Testing and Processing # 1982 York
Stress relaxation in PVC and PEH sewage pipes was measured for more than 10 years, and the relaxation data were extrapolated by means of the Findley creep model up to 50 years. The influence of pipe dimensions, as well as that of the degree of deflection in the pipe are being discussed. It has been observed that the final extrapclated relaxation modulus strongly depends on the time the relaxation measurements have been continued. Presumably long-term measurements lead to results with better relevance with oractice.