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.