Standard Practice for Obtaining Hydrostatic or Pressure Design Basis for “Fiberglass” (Glass-Fiber-Reinforced Thermosetting-Resin) Pipe and Fittings

Importancia y uso:

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 to diameter and pressure rating of the component.

Note 10: Scaling of fittings and joints should be further verified by short-time testing in accordance with Test Method D1599.

5.5 Results obtained at one set of environmental conditions shall not be used for other conditions, except that higher temperature data can be used for design basis assignment for lower application temperatures. The design basis shall be determined for each specific piping product. Design and processing can significantly affect the long-term performance of piping products, and therefore shall be taken into consideration during any evaluation.

5.6 This practice is valid for a given pipe or fitting only so long as the specimens are truly representative of that material and manufacturing process.

5.6.1 Changes in materials or manufacturing processes will necessitate a reevaluation as described in Section 12.

Subcomité:

D20.23

Referida por:

D2143-21, D5685-19, F2896-23, D2996-23, D2517-18R23, D1598-23, F1173-01R23, D3517-24, D3262-20, D2997-21, D3754-24

Volúmen:

08.03

Número ICS:

23.040.20 (Plastic pipes), 23.040.45 (Plastic fittings)

Palabras clave:

closure; cyclic pressure; design basis; fiberglass pipe; reconfirmation; static pressure;