Fundamentally speaking, spiral steel pipe or straight seam steel pipe is a kind of welded steel pipe. Because of their superior performance, these two steel pipes are widely used in various projects. Of course, because the two production processes are different, in actual There is still a big difference in the use process, which directly leads to a big difference in the scope of use of the two steel pipes.
Compared with spiral steel pipe, the production process of straight seam steel pipe is much simpler. The production process of straight seam steel pipe is mainly divided into two types, one is high-frequency welded straight seam steel pipe, and the other is submerged arc welded straight seam steel pipe. It is precisely because of these characteristics that the production process of the straight seam steel pipe is simple, the production efficiency of the straight seam steel pipe is very high, the cost is low, and the speed of development is also very rapid.
The production of large-diameter longitudinal seam steel pipes in the industry will adopt T-welding technology, that is, the short sections of the longitudinal seam steel pipes will be spliced into a length that meets the engineering requirements, which greatly increases the probability of T-welding defects of the longitudinal seam steel pipes. In addition, the welding residual stress at the T-shaped weld is relatively large. The weld metal tends to produce a stress effect, which increases the possibility of cracks.
Compared with straight seam steel pipes, spiral steel pipes have certain advantages in strength. The main process for producing spiral steel pipes is submerged arc welding. Spiral steel pipes can be used to produce welded pipes of different pipe diameters from blanks of the same width. It can also be used to produce welded pipes with larger diameters from narrower blanks. However, compared with the straight seam pipe of the same length, the length of the welded pipe is increased by 30-100%. Because of the above reasons, the production speed of the spiral steel pipe is very slow. Therefore, straight seam welding is mainly used for small diameter welded pipes. The spiral welding is mainly used for large diameter welded pipes.
In addition, according to the submerged arc welding process specification, each weld should have an arc ignition point and an arc extinguishing point. However, each straight seam steel pipe cannot meet this condition when welding the circumferential seam. Therefore, there may be more welding defects at the arc extinguishing point. When the pipe is subjected to internal pressure, two principal stresses are usually generated on the pipe wall, namely radial stress and axial stress.
Some people always ask, what is the difference between spiral steel pipe and straight seam steel pipe? Which kind of steel pipe is better to use in construction, in fact, it is unscientific to answer whether it is a straight seam steel pipe or a spiral steel pipe.
Specifically, both spiral steel pipes and straight seam steel pipes are welded welded pipes. The two are usually used in different fields.
Since the weld is spiral, the liquid pressure on the spiral steel pipe will be distributed on each side of the pipe. To enhance the strength of the pipeline.
If a straight seam steel pipe is used, the general large pipe is rolled up with steel plate and welded directly. A larger steel plate is required. This greatly increases the manufacturing difficulty. Therefore, spiral pipes will be used for larger pipe diameters.