Abstract: An elastomeric lip seal joint for sealing the inner liner and grout layers when joining two sections of multiwall pipe having an outer steel casing and an inner liner. The ring-shaped lip seal joint comprises a gasket with insulating material completely covering its outer surface. The insulating material is capable of shielding the gasket from the heat produced when the sections of outer steel casing are welded together. The use of the lip seal joint simplifies the process of joining sections of multiwall pipe. Each side of the lip seal joint is inserted into one of the annular voids at each end of the pipe, thereby sealing the inner liner and grout. A single circumferential weld then joins the outer steel casing. The gasket remains intact during the welding process due to the presence of the insulating material.

Abstract: An elastomeric lip seal joint for sealing the inner liner and grout layers when joining two sections of multiwall pipe having an outer steel casing and an inner liner. The ring-shaped lip seal joint comprises a gasket with insulating material completely covering its outer surface. The insulating material is capable of shielding the gasket from the heat produced when the sections of outer steel casing are welded together. The use of the lip seal joint simplifies the process of joining sections of multiwall pipe. Each side of the lip seal joint is inserted into one of the annular voids at each end of the pipe, thereby sealing the inner liner and grout. A single circumferential weld then joins the outer steel casing. The gasket remains intact during the welding process due to the presence of the insulating material.

Abstract: A method for installing a fiberglass or stainless steel liner into a steel casing which results in a reduction of strain on the casing. Conventional means are used to place the liner into the casing and to fill the annular space with cement. Thereafter, maximum design operating pressure on the liner is maintained while the pressure on the annular space is reduced; maintenance of those pressures keep the liner in an expanded state while the grout cures. As a result, the liner shares the load with the casing; pressure from the fluids contained in the system during operation is not transferred to the casing through the grout until the liner's preset internal pressure is reached. The use of the method greatly reduces the possibility of flowline failure.

Abstract: The invention is directed to a double-wall steel pipe joint. Each section of double-wall steel pipe has a steel outer casing and a steel inner carrier pipe. The completed joint comprises a steel joint ring fitted within the annular space at the end of each double-wall steel pipe section. The combination of locking serration and epoxy bonding join and seal the inner steel pipe to the bore of the joint ring, without welding. Welding joins the ends of the sections of outer casing.