Document gbN4kGK7QaJyZ0QQy8ekOjy89

\conoco) Conoco Chemical* Company Division of Conoco Inc. PO Box 91. New Highway 25 Aberdeen. MS 39730 September 29, 1981 Mr. Charles R. Jeter Regional Administrator Region IV United States Environmental Protection Agency 345 Courtland Street, N.E. Atlanta, GA 30308 Dear Mr. Jeter: In my letter to Ms. Hanmer dated October 20, 1980, I advised the Agency of our plans to replace all double rupture disc pressure relief devices on the PVC reactors at Conoco's Aberdeen Plant with relief valve/rupture disc assemblies. These modifications were completed on the reactors in Polymerization Module No. 2 on August 17, 1981 and on the reactors In Polymerization Module No. 1 on September 18, 1981. With the completion of this project the possibility of a vinyl chloride release due to premature failure of the double disc assemblies has been eliminated. Also, since all relief assemblies now include a relief valve, the magnitude of a release due to overpressure if one should occur will be minimized as the relief valve will likely reseat as the reactor pressure decreases to the_rrelief valve set pressure. Sincerely, R. A. Frohreich Chief Process Engineer cjt c: Jerry Banks - Mississippi Bureau of Pollution Control CLM, CRM, VEM, JJH dth 000070152