Instability spiral steel pipe expansion and crack arrest

Crack instability of disaster research and control. Pair of spiral steel long pipeline is very important. Pressure vessels and factory spiral piping network once the crack, all at once would have been destroyed, it is because the sake of these components is too short, so for them, mainly controlled study initiation and expansion of its instability research seems to crack arrest is pointless. Spiral steel pipe for long-distance pipeline situation is very different, although the initiation of long-distance pipelines for spiral pipe is also very important, a lot of people at home and abroad have done a lot of work, but more important is starting soon unstable propagation of crack after crack can get an early crack than to prevent long break, causing serious damage.

Initiation of the word, in the spiral steel pipe is a long-distance large diameter pipe and spiral steel pipe weld defects, including transport and construction process of the surface damage caused (such as indentations and scratches, etc.) in the pressure test procedure after a period of steady expansion, or in the operating process due to stress corrosion and fatigue fracture propagation (due to pressure fluctuations) and other reasons, the formation - "after the expansion phase stability, resulting in leakage through
cracks in terms of the medium for compression container to control the initiation, is to make the entire life process defects will not reach the critical crack length, the unstable growth will not happen for long-distance pipeline, it is very difficult to do that in fact the current domestic were done outside, this is because spiral pipe some up to hundreds of kilometers and even dry I kilometers long welds, weld too, plus the construction and damage caused during transport, so that string machine undetected surge addition long pipeline is buried, and often is continuously conveyed, in fact, can not be checked throughout the period, due to "leak-before-crack" criteria and regular
observation of the defect etc. Diao; possible so that we can only focus on the spiral pipe crack instability on the crack arrest.