ISO 7509:2015 pdf download.Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes — Determination of time to failure under sustained internal pressure
1 Scope
This International Standard specifies a method for determining the time-to-failure of glass-reinforced thermosetting plastics (GRP) pipes under internal hydrostatic pressure at a specified temperature. The external environment can be air or water.
NOTE For other internal or external environments, the referring standard is to specify any additional requirement.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions
ISO 10928, Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes and fittings —Methods for regression analysis and their use
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 failure
occurrence of bursting, leaking, or weeping
Note 1 to entry: See 9.1.
3.2 bursting
failure by rupture of the pipe wall with immediate loss of test liquid and drop of pressure
Note 1 to entry: See 9.1 and 9.2.1.
3.3 leaking
failure by visible loss of the pressurizing liquid through the pipe wall to an extent detectable visually and/or by a continuous drop in pressure
Note 1 to entry: See 9.1 and 9.2.1
3.4 weeping
failure by passage of the pressurizing liquid through the pipe wall to an extent detectable visually and/or electronically
Note 1 to entry: See 9.1 and 9.2.2.
4 Principle
A cut length of pipe at the required temperature is subjected to a specified internal hydrostatic pressure to cause a state of stress in the pipe wall, which depends upon the loading conditions (i.e. with or without the effects of end thrust being carried by the pipe wall). The results of tests at different end loading conditions will be different even for the same pipe. Water or air may be used as the environment outside of the test piece. The test samples are held at the test pressure until failure occurs. Typically, the time to failure is longer at lower pressures (stresses). In general, a series of tests are conducted over various failure times and the results obtained are analysed in accordance with ISO 10928 to establish a long term value. The number of tests required, the appropriate time intervals, and the time at which a value is established (time to failure) are given in the referring standard. NOTE It is assumed that the following test parameters are set by the standard making reference to this International Standard:
a) whether or not the test piece is to be loaded by the hydrostatic end thrust while under pressure (5.2);
b) free length, L, of the test piece (see 6.2);
c) number of test pieces (see 6.1);
d) test temperature and its tolerance (see 8.1);
e) if and what strain measurements are required (see 8.2);
f) external environmental fluid, i.e. water or air (see 8.3) or other environment (see Note in Clause 1);
g) internal environmental fluid, if not water or a test liquid for the purposes of 5.7 and 9.2.2 (see Note in Clause 1).
ISO 7509:2015 pdf download
