This investigation began after a 9.6 pound vinyl chloride release from an improperly installed rupture disc (RD). The rupture disk had been improperly installed per original design, and its identification tag had been improperly inserted in the rupture disc holder. Just last night I posted an incident where a “low pressure” vessel catastrophically failed because it did not have adequate relief protection when its RD was installed upside down! Darn those pesky relief devices.
Respondent is a corporation authorized to do business in the State of Texas. Respondent owned and operated a chemical manufacturing. Respondent manufactures polyvinyl chloride (PVC) resin using a suspension polymerization process. The suspension polymerization process combines vinyl chloride monomer (VCM) with suspending agents, initiators, and solvents in a closed reaction vessel to produce PVC. Polyvinyl Chloride (PVC) is identified at 40 CFR Part 68.130 as a flammable regulated substance with a threshold quantity of 10,000 pounds. Respondent produces, stores, or handles a regulated substance, vinyl chloride, in an amount over the threshold quantity of 10,000 pounds in a process unit. Based on the quantity of regulated substances present at the facility, the facility’s NAIC’s code, and an evaluation of off-site receptors, the covered processes at Respondent’s facility are subject to Program 3 of the RMP regulations. The suspension polymerization process takes place in a closed vessel. To avoid over-pressurization of the vessel, the contents of the vessel must be continuously mixed with a motorized agitator. The motor is connected to a torque converter, which is connected to and controls the speed of the agitator in the reactor vessel. When the agitator stops during a batch, the pressure rises rapidly and the batch must be inhibited to control the pressure. The inhibitor system for the reaction vessel consists of four tanks filled with a chemical that will stop the suspension polymerization reaction, thus preventing over-pressurization. The batch suspension polymerization process, including the motorized agitator and inhibition system, is a covered process subject to RMP Program 3 requirements.
At 4:41 pm on May 28, 2015, the oil pump on the torque converter failed, causing the torque converter and agitator on reactor PI2251B to shut down. Due to the lack of agitation, the pressure in the reactor vessel begun to increase rapidly. At 4:50 PM, Respondent manually inhibited the batch.
One of the inhibitor tanks, TK-2251B operates differently than the three other tanks in the inhibition system for the process. Where as the other tanks are charged by nitrogen pressure, TK-2251B operates by equalizing with the reactor pressure to charge.
At 4:53 PM, an area wide monitoring system monitor detected a concentration of vinyl chloride above 5 ppm, indicating a leak. Operations personnel were dispatched to determine the source of the leak.
Operations personnel determined that the source of the leak was a rupture disc flange associated with TK-2251B. The rupture disk had been improperly installed per original design, and its identification tag had been improperly inserted in the rupture disc holder. Operations personnel tightened the flange to stop the leak of vinyl chloride at 5:10 PM. This caused a release of 9.6 pounds of vinyl chloride.
The facility failed to perform appropriate checks and inspections to assure that equipment is installed properly and consistent with design specifications and the manufacturer’s instruction by failing to install the rupture disc per the original design and by improperly inserting the rupture disc ID tag in the rupture disc holder.
On May 28, 2015 Respondent failed to conduct appropriate checks and inspections to assure that equipment is installed properly and consistent with design specifications and the manufacturer’s instructions in violation of 40 CFR 68.73(f)(2).
Upon consideration of the entire record herein and upon consideration of the size of the business, the economic impact of the penalty on the business, the violator’s full compliance history and good faith efforts to comply, the duration of the violation, payment by the violator of penalties previously assessed for the same violation, the economic benefit of noncompliance, the seriousness of the violation, specific facts and equities, litigation risks, and other factors as justice may require, the parties agree that $33,000 is an appropriate penalty to resolve this matter.
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