This specification covers fabrication techniques for cellular glass block into billets to fabricate pipe and tubing insulation. The optimization of the thermal performance of installed cellular glass insulation systems is discussed. This is best achieved by limiting the number of joints, in particular through joints. Cellular glass pipe and tubing insulation shall be fabricated from the minimum number of insulation blocks. Sectional pipe insulation shall contain not more than four through joints per full section of insulation, excluding the half section mating plane. Fabrication adhesive shall be hot asphalt, Type II operating at some temperature. For operating temperatures above ambient, fabrication adhesive shall include but not be limited to Type II hot asphalt, elastomeric asphalt, or gypsum-based cement of the type and grade specified. Fabricating adhesive shall be applied such that there is 100% coverage of adhesive on the mating surfaces. Billet and miter construction shall conform to the following: insulation blocks or sections shall be hand rubbed if necessary to fit prior to bonding and bond joints shall be made with a full depth of approved adhesive. Bond joints can be classified as "non-through" joints which start at the outside circumference and run continuously in a straight line to the opposite side terminating at the outside circumference. "Through" joints start at the outside circumference and runs continuously in a straight line to the opposite side and terminates at the inside circumference. All segmented pipe insulation shall be edge trimmed at the fabrication site. Either a grinder or a saw shall be used to edge trim segmented pipe insulation. If segmented pipe insulation is edge trimmed using a saw blade, edges shall be rubbed to remove uneven patterns caused by flexing blade where needed. Fittings for all sizes shall be either factory ground or factory mitered.