Pipe connections - jointing

Pipe connections - jointing

The connection or jointing of pipes and pipe parts may be executed in various ways depending on the material used to make the pipe and the pipe part (Fig. 2.5). For PE, fusing (heating) is the only pos-sible jointing method. This process may be carried out by a blunt heating mirror, or electrofusion may be used. When using a fusion mirror both the pipes to be joined are heated on the mirror to make them soft and adhesive; then the mirror is removed and the pipes are pressed together. The materials of the two parts are fused together and form a fixed con-nection. Resistance wire is an integral part of an electrofusion socket. When an electric current is passed the material around the wire will fuse, including the two pipe parts added to the socket, and then a fixed connection is established.

Pipes that are fused or glued together are per-manently connected and cannot be separated. If there is a need to create non-permanent connec-tions, it is possible to use flanges fused or glued to the separate pipe parts which are then screwed together. To obtain a completely watertight con-nection a gasket is placed between the parts before they are screwed together. A union is a very easy pipe connection to separate. It is always desirable to have some non-permanent connections because sometimes it is necessary to separate the pipeline for maintenance and exchange of equipment. The possibility of exchanging pipes and pipe parts in the water department of the fish farm must also be con-sidered because of the need to allow for possibleincrease in farm production and also because of the constant requirement for modernization of the equipment.

It is common to use sliding sockets in the outlet pipe. This kind of connection system can only be used on unpressurized or very low pressure pipelines (<0.2 mH₂O). If this type of connection is used on pressurized pipes they will easily slide apart.