Metal Dust Explosion in West Virginia

An explosion occurred on December 9, 2010, at the New Cumberland A.L. Solutions titanium facility in West Virginia when zirconium dust ignited, fatally injuring three workers and causing significant property damage. Inspections by multiple regulatory bodies found that many factors contributed to the incident.

According to the EPA, A.L. Solutions had failed to conduct and implement a Process Hazard Analysis (PHA) at their facilities. By doing so, the company would have uncovered the need for adequate training, management of change in process procedures, incident investigations, audits, preventive maintenance, emergency response planning, and known how to prevent dust explosions.

How the Incident Began

A.L. Solutions processed scrap titanium and zirconium by milling it for several hours, using a blade to reduce the particle size of the material and remove the oxidation on the surface. After milling, operators would blend the metal powder to achieve a uniform composition. Then, the material would be pressed into 3-inch compacts, packaged, and sent to customers. The company was aware of the combustion hazard posed by metal dust so the material was milled and blended in water to reduce the risk of combustion. The blend tank exploded at approximately 1:20 PM on the day of the event during normal operations, killing two operators working nearby. The resulting fires severely burned a third operator who died three days later from his injuries.

Incident Investigation

The U.S. Chemical Safety and Hazard Investigation Board (CSB) determined the ignition source was most likely sparks caused by the blade of the blender scraping on the wall of the vessel. Lead Investigator Johnnie Banks explained, “As a result, the blender was producing heat or sparks due to metal-to-metal contact.” The blender had a metal cover meant to prevent metal particles from dispersing, but the cover was frequently left open during operations. Employees routinely disregarded protocols designed to minimize the amount of combustible material in the mixing area. Before the explosion, the blade scraping the blending vessel's wall was identified as a source of concern, but it was not recognized as a possible ignition source, and no long-term solution was ever implemented.

Although most employees were aware that metal dust was flammable, management had failed to enforce many compliance standards for the safe handling of titanium and zirconium in the workplace. Another factor that greatly contributed to the occurrence and severity of the explosion was the lack of training on safety hazards. Even though workers and management were aware the metal dust was combustible, they did not recognize the importance of following procedures designed to mitigate the hazard.

Lessons Learned

Process Hazard Analysis (PHA)

Recognizing the hazards posed by combustible dust and other potential hazards is crucial for maintaining a safe working environment. Under the OHSA Process Safety Management Standard (29 CFR 1910.119) a Process Hazard Analysis (PHA) is mandatory, unfortunately, A.L. Solutions neglected to perform even one PHA. There are specific factors that a PHA must address to ensure quality and completeness. Gathering all the process safety information (PSI), ensuring the scope does not leave out critical equipment, and choosing the right methodology for your industry such as What-If or Hazard and Operability (HAZOP), are part of the process. For example, A.L. Solutions did not mitigate the hazards of metal dust explosions through engineering controls such as a dust collection system, considered critical equipment. They did not adhere to the practices recommended in NFPA 484 for controlling combustible dust hazards.

An effective PHA leader must be an expert in the methodology used, have formal training, and have solid process experience in either design or operations. If the recommendations that result from the PHA are ineffective, all of the effort expended in updating PSI and applying the methodology could be lost. Therefore, its important to develop an accurate risk matrix so that limited resources can be targeted to those high-risk scenarios that are most urgent.

Compliance regulations require an employer to establish a system to promptly address the team’s findings and recommendations, ensure that the recommendations are resolved promptly, and that the resolutions are documented. This is a key step. For example, it is common practice to list a recommendation as complete because a work order was written, but never verifying the work order was ever completed. Too often recommendations are either not implemented or not implemented as intended by the PHA team.

Dust Explosibility Tests

Zirconium and titanium samples taken from the facility were found to be combustible and capable of igniting when lofted close to heat or an ignition source, according to testing done after the event.

We recommend Explosion severity (KSt), Minimum ignition energy (MIE), Minimum auto-ignition temperature (MAIT), and Minimum explosible concentration (MEC) for facilities that fall under NFPA 652 compliance requirements. ioKinetic's 4-pack of explosibility tests has been designed to provide the basic dust characterization information needed to conduct a successful hazard analysis.

There are many examples of materials that are seemingly harmless on a large scale but can be explosible in the form of a dust. Explosibility screening or testing can determine if a given material is explosible in the form it is being handled.

Management of Change

According to the CSB, “Like all fires, a dust fire occurs when fuel (the combustible dust) is exposed to energy (an ignition source) in the presence of oxygen (typically from air).” If the blender repair had been properly attended to, there would not have been an ignition source. In the days preceding the explosion, staff members had seen the blender having mechanical issues. Several temporary actions were taken to address the problems and continued up to two hours prior to the explosion.

Effective mechanical integrity procedures are a major challenge – especially for smaller companies. Without a proper workflow in place, it is not unusual to lose track of a temporary repair. Part of a compliant Process Safety Management program is documenting the actions taken and tracking deficiency resolutions. An electronic process safety management system is a wise investment to help prevent vital repairs from being overlooked.

Process Safety Training

Proper training at A.L. Solutions would have enabled workers to recognize a possible ignition source in the facility and prioritize its mitigation. Following proper procedures would also have reduced the amount of combustible material present at the facility, in turn reducing the severity of the incident. When it comes to averting and containing fires and explosions, employees are the first line of defense. People who are closest to the source of the hazard can play a key role in identifying dangerous situations, taking preventative action, and/or notifying management if they are taught to recognize and avoid dangers related to flammable dust.

Identifying, managing, and developing employee competencies is a critical component of process safety. Read this article, Competency-Based Learning is the Foundation of Process Safety, on creating a safer future for your organization with training.

We Can Help

ioKinetic has reduced process safety risk, maintained compliance and substantially increased peace of mind for our clients worldwide. To learn more about how we can help you manage risk, contact us today or call us at 1-844-ioKinetic.