Plants constantly undergo changes, whether due to economics, maintenance of the facility or upgrades to an existing installation. In order to safely implement changes, a facility often has to undergo an extended shutdown. Upon completion of shutdowns, a startup process takes place. In a startup, multiple actions are sometimes required to occur simultaneously to ensure a smooth transition from an energy-isolated state to a fully running, stable operation.
The efficacy of a PSSR depends on verification of every single item in the checklist, regardless of perceived importance.
Recognizing how complex a startup process can be, OSHA Code of Federal Regulations (CFR) §1910.119 (i) requires that a systematic and thorough check of the process be completed prior to the introduction of a highly hazardous chemical. This Pre-
Reinaldo Kusliawan, Lead Consultant, Smith & Burgess
Startup Safety Review (PSSR) must confirm the following:
- Construction and equipment are in accordance with design specifications.
- Safety, operating, maintenance and emergency procedures are in place and adequate.
- A process hazard analysis has been performed for new facilities, recommendations have been resolved or implemented before startup, and modified facilities meet the management of change requirements.
- Training of each employee involved in operating a process has been completed.
Ultimately, the purpose of a PSSR is to minimize the probability of overlooking any important safety aspect during a startup. When performing a PSSR, it is not an overstatement to say "The devil is in the details." An oversight of any details can lead to a catastrophic consequence. Such was the case when an incident occurred at the Bayer CropScience West Virginia plant in 2008. A runaway chemical reaction occurred inside a methomyl unit residue treater vessel, causing an explosion. Two fatalities and multiple injuries were recorded.
Prior to the startup, the methomyl unit had undergone an upgrade of a control system and a replacement of the residue treater vessel. An investigation by the Chemical Safety Board concluded that one of the contributing factors to the runaway reaction and loss of containment of flammable and toxic chemicals was the presence of multiple gaps in the PSSR.
Among the errors identified were the failure to update an existing operating procedure to address changes pertaining to the control system upgrade and failure to verify that all equipment had been installed and configured as the design intended before introducing the chemicals in startup. In this case, the PSSR failed to capture the installation of valves, which contributed to the overconcentration of methomyl in upstream "flasher" equipment. Upon the residue treater's startup, a minimum operating temperature interlock, which prevents the addition of methomyl into the system, was also bypassed due to past startup experience. The combination of the errors eventually resulted in the explosion of the newly installed residue treater.
What could have been done differently to prevent the incident? According to the staff interviews, the PSSR did not directly involve operators or other subject matter specialists. Although the PSSR checklist indicated that all the steps were completed as intended, there was no follow-up to verify the completion of those items. Failure to perform this verification was a direct violation of the PSSR requirement as mandated in OSHA CFR 1910.119. Had an authorized person verified each item in the PSSR checklist, the deficiencies in the installation would have been identified, intervention prior to startup could have occurred, and the consequences of the event may have been prevented. The important lesson to learn is any weak link in a PSSR, no matter how trivial, could render the entire PSSR futile. The efficacy of a PSSR process depends on verification of every single item in the checklist, regardless of perceived importance.
For information about Salus Relief and Flare System Evergreening Software or other process safety information topics, visit www.smithburgess.com or call (713) 802-2647.
