In terms of welding process, the welding method of spiral steel pipe and straight steel pipe is consistent, but the straight steel pipe inevitably has a lot of T-weld, so the probability of welding defects is greatly increased, and the welding residual stress at the T-weld is large, and the weld metal is often in a three-way stress state, increasing the possibility of cracking.
Spiral steel pipe and straight seam steel pipe are a kind of welded steel pipe, they are widely used in national production and construction, spiral steel pipe and straight seam steel pipe because of different production process so there are many differences, the following specific discussion of the difference between spiral steel pipe and straight seam steel pipe.
The production process of straight seam steel pipe is relatively simple, the main production process is high-frequency welding straight seam steel pipe and submerged arc welding straight seam steel pipe, straight seam pipe production efficiency is high, low cost, rapid development.
In the production of large straight seam steel pipes in the industry will use T-welding technology, that is, a short straight seam steel pipe and then butt, connected to the length of engineering needs, the probability of T-welded straight seam steel pipe defects is also greatly increased, and the welding residual stress at the T-weld is large, and the weld metal is often in a three-way stress state, increasing the possibility of cracking.
The strength of spiral steel pipe is generally higher than that of straight steel pipe, the main production process is submerged arc welding, spiral steel pipe can be produced with the same width of the billet welded pipe with different diameters, but also can be produced with a narrower billet welded pipe with larger diameters. However, compared with the straight seam pipe of the same length, the weld length is increased by 30 to 100%, and the production speed is lower. Therefore, the smaller diameter welded pipe is mostly straight seam welding, and the large diameter welded pipe is mostly spiral welding.
Moreover, according to the process regulations of submerged arc welding, each weld should have an arc starting point and an arc quenching point, but each straight seam steel pipe can not meet the conditions when welding ring joints, so there may be more welding defects at the arc quenching point. When a pipe is subjected to internal pressure, two main stresses are usually generated on the wall of the pipe, namely radial stress and axial stress.
Some people always ask, what is the difference between spiral steel pipe and straight seam steel pipe? Which would be better? Generally DN350 or more, why use spiral steel pipe instead of straight steel pipe with larger diameter? The reasons are explained now.
Specifically, spiral steel pipes and straight steel pipes are a form of weld that belongs to welded pipes. The two are generally not the same in the scope of use.
Because the weld of the spiral steel pipe is spiral, the pressure of the liquid will be distributed on each side of the pipe, enhancing the strength of the pipe.
If the straight seam steel pipe is used, the general large pipe is rolled up with steel plate and welded directly, the larger steel plate is required, which greatly increases the difficulty of production, so the larger pipe diameter will use spiral pipe.
As for which is good, because the scope of application of the two is not the same, so it is impossible to say which is better, it should be said that each has its own merits.
In general, most Nigerian groundwater projects use the ssaw spiral pipe +3lpe corrosion protection requirements, which can extend the service life of the pipeline.
