Abstract: A molding apparatus for making a plastics pipe fitting or pipe coupling by injection-molding the plastics pipe fitting or coupling body, injection-molding at least one sealing ring separately but substantially simultaneously, and bringing the body and sealing ring together directly after the molding while these components are still in a hot as-molded state, so that a direct thermal bond is formed between them comprises respective injection-molding cavities for the body and sealing ring, and a reversible support for carrying the sealing ring out of its mold and into contact with the molded body. The respective molds are opened and the components are not stripped but are brought together for bonding while still in position on respective mold members, thereby eliminating intermediate handling and ensuring that the molded components remain clean and of accurate shape and dimension as they are brought together.

Abstract: A clay or similar pipe has a coupling socket at one end formed by a shrink-fitted plastics sleeve. A sealing ring or band is interposed between the sleeve and the pipe surface. External compression is applied to the plastics sleeve over the sealing member during shrinkage of the sleeve. This compresses the sealing member and ensures reliable sealing without requiring the use of an additional bonding or sealing composition.Alternatively or additionally, a shrink-fitted plastics socket on a claywear or similar pipe end may have a region spaced from the pipe end, provided with a seal ring, and not subjected to shrink-fitting. The seal ring provides a secondary seal.

Abstract: A pipe coupling formed by a tubular plastic member having at one end a portion of increased diameter defining an inwardly facing annular recess, and an annular sealing ring bonded therein by a foot portion substantially filling the recess and having a sealing head portion projecting partway across the interior of the coupling and secured to such foot portion by a neck portion. The seal ring configuration lends itself to injection molding of the assembly.