DSS041: The Five Critical Elements of a Great Dust Hazard Analysis Report with David Hakes

In this episode of the DustSafetyScience Podcast, we talk to David Hakes, President of XP Products LLC in Napierville, Illinois, about the five critical elements of an effective dust hazard analysis report.

Although we’ve covered dust hazard analysis in previous episodes, the subject of report quality has never been fully addressed. If you are a facility manager who has received a report, how do you know if it’s any good? What are the elements that you should be looking for? Is it a set of NFPA standards with a cover stapled on it?

David Hakes has over 30 years of experience in industries handling combustible dust. His company, XP Products, is part of the DustSafetyScience membership directory. The company recently released a three-part video series of dust hazard analysis, so he’s a great person to talk about the five elements of a great dust hazard analysis report.

When NFPA652 originally mandated that all applicable facilities have a DHA done by 2018, David used his background in industrial processes and NFPA guidelines to help his clients in this area. Another deadline is approaching, this one for 2020, so a lot of questions about DHAs are being asked.

In this episode, David talks about the five critical elements of a great dust hazard analysis report. They are:

Methodology and scope
Material characterization
Process characterization
Hazard analysis and recommendations
Administrative controls and recommendations

Methodology and Scope

David explained that methodology is important, but there isn’t a specific process that works for everyone. “It’s really a combination of these methodologies,” he said. He then gave an example of one methodology that he uses successfully.

The node-base methodology was derived from a HazOp and process hazard analysis for the chemical industry. It is easier to use when the client has existing P&IDs (process and instrumentation diagrams) or process flow diagrams.

“Let’s say we’ve got a railcar loading system going into a silo,” David explained. “If the client has process flow diagrams and P&IDs that we can use, we will take and develop nodes from the point of pickup at the railcar outlet through the pneumatic conveying system. Typically, there’s a filter separation and then conveying into the bulk silo. So that whole system there, we may break up into three or four different nodes in each one of those nodes.

“Let’s just assume that we’re looking at environments that have oxygen and a combustible dust present,” he continued. “So as we look at each one of these nodes, we are looking for a credible ignition source and we’re looking for a dust concentration level that would support a combustible dust event. That’s really what we do as we go through that node based arrangement.”

One of David’s clients was a furniture manufacturer that had been visited by OSHA. Eight to 10 nodes were needed for the whole DHA, making it fairly straightforward. On the other hand, a food manufacturer that he recently worked with mixed a lot of powders and cake mixes for a larger facility. That one had 180 nodes.

“The DHA report should specifically call out if it’s one specific methodology such as node-based or if it is a combination of a couple of different methodologies,” he said. “So a node based, what if, and checklists are a couple of forms and that should be clearly defined within the report.”

David acknowledged that he didn’t always have existing P&IDs or the PFDs, so it was important to get information from the client. In some cases, he had to diagram these processes himself and include them in the report. Diagrams of those processes can be required in order to carry out the proper evaluation during the DHA.

Material Characterization

The second critical element to a great DHA is material characterization, which is listing materials being handled and then characterizing them in terms of combustible dust parameters such as PMax and rate of pressure rise.

In the food industry, there are products like flour, sugars, and starches whose parameters are well known: their KST values, PMax values, etc. In the furniture handling industry, this material could be anything from particleboard to a hybrid of wood and plastic. Although there is a lot of published information on these materials, David will usually get samples from the client and decide whether this product needs to be tested further or whether the published data is sufficient to make a determination.

“When we get into other industries, like the chemical field or speciality industries like 3D printing, you can have a combination of fine polymer materials mixed with other products,” he said. “Then we have to rely on additional testing for those materials”.

After collecting information like a list of materials, manufacturer names, where the materials come from, and how they’re received, David and his team will do a DHA search. He mentioned a website based in Germany that has a database of industrial powders.

“Then we look at the hybrid mixtures within the facility,” he said. “So if you have a plant with a packaging line or mixing line, a grinding system and some other form of process, and that’s all being tied into a central dust collection systems then you have a hybrid mixture of powders that you need to test and determine what you’re dealing with.”

Process Characterization

Process characterization includes a variety of steps, such as looking at the different nodes, the dust concentration levels that may be present, and the possibility of ignition source control or the possibility of ignition sources in these different parts of the processes.

It requires a site visit and thorough documentation of every part of the process that is handling combustible dust. The inspector then takes that information and closely examines the credible ignition sources for all those areas.

“It’s a big jump, but that’s really what you need to do to have the content in the DHA,” David explained. “If it’s just a report that with nothing but words and a spreadsheet, we’re going to find it hard to get everyone on board to understand.”

When the report recipient is presented with concrete information instead of the abstract generalized safety concepts that are in the NFPA guidelines, they understand what they have to address. If you can get everyone on board, from operations to maintenance, engineering, the safety group, and plant management, the result is a team effort to make the facility safer.

Hazard Analysis and Recommendations

David said that a lot of clients will immediately ask what their worst case hazards are. In other words, what do they have to deal with now?

“I don’t necessarily like to take that approach unless it’s a small plant and they have a really eye opening issue that needs to be dealt with,” he said. “We categorize the recommendations into a serious hazard and then we’ll call it medium and low.”

He provided the example of a food manufacturer making plant-based products. They had a series of wet dust collectors and dry dust collection systems throughout their plant. After the report was completed, David found that the area with the highest risk was where the various powders were dumped into the mixer.

Bulk ingredients were being dumped into the large dough mixer, generating a lot of dust. Some of it was exposed dust cloud and some of it was contained within the enclosure of the mixer. The dust control they had in place was an existing wet scrubber type system, which drew air into a spray bath and then tried to discharge that air outside and knocking all the dust out of the line. But dust concentration was gumming up the whole wet collector system, so they disconnected it and there was an excess amount of dust.

“So a recommendation in that specific instance was running some calculations on how much airflow would be required to get that dust down to a level that would be acceptable for that room and pointing them in the direction of a couple of dust collector manufacturers that were local to that plant, who could size that system and install that dust collector outside,” David explained.

In the end, the DHA report needs to have a list of the serious hazards and specifically call out either a mitigation or consistent control strategy. There needs to be enough detail that the client doesn’t need to go to another engineering firm to decipher what’s in that DHA report. They should be able to go to their local area rep for bulk material handling equipment who can start either sizing the equipment or doing suppression system calculations to help mitigate and control that combustible dust risk.

Administrative Controls and Recommendations

One of the areas that David focuses on during DHAs is housekeeping practices. He will go through a plant and see whether dust is on the floor or accumulating on the equipment.

“In some cases, we talk about these unknowns, you know, the levels of dust that are building up above ceiling tiles or false ceilings. That is an area that needs to be looked at and that does get overlooked quite a bit,” he said. “But as we know from previous incidents of explosions and major explosions within the past 15 or 20 years, all those areas have to be looked at.”

Housekeeping is more than just keeping the dust off the floor. It’s on ledges, building columns, building joists and any false ceilings in the plant. David said that if he does a review of the plant, he likes to take a quick look at the housecleaning practices and then update them on where they need to improve.

He added that he is not auditing their programs, although preventative maintenance recommendations go into the final report. “Preventative maintenance could reference filter bag changes on a dust collector or checking bearings on rotating equipment like screw conveyors, bucket elevators, rotary valves, grinding systems. Those are very important areas that create ignition sources for combustible dust hazard awareness.”

He also takes a look at some of the emergency planning response procedures. If there is an event, how do they handle that? How do they deal with a flash fire? Combustible dust? If they have a dust collector, that ruptures during an explosion, how do they deal with that?

David said that when you’re creating a DHA, readability is essential. “Nobody wants to stare at a spreadsheet with a thousand different lines and trying to decipher what’s my low, medium and risk for each node. We have to condense that information and put it into a format that is readable by everyone from the production manager and workers in the plant to the engineering manager, plant manager, and even the director of the Environmental Health and Safety Group. So I want to make that point because we’re seeing a lot of reports that are just copy and paste of NFPA.”

He admitted to being a big fan of using pictures and diagrams. “We’re taking snapshots of P&IDs and PFDs. Then we add our own notations onto that and include that in the DHA and try and make it readable. It’s an important part.”

Conclusion

A clear DHA report provides an overview and recommendations that are easy to understand and digest. Over-protection will lead to under-adoption, so if the solutions are not feasible, they’re not going to be adopted, and if they’re not adopted, then we’re not going to make things safer. And our mission is to make things safer.

It’s a fine balance. Experts like David are making inroads and doing that education and really have the experience to show the facilities what they need to do to be safer. The first step in a positive direction is a DHA that works.

If you would like to discuss further, leave your thoughts in the comments section below. You can also reach David Hakes directly:
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/david-hakes-21a336134/
Tel: 630-464-3800

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.