems that will prevent a flash fire from traveling throughout the conveyance system and connected equipment in accordance with NFPA 69. Exhaust air from equipment should only be directed outside and not into the room unless specific guidelines are met. Facilities should also ensure that all central vacuum systems are equipped with tools and attachments that are constructed of metal or static dissipative materials and that all vacuum hoses are properly grounded.
The facility should develop a management system that monitors how hazards relating to combustible dust are being controlled. This system must include Management of Change (MOC) procedures to be implemented prior to any proposed changes to materials, equipment, technology, procedures, and job tasks. Finally, NFPA 652 requires facilities to provide training to employees and contractors on general safety regarding the hazards associated with combustible dust as well as any job-specific training relating to their work environment.
If you need assistance developing or implementing a sampling plan, conducting a Dust Hazard Analysis, or providing employee training, please do not hesitate to contact CTI.