PVC-M pipe

1. Excellent impact resistance performance

The flexibility of PVC-M pipes has been significantly enhanced, and the good toughness has improved the impact resistance of the pipes, effectively resisting external impacts during installation and transportation, and enhancing the ability of the pipes to resist external damage.

Taking DN200mm pipe as an example, in the drop hammer impact test at 0 ℃, the impact height of PVC-U pipe and PVC-M is 2 meters, but the impact hammer mass of PVC-M is 10kg, and the impact hammer mass of PVC-U is only 2kg. Obviously, the impact energy borne by PVC-M is much higher than that of PVC-U pipe, indicating that the toughness of PVC-M is much higher than that of ordinary PVC-U pipe.

The 22 ℃ and 20m rapid impact test for PVC-M pipes is more convincing. The standard requires the test to be conducted at 22 ℃, with a hammer mass of 3-30kg (taking dn200mm as an example, the hammer mass reaches 20kg) and an impact height of 20m. The test requires that all samples do not undergo brittle failure to be qualified, while PVC-U pipes do not have this requirement. After systematic comparative testing, it was found that PVC-M pipes were all subjected to toughness failure after impact, with a small pit punched out on the outer wall of the pipe, and the pipe body was not damaged; But under the same conditions of testing, PVC-U pipes will fracture after being impacted.

Although throwing, dropping, rolling, and dragging of pipes are strictly prohibited in the technical regulations for plastic pipeline construction, pipes are inevitably subjected to external impact during actual loading, unloading, transportation, and installation processes. PVC-M can effectively resist external impact and ensure pipeline safety.

2. Excellent anti cracking performance and ability to withstand point loads

In practice, pipes are inevitably damaged or subjected to stress concentration due to poor laying. Pipes with poor crack resistance are prone to leakage, rupture, and brittle failure due to crack propagation. Experience has shown that the majority of accidents in PVC-U pipelines in the past were "low stress brittle fracture", which means poor resistance to stress cracking.

The resistance to point load and environmental stress cracking of PVC-M is significantly improved. If scratches are accidentally caused on the surface of the pipe, they will not affect the use of the pipe. To verify the stress cracking resistance of PVC-M, a hydraulic test was specifically developed for notched pipes. The cut pipe test is to determine the degree to which the pressure bearing capacity and service life of the pipe are affected after the surface of the pipe is damaged. Firstly, a cut must be made on the surface of the pipe, with a depth of 10% of the pipe wall thickness. Then, a test must be conducted according to the standard for withstanding internal pressure. Only when the test is qualified (without rupture) can the quality of the pipe be considered qualified. This test is unique to impact resistant pipes (PVC-M) and is based on the principle of ISO13479 "Slow Crack Growth Incision Pipe Test" required for PE pipes. PVC-U pipes do not require this test.

The hydraulic test results of the cut pipe indicate that PVC-M has strong resistance to point load, stress cracking, and crack growth. PVC-M (with incisions) has high reliability and long-term strength that is not affected; PVC-U (with incisions) has a significant decrease in long-term strength and low reliability. Due to the reduced sensitivity of PVC-M pipes to cuts, safety hazards have been eliminated, ensuring the long-term, safe, and reliable operation of the pipeline.