【国外标准】 Standard Test Method for Time-to-Failure of Plastic Piping Systems and Components Under Constant Internal Pressure With Flow (Withdrawn 2018)

The data obtained by this test method are useful for establishing pressure, or hoop stress where applicable, versus failure-time relationships, under independently controlled internal and external environments that simulate actual anticipated product end-use conditions, from which the design basis (DB) for piping products or materials, or both, can be determined. (Refer to Test Method D2837 and Practice D2992, and Appendix X1 of this test method.)Note 3—Reference to design basis (DB) in this test method refers to the hydrostatic design basis (HDB) for material in straight hollow cylindrical shapes where hoop stress can be easily calculated, or is based on applied pressure design basis (PDB) for complex-shaped products or systems where complex stress fields seriously prohibit the use of hoop stress.In order to characterize plastics as piping products, it is necessary to establish the stress-to-rupture-time, or pressure-to-rupture-time relationships over two or more logarithmic decades of time (hours) within controlled environmental parameters. Because of the nature of the test and specimens employed, no single line can adequately represent the data. Therefore, the confidence limits should be established.Results obtained at one set of environmental conditions should not be used for other conditions, except that higher temperature data can be used for a design basis assignment for lower application temperatures, provided that it can be demonstrated that the application conditions present a less stringent environment. The design basis should be determined for each specific plastic material and each different set of environmental constraints. Design and processing can significantly affect the long-term performance of piping products, and therefore should be taken into consideration during any evaluation (see Appendix X2).Specimens used must be representative of the piping product or material under evaluation (see Appendix X2).1.1 This test method covers the determination of the time-to-failure of plastic piping products under constant internal pressure and flow.1.2 This test method provides a method of characterizing plastics in the form of pipe, components, and systems under any reasonable combination of internal and external temperatures and environments, under the procedures described.1.3 This test method can be used to characterize the tested plastic materials or products, or both, on the basis of pressure-, or stress-rupture data developed under the conditions prescribed.1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.