The DSAW tube is used in the following cases:
(1) For peak regulation of pipeline, due to the uneven consumption of gas by users, frequent fluctuation of pipeline pressure and large alternating stress on steel pipe, pipeline defects have been prolonged under alternating stress. If welding seam is selected, there are high probability defects in spirally welded steel pipe, and the safe operation of pipeline will not be guaranteed.


(2) Pipelines passing through seismic fault zones or through locally high-intensity seismic zones will generate longitudinal or axial alternating stresses due to frequent geological activities in these areas. The probability of defects in spiral welding is higher than that in non-pipe welding. Under long-term stress, the occurrence probability of spiral welded pipe is much higher than that of unconventional pipe.


(3) High-level pipelines are needed inside and outside the coatings, and bias tubes should be used. The multi-weld seam of spiral pipe is generally higher than that of high-pressure pipe. The anti-corrosion effect of spiral pipe is not good because of the combination of anti-corrosion material and bare pipe as a very close pipe.


(4) For the important wear and tear of the whole project, use DSAW tube. Because future maintenance and management is more difficult than general line parts, excellent DSAW pipeline performance is used.


(5) For weak links, such as hot-ironing elbow, DSAW pipe should be used. Because of the change of direction, the internal and external force of hot-ironing elbow is larger than that of straight line. Because of the influence of various factors, the stress of hot-ironing elbow is not easy to eliminate. It is a relatively weak link in long-distance pipeline.