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IMPORTANT - READ THIS FIRST Before beginning the actual assembly procedures, ver- ify all individuals involved in the installation thoroughly understand the following suggestions and precautions. Matching taper angles for the spigot and the bell make Matching taper angles allow the joint to mechanically it possible to mechanically "lock up" a joint by wedging lock up, producing a thin line of adhesive called a glue the spigot into the bell. This produces a very thin line of line. adhesive called the bond line, or glue line, that is only a few thousandths of an inch thick. In all cases, the bonding surfaces must be clean before Bonding surfaces must be clean. applying adhesive. Joint strength of the bell and spigot joint is controlled by the adhesive thickness between the two matching ta- pered surfaces. The adhesive is relatively brittle in thick sections and fails easily if the bond line is too thick. The mechanical lock determines adhesive thickness. Joint strength is controlled by the adhesive thickness - thin is good, thick is bad. Joints that are not "locked up" during installation may Mechanical locking of the joint is absolutely essential pass an initial steady pressure test but can fail pre- to develop full strength of the joint. maturely at a later date due to reduced bond strength caused by the thick adhesive. Therefore, it is essen- tial that the installation crew be familiar with the joint concept and understand the Importance of completely Inserting and locking the spigot into the bell. Using mechanical force (such as hammering against a wooden block placed against a fitting or bell end of pipe) helps achieve "lock up." NOTE: This is the same mechanical lock of matching tapers that is commonly used in machine tools. For T.A.B. (threaded and bond- ed) joints, special T.A.B. wrenches or strap wrenches are recommended to achieve the mechanical lock up of the joint. Cool weather conditions require special precautions when bonding pipe and fittings. The adhesive is very viscous (thick) when it is cool or when it is applied to cool pipe. This thick adhesive can be stiff enough to prevent complete joint "lock up." There are different installation procedures for both warm and cool weather installations. This concept is often overlooked when a crew installs piping and there are significant tempera- ture variations throughout the day or week. All bonding surfaces must be factory fresh in appear- ance. When end caps have been lost, surfaces will weather and result in loss of bond strength. When sur- faces are weathered, retaper spigots and sand bells to achieve a factory fresh appearance. NOTE: 00 NOT USE T.A.B. COUPLINGS THAT ARE WEATHERED. Using mechanical force helps achieve joint lock up. Follow the appropriate installation procedures for warm or cool weather. All bonding surfaces must be factory fresh in appear- ance.