Plastic piping systems – Glass-reinforced thermoset plastic tubes (GRP) – Test methods for the determination of initial apparent tensile strength.
ISO 8521 specifies six test methods for the determination of the initial circumferential strength of the tensile wall per unit length of glass-reinforced thermoset plastic (GRP) pipes.
NOTE Another term commonly used for “circumferential tensile strength” is “rim tensile strength” and the two expressions can be used interchangeably.
The rupture test (method A) is suitable for all types and sizes of pipes. The reference method is considered. However, all ISO 8521 methods have equal validity. If the correlation of any of the methods B to F can be established by a comparative test program, then that method can be considered as the reference method. The split-disc test (method B) may not be suitable for pipes with helically wound reinforcement layers. The strip test (method C), the modified strip test (method D) and the restricted strip test (method E) are suitable for pipes with a nominal size of DN 500 and above. The toothed plate test (method F) is intended primarily for use with helically wound pipes of nominal size greater than DN 500 with a winding angle other than approximately 90 °.