Industrial Insurance to Mitigate Combustible Dust Risk

Combustible dust is a known issue for many industries, including in the food, plastics, wood, metal, pharmaceutical, and other processing sectors that must deal with dry  powders that can generate particles that pose a fire or explosion hazard, particularly in the large quantities typically dealt with in the process industries that we all rely on as consumers. In fact, these combustible dust hazards result in incidents each year that impact companies, workers, and communities.

The data is telling — in 2022, the United States experienced 26 explosion incidents. On average in the last eight years of incidents (2016-2023), the US averaged 28.5 explosions each year with at least one fatality related to these events and double-digit injuries each year. Collected by Dust Safety Science (DSS), the data points to a continued need for combustible dust awareness. Along with compiling valuable explosion incident data from around the world, DSS an online resource that compiles a Combustible Dust Incident Database, publishes a related newsletter, annual incident reports, and manages the Dust Safety Professionals Network along with recording a podcast focused on combustible dust safety featuring various industry experts and voices.

Combustible dust — a known risk

Fires and flash fires are a serious issue with combustible dust hazards, but the risk to a company and its personnel in the event of an explosion or secondary explosions can not be understated. As many are aware, combustible dusts can serve as the fuel for an explosion, which requires a total of five elements: First oxygen, an ignition source, and fuel (combustible dust) along with dispersion of the dust in the air and finally for these first four elements to be confined in an enclosure. Note that by “enclosure” this requirement could be met by the process equipment being housed inside a facility. When these five elements combine, the result can be an explosion that potentially could trigger one or more secondary explosions. You can see the escalation from the three elements required for a fire to a flash fire to an explosion in the explosion pentagon shown in Figure 1.

Explosion incidents can mean a serious impact to business, from loss of property to production downtime to worker injury and death. The everyday functioning of companies relies on the application of appropriate safeguards in the form of fire and explosion protection and the implementation of safety protocols to address an incident swiftly. Investigations of past incidents have shown that companies lacking the knowledge to address combustible dust are at greater risk of negative consequences in the form of fines, damages to property and company reputation, and serious risk to personnel.

Understanding Your Hazards

One required and essential tool to understanding the full fire and explosion hazards posed by combustible dust in a facility is the Dust Hazard Analysis (DHA). The DHA is now a requirement for most industries to meet the demands of regulators and insurers. In fact, DHA requirements apply to all new process and facilities that handle, generate, or store combustible particulates (dust), and that the DHA be updated on a 5-year basis to ensure process changes do not create gaps in process safety.

The starting point for a DHA is determining if you have a combustible dust, which requires material (dust) testing, especially processes that deal with finely divided particles. Dust testing can reveal your particular risks by analyzing the dust’s characteristic throughout the process line. For example, a milling operation will have particle size differences as material reduces in size during processing, so two material samples may be necessary. Other operations may rely on mechanical conveying using a belt with moving parts that could generate ignition of nearby or airborne materials, so it’s important to employ a professional that understands the many scenarios in relation to a material’s particular combustibility risks when completing dust testing as part of an overall DHA process.

Code enforcement agencies and authorities having jurisdiction may request a DHA to ensure compliance, but many insurers will also require that a DHA be completed and up-to-date to maintain appropriate coverage. In fact, insurers can inspect your facility and demand a higher premium or drop coverage altogether if appropriate safeguards and documentation is not in place.

Hazard management and risk reduction

When considering what to do for hazard management, it is important to understand what regulators and insurers will be looking for at your facility. Four risk reduction strategies are housekeeping, ignition control, explosion protection, and insurance coverage.

1. Housekeeping

Keeping up with fugitive dust can be a constant battle, but is an important part of facility maintenance and reducing the risk of a secondary explosion. Containing process generated dusts within equipment, for example attaching dust collection to a mill plenum or enclosing the material conveying process using a pneumatic conveying pipeline can keep dust contained and limit explosion risk to those specific and known locations. When this type of equipment is malfunctioning dust can escape and potentially disperse in the air or gather on surfaces. Both these situations can contribute to one or more secondary explosions, which investigations show as often more damaging than an initial explosion incident.

If dust escapes or is building up on surfacing, regular cleaning protocols to remove accumulations from production areas (including overhead areas and less-accessible areas) should be implemented and stringently followed if your dust is combustible. Appropriate cleaning equipment, such as a vacuum system with the proper hazardous duty electrical classification, should be used if needed along with traditional sweeping and mopping if safe for your facility. Remember that using compressed air for cleaning off surfaces could disperse dust in the air, so this method is often not recommended.

2. Ignition control

Determining ignition sources around combustible dust is required because as noted in the explosion pentagon figure, the other elements needed to form an explosion are often constantly present in processing facilities. If ignition sources aren’t controlled, a process upset that releases dust could quickly cause a fire or explosion. Note the following ignition sources:

✅Smoking

✅Hot work

✅Impact sparks

✅Hot surfaces

✅Electrical equipment

✅Static electricity

✅Friction sparks

✅Material self-heating

3. Explosion protection

Explosion protection can come in various forms to suit a particular process, the broad categories of protection include explosion venting, explosion suppression, and explosion isolation. When choosing explosion protection, it is important to note that industrial insurers have created test certification processes and design criteria unique to explosion protection solutions.

For example, FM Approved products have undergone a certification process that requires specific testing limitations for devices to meet. These testing parameters often address known regulatory gaps, which regulators have not yet been able to correct and that could negatively impact process safety. Oftentimes third-party approvals are critical to determine whether the solutions being implemented in your facility are safe and reliable.

Explosion venting to control flame and pressure.

Explosion venting can be installed on vessels to direct the pressure and flame from an explosion event in a planned pathway that protects people, equipment, and plant areas sensitive to the by-products of an explosion. A typical vent will be located on outdoor equipment that can safely point the flames, smoke, and pressure out and away from equipment and interior, confined areas where secondary explosions are a risk.

Vents are attached to a vessel, for example a silo or a dust collector’s housing, and if an ignition occurs and results in an explosion the flame and pressure follows the path of least resistance out the explosion vent. Vent accessories like blast deflectors can work in concert with an explosion vent by limiting how the vent angles open during a deflagration or explosion and deflecting the flame ball and other material upward and outward from the protected vessel.

Another type of explosion vent is the flameless vent. A flameless vent incorporates an explosion vent that's installed on a vessel along with unattached stainless steel mesh in different shapes to provide different flameless venting area for challenging applications, particularly for indoor explosion protection on vessels. The flameless vent works by quenching the flame as it's exhausted into the flame arrester or steel mesh, effectively managing the flame exhaust from the explosion while still relieving the pressure from the explosion. The flameless vent can be used indoors or out and helps to limit the effects from a deflagration to the immediate area around the protected vessel.

The flameless vent works by first directing the flame and pressure from an explosion through an explosion vent that then offers passive protection by forcing the flaming pressure into layers of stainless steel mesh that effectively extinguish the flame and offer a torturous path to trap and stop flame and other by-products from escaping into nearby plant areas and impacting workers. The flameless vent also acts as a vacuum breaker to allow outside cool air to enter the vessel and safely achieve equilibrium.

Explosion suppression for high-speed, economical deflagration management.

Explosion suppression systems use pressurized bottles containing a dry suppressant that responds to a detected explosion or deflagration by releasing a high-pressure suppressant into a vessel or pipeline at the earliest stages of an incident. The suppressant meets the pressure and flame from an event and quickly extinguishes and stops the deflagration from spreading to other areas or vessels. The biggest drawback to this versatile system is that bottles must be serviced after activation and the suppressant can contaminate materials being used in the process at the time of a fire or explosion event.

Suppression systems require a controller, which accepts a signal from either a pressure or optical detector placed near the suppressant bottles. Once a flame or pressure rise is detected, a signal is sent to the controller, which in turn sends an activation signal to the bottles to release the suppressant into the area to stop further development of the deflagration. The controller offers an option to monitor multiple suppression bottles to protect entire process areas. System’s benefits can include a long service life (if not activated), telescopic nozzle options, process pressure monitoring, OSHA lock-out capabilities, and a replaceable design.

Explosion isolation to stop deflagrations from spreading.

Explosion isolation reacts quickly to a propagating flame front and stops the flame and pressure from strengthening and reaching different parts of interconnected processes.

Isolation of process equipment is typically a physical barrier that “shuts off” access through a pipeline connection, whether using a metal flap or gate, an inflatable bladder, a disc that slams shut from pressure, or a suppressant release from a bottle system, or a mesh cartridge insert installed on a clean air pipeline that stops deflagrations using flameless venting principles.

The choice of isolation method is typically application dependent and can rely on detectors in the pipeline for activation (slide gate valve, pinch valve, suppressant bottle) or be a passive solution such as a flap valve or mesh cartridge-style quench valve. Understanding a combustible dust’s Kst, sanitary requirements, abrasiveness, toxicity, and other characteristics can help to determine which solution will protect your process and interconnected systems.

4. Insurance coverage

Insurance coverage helps companies reduce their overall risk exposure and can provide education and guidance for companies that need to ensure they have adequate safeguards in place to prevent a catastrophic incident. Insurers will pool risk and offer payment to help with rebuilding damaged plant areas, worker medical bills, and equipment replacement and repair to reduce process downtime. Many large-scale industrial insurers like FM Global offer very specific combustible dust guidance, including in the FM Property Loss Prevention Data Sheet 7-76 “Prevention and Mitigation of Combustible Dust Explosion and Fire,” which offers recommendations to reduce the frequency and severity of combustible dust explosions.

Insurers have extensive experience with combustible dust explosions and the related damages they cause, so have taken a prescriptive approach to ensure that the companies they choose to insure are following or exceeding industry best practices. By offering proven engineering guidelines for high-risk processes, they can better serve clients before an incident occurs by sharing valuable and specific loss prevention advice.

Accepting responsibility around combustible dust

Combining the experience and guidance of insurers familiar with the true costs of a combustible dust incident along with regulatory standards from the National Fire Protection Association (NFPA), which has been adopted by the Occupational Safety and Health Administration (OSHA) as enforceable safety regulations, is a solid pathway toward a safer workplace for companies dealing with combustible dust. However, many challenges remain when it comes to combustible dust hazards.

🎓Education and training. Incredible progress has been made in educating manufacturers about the hazards involved with combustible dust. In North America, we now have the Advanced Manufacturing and Bulk Solids Technology Center, which is part of Kansas State University. This center is the only one in the country that specializes in powder and bulk solids materials testing, education, and research to help educate students and professionals. While many courses focus on other topics, safety and material testing are a central focuses for some course offerings and research efforts at the center.

In addition, there are also courses organized for engineers through trade groups, non-profits, colleges, and industry-centered publications that can provide training and accredited courses on the subject of combustible dust safety and addressing prevention and mitigation strategies. Many explosion protection companies are also able to offer personalized company trainings to address the specific safety requirements for an individual facility or process line.

📄Proper DHA compliance. Finding a qualified, experienced consultant or third-party expert to help properly complete a DHA remains a challenge. DHAs have only been required since 2018. In contrast industrial safety consultants have previously focused on the completion of Process Hazard Analyses (PHAs), which differ from the DHA and have been conducted since the 1990s to analyze hazards in companies that deal with toxic and reactive chemicals. The PHA has served to promote process safety for chemicals, but after having incidents in the 2000s involving nontoxic materials like sugar being the fuel for large industrial accidents, regulators and industry groups have pushed for a similar hazard analysis method focused on combustible dusts.  

Finding experienced professionals that understand the risks specific to these hazards can be challenging as industry awareness of the new requirements continues to grow and more companies complete and renew their DHAs. While North American companies are now expected to complete DHAs, other emerging economies in South America, Asia, and elsewhere are still deciding on industry regulations around combustible dust, which means that standards, regulations, and best practices are constantly evolving to meet new safety challenges. In addition, long-established safety requirements in Europe, such as ATEX, also influence companies in North America, particularly global corporations with overarching safety goals, including those related to combustible dust hazards.

✔️Certified, third-party tested explosion protection. Industrial explosion protection is similar to many other sectors. Some suppliers have engineered explosion vents, isolation equipment, and suppression systems to meet minimum standards to protect applications. To meet the highest industry standards and to protect the broadest and most challenging applications, many high-quality explosion protection companies have sought out third-party testing and certification.

These efforts ensure that products like flameless vents can be installed with confidence even when handling challenging materials like highly explosive metal dusts or abrasive materials that quickly wear through untested isolation devices. This testing is also important to identify the most economical explosion prevention and mitigation solutions, so the most practical solution for a given process is clear. Not only will this best serve a budget and process, it will also reduce replacement costs associated with unneeded safety solutions in the event of an explosion incident.

Sharing knowledge and relying on experts can reduce risk

Whether your company has a stellar safety record or has experienced an explosion incident, it is a shared responsibility to keep workers safe. Insurance providers are another resource to explore because they have a vested interest in preventing safety lapses that result in various negative consequences from the devastating potential for worker injury or death to production downtime to litigation to irreparable damage to your company’s reputation.

Not only do insurers provide support when it comes to reducing and mitigating financial risk, they can also be an important tool in discovering how to approach combustible dust risk from companies with decades of experience handling the tangible impacts that an incident can have on a company’s operations. Remember to consider how risk plays into operations and choose proven risk reduction strategies from the experts.