Document vBr6gXmZzVXj3mL6dvjJ16D6m

T*14o MEMORANDUM Dr. Neill K. Weaver took Fred S. Venable | EXHIBIT * EXX-17 usjtcr Insulators' Exposures to Asbestos DATS BATON ROUSE. LA. 5/13/64 rux no. Many of the insulating materials used in the refinery such as cements, preformed sections, elbows and coverings contain varying amounts of asbestos fibres together with glass, magnesia and cement. In the 1940s and early 1950s, the insulation used for high temperature lines and equipment consisted of such asbestos - containing materials as: 302 Cement - Johns-Manville Unibestos - Pittsburgh-Coming Thermobestos - Johns-Manville Calsite - Ruberoid Company Careytearp - Philip Carey Company Asbestos felt papers and asbestos sponge felted insulation was also used to wrap cork insulated lines on cold piping. The loose asbestos cement was received in bags, dumped into mixing troughs, stirred with water and applied wet. Some asbestos dust would likely be released in the first stage of this mixing. Much pre-formed asbestos-magnesia insulation has been used over the years, along with preformed elbows and other non-linear configurations. These are sometimes cut and fitted by hand using hand saws (formerly power sawing was done about 10 years ago). Although most insulation work is outdoors, occasional jobs are done in confined or semiconfined spaces such as beneath structures, inside compressor houses, etc. which may have given rise to periodic high exposures. On the average, however, it is felt that exposures to asbestos was low due to such factors as work speed, wet application and good ventilation. Respirators were available for use by the insulators but in view of the low dust concentrations encountered, it is not likely that they were worn for appreciable periods. In recent years, newer insulation materials have been gaining in popularity. These are mainly foam glass and polyurethane preformed sections. Some asbestos - calcium silicate insulation (Owens-Coming Kaylo) is used today. Preformed sections are generally available. Asbestos cements are used by Masons principally at this time. Only Johns Manville 450 Asbestos cement is used by insulators. In addition to the work of the insulator in applying asbestos materials, it should be remembered that their work of removing old insulation is likely to produce dry dust exposures, also. 0022