Van der Vegt
Fundamentals # 1970 Southampton
The family of thermoplastics has, over the past few decades, been :I>e fastest growing group of materials, the overall growth rate of plastics production and consumption being about 15% per annum. An approximately constant fraction of the total plastics production (about 3%) is applied in pipes, in other words, the consumption of plastics pipes also grows at a rate of about 15% per annum. The present plastics pipe consumption in the UK is about 44,000 t~ns/~ear, and i t i s estimated that in the forthcoming 15 to 20 years it will grow to a saturation level of 300,000 to 400,000 tons/year, which will then cover all the plastics pipes applications that are potentially possible.
We appear to be living in the middle of a relatively short period of time in which, in an important technical field, traditional materials are, at the greatest possible speed, being replaced by a new group of materials which 30 years ago still belonged to the curiosities. The reason for this remarkable phenomenon lies in the fact that plastics posses a unique combination of properties which are of prime importance for pipes; they are largely noncorrosive, light, cheap, and easy to install. On the other hand it should not be forgotten that the same plastics have a number of serious deficiencies: they are not very strong, and they are temperature-sensitive and timedependent in their mechanical properties.
Hence, for a successful use of plastics as pipe materials, it is essential to find a proper balance between the strong points and the weak points, by a careful selection of polymer type and grade for each field of application.
In this paper we shall consider the advantages and limitation of the various plastic pipe materials into some detai I, and discuss the new developments made to improve some of the deficiencies.