Document M4pbeRwd3YGkBd8jbrJgVo5ak

M 10 mCC *50920 Monsanto ,,OMN<"ltlOCAlo,<, J. C. Trube - Texas Cltv a*" September 16, 1976 Letter No. MM-2645 AN-5, Texas City CEA 2138, E-4581 GASKET SPEC CHANGE FOR VAN STONE FLANGES IN CLASS B PIPING TO : D. M. Kummer CED Constr. S. F. Gam - CED Constr. P. S. Gupton - OA-16 W. B. Hinchcliff - CED Constr. H. B. Hooper - St. Louis F4WB J. D. Knox - CED Constr. H. D. Parson (A) - 2R-48 T. P. Spruiell - 2Z R. B. St. John - St. Louis F3WA W. H. Triplett - 35LD J. M. Willock/W. H. Burke - 2R-48 .J-J r'o6re"ikl"-^0A-rjQ Confirming our conversation in a meeting attended by you, Messrs. Triplett, Gupton and myself, the AN-5 pipe specifi cations call for spiral wound gaskets to be used to seal Van Stone flanges in Class B piping. Construction experi ence to date in the field is that these gaskets are failing the hydro test. The Division requests that Blue African flat asbestos gaskets be used in all Van Stone flanges in Class B piping. If Blue African is not available, then you may substitute Garlock 7021. It is not acceptable to use two or more flat asbestos gaskets to effect the 6eal in a Van Stone flange. If one gasket won't seal it, then you must select alternate means of solving the problem. Maximum acceptable gasket thickness is 1/8". DETAILS CED first proposed that the substitute gasket material be flat asbestos with wire mesh to reduce the probability of blow out. Division agreed to accept if the mesh material of construction were stainless steel. CED later found that delivery time on gaskets with stainless steel mesh was 12 weeks. This is obviously unacceptable in view of a December 15 mechanical com pletion. CED then proposed using flat gaskets with mild steel wire mesh. Mild steel in crude AN service and in rich water service may or may not be acceptable. The wire mesh may corrode and cause the gasket to leak or even blow out. The safety risks are high and the cost to replace all of them after a few years would be high. The Division therefore prefers to use Blue African or Garlock 7021 long fiber flat asbestos gaskets. We have years of experience with this gasket in this service. This is a logical extension of a previous project decision to use Blue African flat asbestos gaskets in cyanide service. /trb SC 17051 LAM025303