Abstract: A secondary containment piping system is composed of a plurality of modules of concentric pipe. The inner pipe carries fluid being transported, and the outer pipe provides secondary containment of fluid leaking from the inner pipe. The module consists of a length of inner pipe centred in a length of outer pipe by a series of spiders or ribs, fastened to one or both of the pipes. The ends of both inner and outer pipes are coplanar and perpendicular to the axis of the module. Successive modules are joined by simultaneously welding the inner and outer pipes of one module to the corresponding pipes of an adjacent module, the preferred material for the pipes is HDPE and the welding is accomplished using electric fusion welding techniques.

Abstract: An improved welding rod having a solid homogeneous core of thermoplastic material and a resistance element comprised of a plurality of wires is presented with a method and apparatus for forming the welding rod. The welding rod is positioned between members of the thermoplastic material to be welded and a current and pressure is applied to the resistance element causing the thermoplastic material of the solid core and the adjacent thermoplastic members to fuse and form a unitary weld. Simultaneously the electrical resistance element is embedded in the weld, mechanically reinforcing and strengthening the connection. There is also disclosed a method for electric fusion welding of thermoplastic members wherein the welding rod is pre-attached to one of the thermoplastic members.

Abstract: An improved welding rod having a solid homogeneous core of thermoplastic material and a resistance element comprised of a plurality of wires is presented with a method and apparatus for forming the welding rod. The welding rod is positioned between members of the thermoplastic material to be welded and a current and pressure is applied to the resistance element causing the thermoplastic material of the solid core and the adjacent thermoplastic members to fuse and form a unitary weld. Simultaneously the electrical resistance element is embedded in the weld, mechanically reinforcing and strengthening the connection. There is also disclosed a method for electric fusion welding of thermoplastic members wherein the welding rod is pre-attached to one of the thermoplastic members.

Abstract: A pipeline system with a localized environment for preventing, detecting, and containing leakage from a subterranean pipeline transporting hydrocarbon liquids and gases is disclosed. A steel pipe is enclosed in a sleeve of high density polyethylene and overlaid with a layer of geotextile material. Positioned in the interstitial space between the pipe and sleeve is a layer of geotextile material impregnated with hydrated lime which dissolves in the presence of water to create a highly alkaline solution to protect the pipe. Also positioned adjacent the inner layer are leak sensors/monitors for detection of leaks of hydrocarbon fluids and aqueous solutions.

Abstract: An improved system for containment and detection of leakage of petroleum products from a subterranean storage tank is disclosed wherein the tank is provided with leak sensing means positioned at one end of the tank and the tank, together with the leak sensor, is enclosed in an impervious enclosure which is sealed about the tank to prevent actuation of the leak sensor except due to leakage from the tank. In one form the leak sensor may be housed in a perforated duct which extends through and is sealed within the enclosure permitting access to the leak sensor and the interior of the enclosure in the event that a leak is detected. A preferred material for use in making the enclosure is welded linear high density polyethylene (HDPE). In a second preferred form, a drainage mesh is positioned between the tank and the enclosure to ensure that any leakage from the tank drains to the leak sensor, and an absorbent strip is positioned beneath the tank and inside the enclosure to conduct leakage to the sensor.

Abstract: An improved system for containment and detection of leakage of petroleum products from subterranean tanks or lines is disclosed wherein the tanks or lines are provided with a leak sensing means positioned adjacent the tank, and the tank or line together with the leak sensor is enclosed in an impervious enclosure which is sealed about the tank or line to prevent actuation of the leak sensor except due to leakage from the tank. In a preferred form the leak sensor is housed in a perforated duct which extends through and is sealed within the enclosure permitting access to the leak sensor and the interior of the bag in the event that a leak is detected. A preferred material for use in making the enclosure is welded high density polyethylene (HDPE).