Pipes, Tube, and Conduits

For plastic pipes, LDPE and LLDPE are used less than HOPE. Typical applications are irrigation lines or flexible tubes with small dimensions. 

A PE system is normally limited to pressures of 1 MPa for gas and 1.6 MPa for water applications to avoid excessively thick products. The upper service temperature limit is normally around 40-50 °C but this is extended by the use of crosslinked PE (XPE) to around 80 °C or more for liner applications. The development of reinforced and multilayer pipe systems continues to extend such limits. The size range for water is 16-1600 mm, while for gas it is normally up to 630 mm. 

XPE is used for water supply lines (cold and hot potable water distribution being consistent with the requirements of the Environmental Quality Act) and irrigation pipelines. It has been used since about 1985 in the USA and earlier in Europe. There are many reasons why PE pipes are popular. 

Aluminium/plastic composite pipes for heating and sanitary applications are manufactured in five layers two layers of silane-crosslinked HOPE with an aluminium core and two adhesive layers. The aluminium layer provides an oxygen barrier. 

EIDPE pipes reinforced with aramide tape can withstand 7.0 MPa operating pressures for service lives of 50 years. Multilayer pipes are made of a standard PE inner layer wrapped with aramide tape. 

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Metal pipe, tubing, and conduit Not less than 0.15 gpm/ft2 of surface hrea and directed toward the undersides. 

Statistics — U.S. Shipments of Polyethylene Pipe, Tube and Conduit, Plastics Pipe Institute, 1999. 

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