ISO 9967:2016 Thermoplastics pipes — Determination of creep ratio

This standard specifies a method for determining the creep ratio of thermoplastics pipes having a circular cross-section.

ISO 9967 Creep Ratio Test Machine for Thermoplastic Pipes 

The ISO 9967 test procedure begins by preparing a ring-shaped specimen from a thermoplastic pipe. The ring is typically cut to a length equal to the pipe’s outer diameter and must be free of visible defects. Before testing, the sample is conditioned, usually at 23°C for at least 24 hours. During the test, the specimen is placed vertically between two flat, parallel plates in a compression testing machine. A constant external force is applied to the ring to compress it until a deformation equal to 3% of its mean diameter is reached. This loading should occur gradually, typically within one minute. The test apparatus must maintain this compressive load over an extended period, most commonly 10,000 hours, under controlled environmental conditions. The deformation of the ring is measured at defined intervals during the test using a precise displacement measurement device. Initial and long-term measurements are used to calculate the creep ratio. This ratio quantifies how much the ring deforms over time under constant load, which indicates the material's long-term behavior and suitability for buried, non-pressure pipe applications. Accurate time tracking and temperature control are critical throughout the process to ensure valid results. The test concludes by comparing the deformation at 30 minutes and at the final time point to calculate the creep ratio according to the formula provided in the ISO 9967 standard.

Test procedures:

1.     According the pipe diameter: inner diameter size choose the pre-load force（di small 0.1m  f0=7.5N,

If di large than 0.1m，calculate as below:  f0=56.3N

2.     Confirm the loading force F:

The pipe inner diameter is di. Then the deformation will be 0.015*di = A(mm).

Open the software, install the sample, and adjust the deformation measuring device to make full contact with the inner wall and reset it to zero,

Choose 5mm/min (recommended) to compress the sample to a force of 7.5N or 56.3N, stop, and reset the deformation and displacement to zero. Then select a speed of 2Amm/min, compress the specimen, and record the force value Fa when the deformation reaches A. Use this value as the full load for the creep experiment.

Beijing United Test Co.,Ltd. export@unitedtest.com offer the ISO 9967 Creep Ratio Test Machine for Thermoplastic Pipes . Contact us now : export@unitedtest.com, unitedtest@hotmail.com