Is an ounce of prevention really more effective than a pound of cure? According to the U.S. Occupational Safety and Health Administration (OSHA), that’s certainly the case for Arboris®, LLC, a food additive manufacturing facility in Newark, Ohio. A 900-gallon melt tank at the facility containing hexane and ethanol overpressurized and exploded in December 2015. The resulting fireball injured four workers, including two contractors.
An OSHA investigation of the incident resulted in allegations that the employer’s process safety management (PSM) program was woefully incomplete. Arboris had completed some aspects of PSM required by OSHA, but its program had significant gaps—and in those gaps were the makings of disaster. Take a close look at your own PSM program, and make sure you haven’t missed any of these preventive measures.
Complete Your Process Safety Information
Arboris was cited for multiple violations of 29 CFR 1910.119(d), which requires employers to develop complete process safety information for use in the development of safety practices and procedures. Arboris allegedly did not have complete information for its process with respect to:
- The maximum intended inventory. There was no record of how much inventory the system could handle.
- Safe upper and lower limits for temperature, pressures, flows and compositions. Without a maximum intended inventory, there was no way to adequately determine this information.
- An evaluation of the consequences of deviations from safe limits in the process. If you haven’t determined what the limits are, it’s impossible to determine what deviations might do.
- Accurate piping and instrumentation diagrams (P&ID). According to the existing P&ID, the relief piping on the tank that exploded vented to the ground, when, in fact, it did not.
- Its relief system design and design basis. There should be some evaluation of how the relief system is supposed to work.
- Design codes and standards employed. What information was used in developing the system design? The information the employer had in this case did not match the system as designed.
- Safety systems. There was no information in the employer’s process safety documentation about foam suppression systems, flame arrestors, interlocks, level indicators, or lower explosive limit (LEL) meters.
- Recognized and generally accepted good engineering practices (RAGAGEP). OSHA alleges that Arboris failed to document that nine different components of the process were installed in accordance with good engineering practices.
Without complete process information, Arboris lacked what it needed to ensure that the process was properly designed and operating within safe limits.
Action item: Is your process safety information complete and current?
Complete Your Process Hazard Analysis
Arboris was also cited for multiple violations of 29 CFR 1910.119(e) requiring employers to perform a process hazard analysis (PHA), which must be periodically updated. Arboris had performed a PHA, but it was incomplete. The PHA allegedly failed to:
- Identify all potential worst-case scenarios that could lead to an overpressurization of its process.
- Identify the potential for the hexane solvent wash to rapidly boil under upset conditions.
- Identify the potential hazards of material build-up in the relief pipe.
Arboris also allegedly failed to analyze and characterize the hazards created by facility siting in both its initial PHA and follow-up PHAs. Neither PHA addressed facility siting at all. A complete PHA of facility siting should examine the hazards of location, unit layout, storage/warehouses, spacing between process components, control rooms, occupied buildings, unit location relative to surroundings, emergency stations, contingency planning, electrical classification, ventilation, location of emergency relief venting, and evacuation routes through perimeter fencing surrounding the covered process.
Of course, when your PHA is finished, you must arrange to address any items of concern that have been identified. Arboris allegedly also failed to do this; it had no system to promptly address its PHA findings and recommendations, assure that they would be addressed in a timely manner, and document those actions.
Action items: Does your PHA cover all possible worst-case scenarios and dangerous chemical reactions, as well as the hazards inherent in your location and layout? Have you addressed your findings? Have you communicated the findings and your corrective measures to process operators?
Develop Safe Operating Procedures
This is the point where the rubber met the road at the Arboris plant. There does seem to have been a written set of operating procedures in place, but workers were not following it when they added hexane wash to the melt tank—the event that led directly to the explosion.
The workers may not have been following the procedures because the procedures themselves were incomplete, failing to cover all possible situations in violation of 29 CFR 1910.119(f). Specifically, the written procedures did not cover:
- Temporary operations.
- Startup following a turnaround or emergency shutdown.
- Consequences of deviation. In this case, OSHA noted that the procedures did not cover the consequences of adding hexane to the process before it reached the optimal temperature.
- Steps required to correct or avoid deviation.
- Safety systems and their function.
- Special situations, such as lockout/tagout, confined space entry, pipe breaking/line breaking operations, and the presence of workers not directly involved in the operation in the work area.
- Annual review of the operating procedures.
Action items: Do your operating procedures cover all operating conditions, not just “normal production”? Do they give operators the information they will need to correct problems that might arise before they lead to disaster?
Manage Any Changes
Any time you make changes to a covered process other than to replace existing parts or ingredients with essentially similar ones, you must examine the changes from all angles in order to make sure that the process will remain safe. On the day of the fire, Arboris workers used a different chemical in their process—isohexane, rather than the designed n-hexane—but it appears that no one stopped to ask whether the change was safe.
Action item: Ensure that you have written management-of-change procedures, and that operators understand that any changes to the process must be managed using those procedures.
Tomorrow, we’ll look at six more gaps that OSHA identified in Arboris’ PSM program that could have helped to prevent the fire.