Polyethylene systems in the distribution of gas [PE]

The purpose of this paper is to offer some of our experience and ideas concerning the use of. P E systems for the distribution of gas within the Emgas Region of British Gas Corporation. The Emgas Region covers an area of approximately, 17,500 sq.kilometres (7,000 sq.
miles) and supplies 1,353,000 consumers through some 21,000 kilometres (13,000 miles) of mains, Background to Piastics Before the Second World War the materials available for gas distribution systems were principally grey iron and steel, although some very limited quantities of asbestos mains had also been laid, The lead and yarn joint, used for grey iron pipes, limited the working pressure and it was not until the introduction of the flexible rubber ring compression joint in the late 1930s that grey iron pipes became suitable for other than low-pressure working. Commercially welded steel-systems had been issued to a limited extent where higher pressures were required. Steel,threaded to BSPT, was the standard material used throughout the industry for the laying of gas services, “It was due to the heavy cost of replacing corroded steel mains and services that the UK gas industry first considered the use of plastics as a material for gas distribution systems and many types were considered and tested in the 1950s,

Interest in the possible use of plastics was further stimulated when manufacture of moist coal gas declined following the introduction of very dry gas produced in catalytic reformer plants.

Dry gas has the effect of dehydrating and debenzolising distribution systems, causing the yarn or rubber in joints to shrink, thus increasing gas leakage.