A polyethylene for a pipe and a joint of the present invention satisfies the following characteristics (1) to (5): Characteristic (1): a melt flow rate at a temperature of 190 C. and a load of 21.6 kg (HLMFR) is 5 to 20 g/10 minutes, Characteristic (2): a density (D) is 0.954 to 0.960 g/cm.sup.3, Characteristic (3): a ratio of weight-average molecular weight (Mw) and number-average molecular weight (Mn) (Mw/Mn) measured by gel permeation chromatography (GPC) is 15 to 27, Characteristic (4): a rupture time at 80 C. and 5 MPa by a full notch creep test (FNCT) is 150 hours or more, and Characteristic (5): a Charpy impact strength (CIS) measured at 20 C. is 8.5 kJ/m.sup.2 or more.

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.

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.

A method for coaxially connecting a first plastic tube (10, 110) to a second plastic tube (20, 120), said plastic tubes (10, 20) in particular being provided as part of a medical catheter (102), the two plastic tubes (10, 20) being connected by way of a tubular connecting piece (50), characterized in that the first plastic tube (10) and/or the second plastic tube (20) are integrally molded from the outside onto the tubular connecting piece (50) using a forming process such that an adhesive and/or positive connection is produced.

A mechanical coupling between a straight pipe end and a socket fitting comprises a seal ring and a locking ring disposed within the interior of the socket. The locking ring has a generally frustoconical shape with a plurality of corrugations extending circumferentially thereabout, the corrugations presenting inner edge portions engaging the outer annular surface of the pipe end and outer edge portions engaging the interior annular surface of the socket for opposing withdrawal of the pipe end axially outwardly from the socket. In an advantageous embodiment, the locking ring is assembled with a support disk to optimally orient the locking ring with respect to the fitting and the pipe end.

A mechanical coupling between a straight pipe end and a socket fitting comprises a seal ring and a locking ring disposed within the interior of the socket. The locking ring has a generally frustoconical shape with a plurality of corrugations extending circumferentially thereabout, the corrugations presenting inner edge portions engaging the outer annular surface of the pipe end and outer edge portions engaging the interior annular surface of the socket for opposing withdrawal of the pipe end axially outwardly from the socket. In an advantageous embodiment, the locking ring is assembled with a support disk to optimally orient the locking ring with respect to the fitting and the pipe end.

A fastener free joining system includes a first tubular shell component having a first plurality of teeth defined in a first free end, each tooth extending along a respective tooth axis oblique to an axis of the first component by an angle . The first plurality of teeth is configured to engage with a plurality of complimentary teeth defined in a second free end of a second tubular shell component, such that, when engaged, the first plurality of teeth is configured to remain engaged with the plurality of complimentary teeth under axial load.

An installation connection device for installation in a housing opening includes a body, which has an installation portion, and a connection portion. The installation portion has a sealing means designed for sealing with respect to the housing opening or with respect to the housing wall containing the housing opening and is delimited at the transition to the connection portion by a stop structure. The installation portion also has fixing structures designed to fix the installation portion in the housing opening or to the wall surrounding the housing opening. On the side of the stop structure opposite from the installation portion, a collar having a peripherally closed wall is integrally formed on the stop structure. In the body, a holder is removably supported and fixed without a seal, which holder is designed to releasably receive, without a seal, one or more first line connection devices, which each provide a connection point of a line connected thereto for a corresponding second line connection device provided in a fit-on connection device coupled to the connection portion. The holder is supported in the body such that the first line connection devices are accessible within the space surrounded by the collar wall.

An installation connection device for installation in a housing opening includes a body, which has an installation portion, and a connection portion. The installation portion has a sealing means designed for sealing with respect to the housing opening or with respect to the housing wall containing the housing opening and is delimited at the transition to the connection portion by a stop structure. The installation portion also has fixing structures designed to fix the installation portion in the housing opening or to the wall surrounding the housing opening. On the side of the stop structure opposite from the installation portion, a collar having a peripherally closed wall is integrally formed on the stop structure. In the body, a holder is removably supported and fixed without a seal, which holder is designed to releasably receive, without a seal, one or more first line connection devices, which each provide a connection point of a line connected thereto for a corresponding second line connection device provided in a fit-on connection device coupled to the connection portion. The holder is supported in the body such that the first line connection devices are accessible within the space surrounded by the collar wall.