(1) Pipeline peak load demand due to the user's natural gas consumption is very uneven, frequent pipeline pressure fluctuations, alternating stress steel to withstand large pipe will expand the defects in alternating stress, if there is more choice , The probability of welding defects high, spiral welded pipe, the safe operation of the pipeline will not be guaranteed.
(2) Pipeline crossing the seismic fault or local high intensity zone will generate vertical or axial alternating stress due to the frequent geological activities in these areas. Helical welds have a much higher probability of being flawed than straight-welded tubes. In long-term pressures, helical welded pipe is much more likely to fracture than an accident, and therefore LSAW pipes should be used in these areas.
(3) Straight seam submerged arc welded pipe should be adopted for the pipe with high internal and external coating requirements. Spiral submerged arc welded pipe weld seam weld than LSAW pipe higher than normal, when the steel pipe inside and outside anti-corrosion, anti-corrosion materials and smooth pipe with a combination of not straight seam submerged arc welding, anti-corrosion effect of poor
LSAW steel pipe .
(4) The important wear across the project, the use of LSAW pipe. Due to the difficulty of maintaining and managing in the future than usual straight sections, therefore, the use of excellent performance LSAW pipes is especially necessary.
(5) Pipe defects such as hot simmer pipe should be used LSAW pipe. Hot simmer bends due to changes in direction, they come into contact with the internal and external forces than the straight line is generally larger, due to various factors in the brewing process, the elimination of stress is not easy, is in a weak link, long-distance pipeline, Integral performance of LSAW pipe can make up for these deficiencies.
