ASTM D2992-22 PDF

SIGNIFICANCE AND USE 5.1 This practice is useful for establishing the hoop stress or internal pressure versus time-to-failure relationships, under selected internal and external environments which simulate actual anticipated product end-use conditions, from which a design basis for specific piping products and materials can be obtained. This practice defines an HDB for material in straight, hollow cylindrical shapes where hoop stress can be easily calculated, and a PDB for fittings and joints where stresses are more complex. 5.1.1 An alternative design practice based on initial strain versus time-to-failure relationships employs a strain basis HDB instead of the stress basis HDB defined by this practice. The strain basis HDB is most often used for buried pipe designs with internal pressures ranging from 0 to 250 psig (1.72 MPa). 5.2 To characterize fiberglass piping products, it is necessary to establish the stress versus cycles or time to failure, or pressure versus cycles or time to failure relationships over three or more logarithmic decades of time (cycles or 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 shall be established. 5.3 Pressure ratings for piping of various dimensions at each temperature may be calculated using the HDS determined by testing one size of piping provided that the same specific process and material are used both for test specimens and the piping in question. 5.4 Pressure ratings at each temperature for components other than straight hollow shapes may be calculated using the HDP determined by testing one size of piping provided that (1) the specific materials and manufacturing process used for the test specimens are used for the components, (2) for joints, the joining materials and procedures used to prepare the test specimens are used for field joining, and (3) scaling of critical dimensions is related ... SCOPE 1.1 This practice establishes two procedures, Procedure A (cyclic) and Procedure B (static), for obtaining a hydrostatic design basis (HDB) or a pressure design basis (PDB) for fiberglass piping products, by evaluating strength-regression data derived from testing pipe or fittings, or both, of the same materials and construction, either separately or in assemblies. Both glass-fiber-reinforced thermosetting-resin pipe (RTRP) and glass-fiber-reinforced polymer mortar pipe (RPMP) are fiberglass pipe. Note 1: For the purposes of this standard, polymer does not include natural polymers. 1.2 This practice can be used for the HDB determination for fiberglass pipe where the ratio of outside diameter to wall thickness is 10:1 or more. Note 2: This limitation, based on thin-wall pipe design theory, serves further to limit the application of this practice to internal pressures which, by the hoop-stress equation, are approximately 20 % of the derived hydrostatic design stress (HDS). For example, if HDS is 5000 psi (34 500 kPa), the pipe is limited to about 1000-psig (6900-kPa) internal pressure, regardless of diameter. Note 3: Where long (continuous) glass fibers are intentionally placed to resist the planned pressure load case (that is, free end pressure testing and 654.7° fiberglass windings) the results from this practice may be overly conservative in predicting long term fiberglass pipe performance when the same pipe is operated at lower (non-damaging) stresses typical in normal pipeline applications. Note 4: All data points in the analysis shall be of the same failure mode. Where plastic creep of the resin leading to pipe failure is precluded by unintended resin matrix cracking or other unanticipated modes of failure, this practice may not accurately represent the pipe’s life expectancy. 1.3 This practice provides a PDB for complex-shaped products or systems where complex stress fields seriously inhibit the use of h...