Abstract: An underground double containment system consists of a concrete outer containment receptacle housing a primary fluid flow pipe which extends therethrough and is slidably supported on double I-beam structures within the concrete receptacle. The concrete receptacle can be provided with a removable cover providing access to the primary piping in modular sections defined by the boundary of the receptacle. The primary piping can expand or move along the longitudinal axis of the concrete receptacle relative to the concrete receptacle enabling thermal of the primary and containment piping outside of the receptacle, which can be formed from different materials, as the outer containment pipe can be connected to the interior of the receptacle at the juncture of the receptacle and the primary piping. A plurality of concrete receptacles can be joined at an angle of between 0.degree. and 180.degree. to provide a double containment system for nonlinear primary pipes.

Abstract: The centering support assembly features a half moon shaped support base with two upright stanchions at opposite sides of the base, providing proper spacing between the base support and a crosshead clamping piece. The entire assembly is bolted together by bolts received through the crosshead and each stanchion, which is threadedly received in the base. One or more inner or primary pipes may be supported between the stanchions, which permit proper deflection of the pipes relative to each other and lateral deflection, if necessary, and similarly, relative to the outer containment pipe. The cross-piece and half moon base portion of the centering support assembly fit within the inner diameter of the outer containment pipe, with the crosshead piece spaced from the inner diameter to permit deflection of the outer pipe relative to the primary pipe or pipes under load.

Abstract: An underground double containment system consists of a concrete outer containment receptacle housing a primary fluid flow pipe which extends therethrough and is supported on inverted T-beam structures within the concrete receptacle. The concrete receptacle can be provided with a removable cover providing access to the primary piping in modular sections defined by the boundary of the receptacle and flexible curved tubes opening in the wall of the receptacle through which the primary piping module sections can be removed from the receptacle or held for repair/maintenance.

Abstract: An access housing is provided between segments of an outer containment pipe of a double containment pipe assembly through which the flanged ends of a primary pipe may be accessed with the ability to readily assemble and disassemble the inner piping system in modular sections.

Abstract: A double containment pipe joint assembly is provided with an inner pipe and an outer or containment pipe secured in concentric relation. The pipe joint assembly includes a fitting having end surfaces on concentric flanges which can be secured to a length of a primary and containment pipe at intervals along the pipeline wherein sections of the pipeline can be removed and repaired without the necessity of removing the whole pipeline. The concentric flanges are joined by a thickened divider ring which provides smooth fillets at its juncture with the flanges to reduce thermal stresses on the fitting.

Abstract: A centering support for a double containment pipe assembly consists of a three-piece assembly including an outer ring and a pair of mirror-image inner rings having tabs which are inserted into holes in the outer ring from opposite sides. The diameter of the outer ring is slightly smaller than the inner diameter of the outer pipe or conduit of the double containment pipe assembly and is inserted into an outer pipe at spaced locations therealong. The inside diameter of the inner rings are slightly wider than the outside diameter of the primary or inner pipe and they may receive therethrough the inner pipe. The inner rings and outer ring can be formed from dissimilar materials which are weldable to the outer pipe and inner pipe, respectively, at selected support points.

Abstract: A double containment pipe joint assembly is provided with an inner pipe and an outer or containment pipe secured to the joint assembly in concentric relation. The pipe joint assembly includes a first and second fitting coupled together to present end surfaces which can be secured to a length of a primary (inner) and containment (outer) pipe at intervals along the pipeline wherein sections of the pipeline can be removed and repaired without the necessity of removing the whole pipeline, while anchoring the pipes together at spaced locations along the pipeline. The arrangement further allows the pipes to be formed from different materials compatible with the pipe fittings and precludes the necessity of providing flanges on the inner and containment pipes so they can be secured in concentric relationship, lessening the chance for failure. One of the inner and outer fittings has two sections (either separate or cast in one piece) which are secured in mirror-image relation to a ring on the other section.