Fundamentals # 1970 Southampton
The above definition is as applicable to the plastics materials of the 20th century as it was in the days of the Victorian engineers. In the present case the "given state" is that of maintaining an adequate level of properties for performing a desired function in any given application. To put the problem in more concrete terms, the object of this paper is to review those factors which affect the lasting power of plastics pipes in service and which should be taken into account when choosing a particular pipe material to do a specific job. One of the most important of these factors, the long-term effect of mechanical stresses, is dealt with elsewhere and wi II not be touched on here: we are concerned with a complex mixture of rather less quantifiable properties associated with the environments in which pipes are required to perform. These can be grouped under the headings of weathering, temperature effects, corrosion, biological attack and abrasion; together with a miscellany of unpredictable hazards associated with the installation of the pipe.