Document 0J0XMBJnnEn57z3MZ62YzDr2O

/ / INTERNAL CORRESPONDENCE UJAOI-to UNION CARBIDE CHEMICALS COMPANY ' box 47i. T.<N.m.> M*1- D- A- Bernard BROWNSVILLE PLANT o.i. July 2, 1964 File H Gas Process Cep? to Mr. A. L. Barefoot - 526 Mr. 0. T. Carlisle Mr. H. B. Coons - 526 Mr. D. W. Moody, Jr. - 511 Mr. J. E. Murray/Mr. W. S. Jackson Mr. L. B. Trenholme Mr. W. M. Watkins, II - 511 MECCO S.bfc* Failure of Spiral Wound Gaskets H Gas Unit Dear fir. Bernard: We have examined several stainless steel spiral wound gaskets (FlexiXa^iic) which you sent us in an effort to determine the cause of the failure of the gaskets. Two 8-inch diameter gaskets and one 4-inch diameter gasket were found to have the spiral components broken into many pieces. One 3-inch gasket was also received which was in good condition. All four of the gaskets were in service in the preheater outlet piping at an operating temperature of approximately 500C (930F). Fig. 1 shows the condition of the 4-inch gasket with the broken stainless spirals and pieces of the asbestos packing from between the spirals. Close examination of the damaged gaskets revealed the type 304 stain less steel spiral material to be embrittled or cracked in a large number of places and the asbestos packing to be very hard, brittle, and shiny black. Metallographic examination of the stainless spiral revealed the attack to be intergranular corrosion of sensitized 304 stainless steel. An example of this corrosion may be seen In Fig. 2. With the temperatures involved, It appears that some decomposition of the asbestos packing and its filler material has taken place, releasing some corrosive constituent such as HC1. By comparison, the 3-inch gasket was found to be built of 316 stainless spirals and the asbes tos packing was still soft and fibrous in nature. The three gaskets which failed were part of the original material ordered for the unit, while the 316 gasket was taken from the Brownsville plant stores. A review of the Flexitallic catalog Indicates that they have two types of asbestos which are supplied in their gaskets. One is the Canadian asbestos which is compounded with some filler material, and the second is a blue African asbestos. The 3l6 gaskets at the Brownsville plant use the blue African asbestos filler. Because of the difference in the appearance of the asbestos packing in the used gaskets, we have assumed that the 504 gaskets which failed contained the Canadian asbestos. The organic filler, or polymer material, which was used to bind the fibers together, is believed to have caused the corrosion of the stainless steel. ' UCC 015676 PLAINTIFF'S EXHIBIT UC-2074