s are used in the following cases:
(1) for the pipeline peak adjustment, because the gas consumption of the users is very uneven, the pipe pressure fluctuates frequently, the steel pipe bears greater alternating stress, and the pipe defects are extended under the action of alternating stress. If the weld is used, the defect probability of the spiral welded pipe is high, and the safety operation of the pipe will not be guaranteed.
(2) pipelines pass through seismic fault zones or through local high intensity seismic regions. Due to frequent geological activities in these sections, pipelines will produce longitudinal or axial alternating stress. In spiral welding, the probability of defect is higher than that of DSAW tube. Under long-term pressure, the possibility of spiral welded pipe is much higher than that of DSAW pipe.
(3) inside and outside the coating needs top management line. DSAW pipe should be used. The spiral pipe is much more, the weld is generally higher than the double helix pipe, inside and outside the steel pipe anticorrosion, the anticorrosive material and the bare pipe combination bare pipe as the closed tube, the anticorrosion effect is not good.
(4) DSAW pipes are used for important wear and tear of the whole project. Because future maintenance and management are more difficult than normal circuit segments, DSAW tubes with excellent performance are used.
(5) DSAW pipe
s should be used for weak links, such as hot bending pipes. Because of the change in the direction of the heat simmering elbow, the internal and external force is larger than that of the general line. The pressure is not easy to eliminate in the process of impact and simmering of various factors, and it is a relatively weak link in the long distance pipeline.