Performance advantages of engineering line pipe
Linepipes are mainly used to transport oil and natural gas pipelines. What advantages does it have?
1.Corrosion resistant. Polyethylene is an inert material that, in addition to a few strong oxidants, is resistant to attack by a variety of chemical media. No electrochemical corrosion, no need anti-corrosion layer.
2.No leakage. The polyethylene pipe mainly adopts the fusion connection (hot-melt connection or electro-fusion connection), which essentially ensures the identity of the interface material and structure and the pipe body itself, and realizes the integration of the joint and the pipe material. The test confirmed that the tensile strength and bursting strength of the interface are higher than the pipe body, which can effectively resist the hoop stress and axial tensile stress generated by the internal pressure. Therefore, there is no risk of leakage due to joint distortion compared to rubber ring joints or other mechanical joints.
3.High toughness. Polyethylene pipe is a kind of high toughness pipe, its elongation at break generally exceeds 50%, and it has strong adaptability to uneven settlement of pipe foundation. It is also a pipe with excellent seismic performance. In the 1999 Kobe earthquake in Japan, polyethylene gas pipes and water pipes were the only pipe systems that were spared. Because of this, after the earthquake in Japan, the use of PE pipes in the gas field was greatly promoted.
4.Polyethylene pipe has excellent flexibility. The flexibility of polyethylene is an important property that greatly enhances the value of this material for pipeline engineering. The flexibility of the polyethylene allows the polyethylene tube to be coiled and supplied over a longer length without the need for various connecting fittings. For non-grooving construction, the direction of the polyethylene pipe is easy to change according to the requirements of the construction method; the flexibility of the polyethylene material allows it to change the shape of the pipe before construction, and restore the original size and dimension after inserting the old pipe.
5.Polyethylene pipes have good resistance to scratches. With unslotted construction techniques, scratches are unavoidable, whether it is repairing or renewing new or old pipes. Scratches cause stress concentration in the material, causing damage to the pipe. The ability of the pipe to resist scratches is closely related to the slow crack growth (SCG) behavior of the pipe. Studies have shown that PE80 grade polyethylene pipes have good resistance to SCG and scratch resistance. PE100 polyethylene pipe material provides superior resistance to scratches.
6.Good rapid crack propagation resistance. Internationally, a lot of fruitful research work has been done on the rapid crack propagation of plastic pipes and special polyethylene gas pipes. The results show that in the commonly used plastic pipes, the ability of polyethylene to resist the rapid transmission of cracks is among the best. 5MNm-, The KD of PE100 is 2.9MNm- 3/ 2. The lower the temperature, the larger the pipe diameter and wall thickness, the higher the working pressure, and the greater the risk of rapid cracking of the plastic pipe. Therefore, polyethylene pipes, especially PE100 pipes, are more suitable for large diameter pipes. At present, foreign polyethylene gas pipe standards (ISO4437-1997 and EN 1555) have included rapid crack initiation resistance (RPP) in the standard.
7.Polyethylene pipe has a long service life of more than 50 years. This is determined by the long-term hydrostatic design basis value (HDB) of polyethylene pipe hoop tensile strength, which has been confirmed by international standards.