Document DGkBmeE5aNz514rwzjj3BX5LN

J. MICHAEL McCOLLUM MECHANICAL ENGINEERING DIVISION PITTSBURGH OFFICE 3WPH MEMORANDUM 1980-06-12 ^u/f= < S 3 . :o '3 RE: ASBESTOS SUBSTITUTES - POTROOMS After successful testing at fttsDjKTfO we are able to recommend a non-asbestos product for use as a crucible lid gasket on the vacuus type potroon tapping crucibles. * This product Is Z-5 treated fiberglass fro* Pyrotek Inc.,** and replaces the Johns-Manville 872 or 702 gasketing material presently used in the tapping crucibles. The treatment applied to the Z-5 enables it to withstand a higher temperature than untreated fiberglass. Z-5 is actually a fabric material which Pyrotek will fabricate with the cross-section required. Several layers of the Z-5 are stitched together giving a final thickness of 1/2 inch. The proper number of these 1/2" thick tapes are then used to replace the asbestos material. AtReo*crEs>for instance, three 1/2" thick tapes, each 1-1/2" wide, are used to replace the 1-1/2" square asbestos -- - gasket. The total cost for one complete seal of Z-5 material is less than one seal of the asbestos material you are presently using. This material will replace the asbestos gasket only. If aluminum foil is twisted into a rope and used between the cruce lid and gasket, your plant will in all probability have to continue this practice. One problem we have found with this material is that the top layer wants to pull out of the lip on the cruce whenever the lid is removed. The material remains unharmed, and can be reused, but to prevent this from happening, you may want to order the Z-5 in widths 1/4" to 1/2" wider than the asbestos material. Although I do not believe we have specifically tried Z-5 as a gasket between the siphon and the cruce lid, it ought to work for that application as well. 5J. J. MICHAEL McCOLLUM JMM:scv Distribution on Page Two * Pyrotek, Inc. East 9601 Montgomery Avenue Spokane, Washington 99206 Attention: J. A. (Joe) Roberts OR Pyrotek, Inc. Box 77, R.D. 1, Claremont Road Carlisle, PA 17013 PLAINTIFF'S EXHIBIT AL-1756 ARD 007341 MEMORANDUM 1980-06-12 Page Two Distribution: G. G. Blagg - Rockdale J. R. Butler - Pt. Henry M. J. Caprio - Pittsburgh 19AB H. L. Firestone - Vancouver R. L. Graves - Pittsburgh 3WPH J. T. Hill - Warrick J. P. Hupy - Wenatchee J. H. Hutchins - Pt. Comfort D. D. McGregor - Pittsburgh 23AB T. G. O'Shaughnessy - Suriname D. J. St. Jacques - ATC B. A. Schafer - Massena R. D. Wilkins - Badin APn 0073-42