The present invention relates to a process for the production of at least two-layer thermoplastic foam sheets via thermal welding of at least two thinner thermoplastic foam sheets. In the process of the invention, at least two heating elements are conducted on mutually offset planes between the surfaces to be welded of the thinner thermoplastic foam sheets, and the foam sheets here do not touch the heating elements. The number of layers of the thermoplastic foam sheet is per se a result of the number of thinner thermoplastic foam sheets that are thermally welded to one another. If by way of example three thinner thermoplastic foam sheets are thermally welded to one another, a three-layer thermoplastic foam sheet is per se obtained, and if there are four thinner thermoplastic foam sheets the result is accordingly per se a four-layer thermoplastic foam sheet.

A pipe adapter includes a first tubular element having a first portion, a second portion axially adjacent the first portion, and a securing portion adjacent an end of the second portion opposite the first portion, the second portion defining a socket; a second tubular element having a first portion and a second portion axially adjacent the first portion, the first portion defining a distal end sized for insertion into the socket and having a radially extending stop; an annular sealing member. The securing portion is formed integrally with the second portion of the first tubular element and has a flange portion contacting the stop to secure the second tubular element axially relative to the first tubular element while also allowing the second tubular element to rotate relative to the first tubular element.

A test piece configured for the implementation of a method for evaluating an assembly by welding of parts made of thermoplastic materials, wherein the test piece includes at least two parts based on thermoplastic materials having surfaces to be welded that are at least partially placed opposite one another and respective free surfaces, wherein at least one of the parts is a perforated reference part including at least one perforation.

Provided is an electric power control apparatus of an electrofusion coupling pipe using a conductive polymer composite as a heating element and a method of controlling electric power using the same. The electric power control apparatus supplies electric power to the electrofusion coupling pipe using a conductive polymer composite as a heating element to detect resistance variation of the conductive polymer composite and then controls electric power supplied to the synthetic resin pipe electrofusion coupling pipe on the basis of the detected resistance variation.

Resilient and elastic members are sandwiched between a first sheet material and a second sheet material and overlapping areas of the first sheet material and the second sheet material are not joined together at CD direction both end portions but are joined together at an area between the both end portions, thereby to form a belt-like continuous elastic belt. The elastic belt is cut in the middle of a CD direction thereof between the resilient and elastic members at a joined position of the first sheet material and the second sheet material to form a pair of divided elastic belt. CD direction positions of these divided elastic belts are exchanged or the divided elastic belts are vertically reversed. A ventral side outer body and a dorsal side outer body are formed from the pair of divided elastic belts.

The present disclosure provides a welded body having a connecting structure formed by welding a first molded body and a second molded body, wherein the first and second molded bodies contain at least one copolymer selected from the group consisting of a tetrafluoroethylene/fluoro (alkyl vinyl ether) copolymer and a tetrafluoroethylene/hexafluoropropylene copolymer, and wherein the connecting structure has a liquid contact surface to be in contact with a liquid having a solubility parameter of 14 to 35 (MPa).sup.1/2, a welded part formed in the connecting structure is not exposed to the liquid contact surface, and the number of particles of 30 nm or larger to be eluted from the liquid contact surface in the connecting structure is 1,000 particles/ml or less.