Tooth, Banks, Wilson
Miscellaneous # 1988 Bath
An outline is given of the main processes employed for the manufacture of multilayered GRP pipes intended for the conveyancing of both water and contaminated fluids, where high strength and light weight lead to cost and/or transportation benefits. The analysis presented, which is based on Sanders’ thin shell theory and laminate theory, enables these pipes to be designed in an optimum manner. To illustrate the use of the analysis, a support load is applied to a series of pipes with a range of layups. Particular attention is paid to the loading region where high Strains exist. It is found that these peak strains decay fairly rapidly and thus the pipes can be reinforced over relatively short lengths. The extent of this reinforcement is examined.
The advent of advanced automated manufacturing procedures has led to a notable improvement in the quality, reliability and integrity of GRP pipelines. They are therefore being increasingly used for the conveyancing of contaminated and hazardous fluids, and for the bulk transfer of water. The concept of ‘material design’ allied to their corrosion resistance and light weight gives these components an advantage over pipes manufactured using traditional materials.
Using appropriate types of glass fibre, it is possible to produce a reinforced system tailored to the requirements of the imposed loads. These, combined with the use of the most appropriate resin for the fluid conveyed, should enable an optimum design for the pipe to be achieved. At this point in time, however, the existing Standard (BS4994) does not allow such detailed calculations to be carried out. Thus the Sanders’ thin shell theory has been used, allied with specially orthotropic laminate theory, to provide a more exact understanding of such systems.
An illustrative example is provided, where a region of local support loading is examined to provide an assessment of the way in which multi-layered pipes, with different layups, handle support loadings. In this manner the area requiring possible local reinforcement can be assessed.
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