ISO 8521-2020 pdf free.Glass-reinforced thermosettingplastic (GRP) pipes — Test methodsfor the determination of the initialcircumferential tensile wall strength.
This document specifies six test methods for the determination of the initial circumferential tensilewall strength per unit of length of glass-reinforced thermosetting plastics (GRP) pipes.
NOTE Another commonly used term for “circumferential tensile strength” is “hoop tensile strength” and thetwo expressions can be used interchangeably.
The burst test(method A)issuitable for all types and sizes of pipes.Iltis considered thereference method.However, all the methods in this document have equal validity. If correlation of any of the methods Bto F can be established by a comparative test programme, then that method can be considered as thereference method.
The split disc test(method B) is not always suitable for pipes with helically wound reinforcing layers.The strip test (method C), the modified strip test (method D) and the restrained strip test (method E)are suitable for pipes with a nominal size of DN 500 and greater.
The notched plate test (method F) is primarily intended for use with helically wound pipes of nominalsize greater than DN 500 with a winding angle other than approximately 90°.
Results from one method are not necessarily equal to the results derived from any of the alternativemethods.
lf required, the initial circumferential tensile modulus can be determined by method A.
There are no normative references in this document.For the purposes of this document, the following terms and definitions apply.
Hydrostatic pressurising system, capable, for pipes up to DN 500, of causing failure of the testpiece between 1 min and 3 min after commencing the pressurization.For some nominal sizes greater than DN 500, the duration of the test will, for practical equipmentreasons, need to be increased. Where increasing the testing time results in lower burst pressures,thisshall be evaluated by comparing results of different test durations.
The pressurising system shall prevent air from entering the test piece during pressurization to failure.
Pressure measuring device, calibrated within an accuracy of 2,0 %.End sealing devices for the test pieces, capable of inducing in the test piece, during the test, amainly uniaxial state of stress in the circumferential direction in the test piece (see Figure 1).Dimension measurement devices,calibrated within an accuracy of 0,1 mm.Test piece support, if needed, to minimize deformation due to the weight of the test piece andits contents.
Strain measurement, if circumferential tensile modulus of the pipe wall is to be determined,strain gauges of the foil type, single element suitable for the anticipated strain level and of a lengthappropriate for the pipe diameter.ISO 8521 pdf download.