Design Engineers use various tools that instrumental in safety planning, installation, execution and operation of the entire plastic piping systems. One such vital tool is the service life prediction or estimation tool that ensures the safety and efficiency of the entire process of the piping system. Factors like resistance to chemicals and stress from the external and the internal environment determine the service life of the piping system. Internal pressure or any external factor such as bending, embedment or shear can be instrumental in causing stresses. The nature of the stresses might be varying or they remain constant. Stresses of a material can be caused due to various factors like internal pressure surges, temperature changes, and varying loads from tidal flows, traffic, and so many other similar issues. Besides, the constant resistance to the various internal or external temperature, chemicals and variations can amalgamate into affecting the service life of the piping system. To deal with this, hydrostatic stress-rapture testing effectively helps to estimate the resistance to stress, which is a component of the service life, caused by internal pressure. A conventional short-term tensile strength test cannot determine the long-term strength of any thermoplastic compound. As such, effective testing and evaluation methodologies have been developed that consider factors beyond the stress rapture response of thermoplastics. ISO 9080 are ASTM D 2837 are therefore developed to estimate the long term strength of a plastic pipe material. The tests and evaluation methodologies delve further into the consideration of the potential changes in failure mode of the material when subjected to other factors causing stresses such as by loadings caused by other than hydrostatic pressures. This comprehensive and in-depth evaluation procedure helps the engineers to derive better forecasts on the long-term strength of these materials to ensure safety while using for pressure pipe application. "…effective testing and evaluation methodologies have been developed that consider factors beyond the stress rapture response of thermoplastics.” |
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