Resealing leaking bell and spigot joint - by injecting sealant into joint using seal maintaining tooling

摘要

A leaking bell (12) and spigot (14) pipe joint is sealed by injecting a polyurethane elastomer sealant, with a viscosity between 1900 and 2800 cps. and pref. contg. 22 wt.% rubber crumb of 2 mm mesh size, directly into the joint where it flows freely before curing. The joint is accessed by drilling and tapping an injection point (18) in the bell (12) above the joint cavity and fitting a hot tap valve adaptor (20) having a passage (22) which can be closed or opened by a rotatable valve (30). The top of the adaptor is threaded (34) for attachment of a hot tap tool (28). The tool has a sealed cap (35) through which a rod (36), having an attached drill bit (32), passes, enabling the bore (18) to be drilled through to the joint cavity. For injecting the sealant, the hot tap tool is replaced by an injection gun which threads into the adaptor (20). The method and appts. enables leaking bell and spigot joints in pipes, partic. gas pipes, to be resealed without fully excavating, cleaning, and priming the exterior to apply an encapsulating resin. The seal can be made quickly and simply restoring sealing gaskets to their original condition and allowing flexing to occur to accommodate ground movements.