The type inspection report of PP-R pipe includes the following items: appearance, size, hydrostatic strength, ash content, melting temperature, oxidation induction time, oxidation induction time after 95℃/1000h hydrostatic test, pigment dispersion, longitudinal recovery, simple Internal pressure test in beam impact, melt mass flow rate, light transmittance and system suitability test.
Longitudinal shrinkage is an important indicator to determine the performance of thermoplastic pipe products. It reflects the stability of the pipe's longitudinal plastic changes (mainly due to thermal dimensional shrinkage) under the influence of heat. For example, for PP-R pipes, it is required that the shrinkage of the pipe length should be less than 2% under the conditions of an oven at 135°C. The smaller the value, the better.
