Document a1gZXoGYNQKDopmBjepZgKxpM

PLAINTIFF'S EXHIBIT ? DUP-300I CC: F. L. Hunt OfficeFile July 17, 1967 TO: K. E. KEUPER, SAFETY SUPERINTENDENT CONSTRUCTION DIVISION FROM: F. L. HUNT - W. H. ZANE.OTE> DESIGN DIVISION - POWER' In regard to the mineral wool preformed block insulation data I handed you on July 13, 1967. This material is available in block form only. Except for large lines, it cannot be used for insulation of pipe unless it is cut into lags and fabricated to fit the pipe. Since glass fiber will not cause asbestosis, it will be in corporated in project specifications. The objection to glass fiber by plant personnel is--the low resistance to abuse after installation; it is irritating to the skin; and is limited to services 70 to 350F. Therefore, we will continue with the conventional materials for temperatures above 350F until a suitable replacement is developed. The dust particle count being made at the various sites will help us determine the pipe insulation least hazardous to the health of the workmen. Since mineral slag wool. Code 114, is an acceptable material and is listed in the Engineering Standards', it will be included in the project specifications as an alternate to other acceptable blocks (such as, calcium silicate, Unibestos, etc.) where blcftk insulation is required. Sprayed Mineral Wool will replace the asbestos, spray material (Limpet) since the mineral wool contains 10% or less asbestos by volume as compared to Limpet having a 95^ or more asbestos fiber. Arrangements have been made for stress corrosion of S/S tests on mineral wool block. The mineral wool spray material has been tested and appears to be acceptable for use over S/S. WHZ/dp DUP 0900842