DSS056: Hazard Identification And Evaluation Through Dust Hazard Analysis With Walter Frank

In this episode of the DustSafetyScience Podcast, we interview Walter Frank, founder of Frank Risk Solutions in Wilmington, Delaware, about hazard identification and evaluation through dust hazard analysis.

Walt has over 45 years of experience in incident investigation and explosion hazard evaluation. As a member of NFPA652 and 654, he has the knowledge and experience to address dust hazard analyses in facilities handling combustible dust. Walt also wrote Chapter 5 in the book [Affiliate] Methods and Chemical Process Safety Vol. 3 on Dust Explosions, which we reviewed in Episode #53 during an interview with Dr. Paul Amyotte and Episode #54 with Ashok Dastidar.

In this interview, Walt answers questions like the following:

What is the purpose of a dust hazard analysis?
How do you evaluate existing safeguards as per the DHA process?
How are the recommendations created?
What are the best practices for DHA documentation?
What are the next steps after completing a DHA for a facility?

What Is The Purpose Of A Dust Hazard Analysis?

Walt explained that dust hazard analyses are intended to identify the following:

What materials are present that pose combustible dust safety concerns
How those concerns might be manifested- what scenarios could lead to a combustible dust fire and explosion?
Any existing or new controls needed to mitigate hazards

The concept of DHAs dates back at least 20 years. Walt, who was on the NFPA 654 committee at the time, recalled that other people on the committee had come from industries that were regulated by the OSHA process safety management (PSM) standard.

“They were dealing with combustible dusts that were not covered by the OSHA PSM regulations,” he explained. “Dust hazard analysis was one of the first concepts that we integrated into NFPA 654 and, over the course of time, the other combustible dust standards followed suit. Now here we are- some form of dust analysis is a requirement in all of the NFPA standards.”

How Do You Evaluate Existing Safeguards As Per The DHA Process?

Safeguards like mechanical or instrumentation systems must be designed and installed to correctly perform its intended function. They must also be regularly maintained and tested, so having a good inspection and preventive maintenance program for mechanical and instrumentation safeguards is important.

Not all safeguards are mechanical or instrumentation-based. Sometimes it involves operator intervention. An alarm sounds and an operator responds. For this type of safeguard, Walt said that he uses the following testing criteria:

Is there something that’s going to signal the need for a response?
Is there a written procedure that tells the operator what to do when that signal or alarm occurs?
Has the operator been trained on the procedure?
Has their understanding of the procedure been evaluated?
Does the operator have time to intervene before the deviation leads to fire or an explosion?
Does the operator have the physical capabilities to do what must be done in the time allowed?

“We’re reliant on safeguards: either human or mechanical or instrumentation,” he explained. “We just have to make sure that we’ve got a sound basis for confidence that those protections will really provide the mitigation that we’re counting on.”

Walt recommended caution in cases where the same box controls multiple pieces of equipment.

“Maybe you have a failure of (a grain dryer) temperature transmitter and that causes the dryer to overheat. If you have an interlock that’s supposed to shut the dryer down at high temperature and that interlock takes the same signal from the same transmitter, then those two devices are not independent of each other. Failure of the transmitter can defeat both systems.”

There must be a common framework to identify the safeguard and the interdependencies and detect any conflict. Walt referred to a technique called LOPA (layer of protection analysis) that provided a more detailed and disciplined assessment of protective features. It answers the following questions:

What happens if this component fails?
What will be the consequences of the failure of this component?

In his chapter, Walt described a technique called failure mode and effects analysis. With a temperature control system, you would analyze the outcome if the transmitter or control valve failed, or if the system showed a false low signal.

He also emphasized the importance of having the right combination of people on the inspection team. Ideally, it will consist of someone with experience in operating the unit, someone with an engineering background who understands the design, and someone who knows how to lead the team.

“The key is having the right expertise and experience on the team so that the deliberations are credible and productive.”

How Are The Recommendations Created?

According to Walt, there are two ways to create safety recommendations after a DHA:

Referring to the relevant industry standards. There are many prescriptive requirements in the NFPA combustible dust standards, so doing a gap assessment of the process and the installation against the requirements of the NFPA standards will help.
Proposing creative solutions. Although detailed, the NFPA standards cannot address every conceivable situation, so there needs to be some creative thinking on the part of the DHA team. If they come up with a scenario and they don’t have a protection against the potential consequences, they need to propose some solutions.

It’s always possible that the DHA team may have to address hazards other than the combustibility of the dust. For example, inerting is often used to prevent fires and explosions, and many inerting gases are asphyxiants. If inerting is a proposed or existing safeguard, the team should review how to safely address the asphyxiation hazard.

Walt stressed the importance of coming up with safeguards that are reliable: in other words, they are feasible to implement. If any safeguard is going to take time to design and install and the situation is high-risk, it is critical to look for interim protection that can be put in place for the short term.

What Are Best Practices For DHA Documentation?

Many NFPA standards require DHA results to be revisited and updated periodically, usually every five years, so a well-documented report is a must for two reasons:

The learnings can be used to improve current safety conditions
The next DHA team can use it for reference and close any gaps that may have been missed

Walt recommended that DHA reports include a short executive summary describing the process, which portions were studied, and who was on the team. The rest of the report would be dedicated to the issues that were addressed, thorough descriptions of all evaluations, and a summary of the recommendations.

What Are The Next Steps After Completing A DHA For A Facility?

When asked to identify the most important step after a DHA, Waly answered, “Making sure you actually implement the recommendations. You spent a lot of time and expense in assessing and analyzing the process. You’ve come up with some recommendations. Those recommendations are intended to improve the safety of the process. Well, if they don’t get implemented then all of that effort, time and effort have been wasted.”

He recommended that responsible individuals be tasked with implementing specific recommendations by a certain due date and that any hazards that will take longer to address should have temporary safeguards put in place. When a recommendation is closed out, it should be inspected.

“Bottom line- it is a terrible tragedy to see somebody injured just because a safeguard that had been identified was overdue for implementation, and that safeguard would have possibly protected that person if it had been put in place on a timely basis.”

Conclusion

When Arpad Veress was interviewed in Episode #20, he mentioned that his company’s motto was that the equipment must be safe and then functional.” It’s a statement that perfectly summarizes the need for regular DHAs and other safety measures in industries handling combustible dust.

If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Walter Frank directly:
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/walt-frank-pe-ccpsc-aa519138/

If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.