Power Engineering International

Don’t let your business go up in smoke

Full disclosure up front is a necessary step toward mitigating or eliminating explosion risks, writes Andrew Parker

It should come as no surprise that fires and explosions cost companies billions of dollars each year.

Lost productivity, the cost of repairing or replacing damaged or destroyed equipment, settling lawsuits originating from employee injuries or deaths – it all contributes to the total.

Industrial operations are particularly familiar with the dangers of explosions, especially those that handle materials such as biomass, wood pellets, sulphur, oil and gas.

Countless incidents that occur within industries that are susceptible to explosions can be mitigated or eliminated entirely in a variety of ways. Perhaps the most effective method of minimizing the risk of explosion involves a simple conversation or consultation at the beginning of the equipment selection process.

It’s true that any reputable equipment manufacturer will know that the potential for explosion exists within all of the aforementioned industries, as well as others. That knowledge will (or should) prompt them to ask certain questions in order to collect the required data for proper equipment selection.

A conveyor manufacturer, for example, will ask if the equipment needs to be gas- or vapour-tight due to the nature of the product being handled. The customer’s answer will determine if the conveyor needs to be inert.

However, those who are responsible for the procurement of equipment in any industrial application must remember that it is their responsibility to inform their suppliers about the material they’re dealing with – and do so in a way that makes it clear they need a plan for mitigating the potential for explosion.

This stresses the importance of establishing a true partnership between customer and supplier, instead of treating the relationship as a simple business transaction. There needs to be a high level of trust and an open exchange of information in order to avoid catastrophic consequences.

Often the most important information regarding the explosive properties of a particular material – or, more accurately, the dust it creates – is revealed through third-party testing, which must be commissioned by the equipment purchaser. This testing will eliminate any guessing or doubt as to any potential dangers that could occur during the material handling process.

Once this information has been obtained and shared with everyone involved in the design and implementation of the equipment, the supplier can pick up the proverbial ball and run with it.

In the case of conveyors, manufacturers are able to plan for several safeguards that can help prevent explosions from occurring in the first place, or at least minimize the damage if they do happen.

Explosion venting is a relatively economical way to account for the potential for explosions. In fact, in the US there are National Fire Protection Association (NFPA) standards in place that mandate the implementation of this safeguard when handling various materials.

In the event of a fire or explosion, vents will blow open beyond a certain psi level to provide relief for the internal pressure caused by the incident. This provides a termination point that contains the damage to the conveyor. Without proper venting, equipment acts as a plenum or chimney and moves the volatility downstream, where a more catastrophic explosion could occur.

Nitrogen purging a conveyor will make it inert by limiting the amount of oxygen within the equipment so it doesn’t react with hydrocarbons and create explosive mixtures.

Adding lifting/grounding lugs to conveyors can mitigate the potential for static electricity to create a spark or start an arc.

Using plastic or synthetic UHMW paddles to move material through the conveyor is another way to reduce the possibility of sparks by eliminating steel-to-steel contact within the equipment.

Sparks are among the most common causes of industrial explosions, and it only takes one to detonate volatile material dust.

Ultimately, none of these options can deliver the necessary benefit without open communication between customer and manufacturer.

Experienced suppliers will understand that handling grain or sulphur automatically goes hand in hand with potential explosion issues, and they will ask if it’s necessary to plan for certain safeguards when manufacturing the customer’s conveyors.

Drag conveyors and bucket elevators, which are typically used in these applications, can be manufactured with a closed design to control dusting. But in most cases, that’s not enough to cover all the bases related to avoiding explosions.

With other materials, the explosion risk isn’t as obvious. That’s when full disclosure about material properties is absolutely essential. Equipment suppliers can only create a solution based on the information they receive from a customer.

If that information is lacking for any reason, an explosion occurs and an inspection by the NFPA reveals that the proper equipment wasn’t installed, insurance won’t cover those losses. A single situation like that could be enough to shut down an operation forever, not to mention the human cost of injury or loss of life.

There are many challenges associated with conveying bulk materials.

At the very top of the list is understanding the properties of those materials and how they interact with each other, as well as how they interact with all of the environmental factors in a given operation.

Equipment is one of those factors, and suppliers all must adhere to a strict set of industry-standard guidelines for fire prevention and explosion mitigation when designing a proposed solution.

But even those guidelines can’t account for everything a conveyor might encounter in a specific application.

When customers provide results from third-party material testing and suppliers offer extensive knowledge about material characteristics and behaviour acquired from years in the field, the likelihood of an explosion is minimized significantly – as is the potential for unimaginable losses.

Andrew Parker is vice-president for CDM Systems, Inc. He has more than 20 years of experience in the bulk material handling industry and overseas operations including conveyor design and development. For more information visit www.cdmsys.com

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