Thermoplastic pipes are widely used in the industry. They are also used for cable channels and sewage lines. To test the impact of external loads on the pipes, precise measurement according to defined standards is required. Zwick offers testing machines that are designed to test pipes with typical diameters across the entire load range. The most recent development is a customized solution that uses an extended, electromechanical Z330E testing machine (max. test load is 330 kN) for testing pipes with a diameter of up to 3.5 m.
Key test parameters include ring stiffness and ring flexibility. Ring stiffness describes the pipe's resistance against an external force that is applied radially at a constant deformation speed. This test compresses pipes of a defined length between two flat platens. This characteristic is typically measured to ISO 9969 or ASTM D2412 for thermoplastic pipes and to EN 1228 for glass fiber-reinforced pipes. In the case of profile pipes and corrugated pipes, deformation is measured by analyzing the inner diameter of the pipe to prevent flattening of the ridges. Zwick developed a special displacement transducer for this. It is permanently mounted on the testing machine and can be easily positioned inside the pipe.
There is no need to change the test setup to measure ring flexibility. It determines the ability of a pipe to withstand damage to the structure despite deformation. The test to ISO 13968 is run until the pipe fails or until deformation of 30% of the outer diameter of the pipe is reached. The test sequence is controlled by the testXpert III standard test program, making testing efficient and simple.