Welded steel pipe refers to welded steel strip or plate by means of bent round, square and other shapes and then welded into the surface of the steel pipe seam.
Welded steel blanks is used in steel sheet or strip, according to the different welding processes, it can be divided into the furnace pipe, ERW pipes and automatic arc welded pipe. Because of the different forms of welded pipe, which is divided into two and spiral welded pipe. Its shape is divided into round ends welded and shaped (square, flat, etc.) pipe.
 
Electric Fusion Welded Pipe banner - What is a welded steel pipe?
Welded steel pipe, welded steel common market in general are: double submerged arc welded pipe(DSAW pipe), high-frequency welded pipe (HFW pipe), spiral submerged arc welded pipe(SSAW pipe). Double submerged arc welded pipe is made using the molding machine has a tube opening, re-use double-sided submerged arc welding. Pipe is the use of high-frequency skin effect of high frequency current production of steel. The use of a narrow spiral submerged arc welded pipe is made of steel pipe-shaped roll, and use submerged arc welding, spiral weld, the weld compared Longitudinal length, compared with Longitudinal, it can use a specification made with a variety of large-diameter steel pipe.
Longitudinal spiral steel strength is generally higher than that, which can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. However, compared with the same length of straight seam pipe, weld length of 30 to 100%, and lower production rate. Therefore, smaller diameter pipe is mostly a straight seam welded, large diameter spiral welded pipe is mostly used.
Common surface defects of welded steel pipe
(1) layered steel
Layered wall steel tube means the cross section is divided into two floors, exposed steel surface showing the hierarchical vertical cracks. Some exhibits inside and outside surfaces of steel recessed or raised locally, layered rendering suddenly raised, dents or warping in and out of the weld.
(2) sticky scar
Pipe sticky scar refers to internal and external surfaces of the massive steel focal adhesion plaques scar.
(3) holes
Pipe through the hole refers to a local steel tube bi holes exist.
(4) open welding
Welded steel pipe opening means through long cracks in steel welds or partial showing of.
(5) Local lap welding
Welded steel pipe refers to a partial outer surface of the steel pipe presents a partial arc weld.
(6) Welding ditch
Pipe welding groove is the outer surface of the steel pipe occurs through a long groove weld.
(7) the collapse of welding
Welded steel pipe collapse refers to the outer surface of the weld metal skeletons showing through a long trench, where the surface of the corresponding convex edges.
(8) pipe joints dislocation
Steel tube joint dislocation refers to the steel pipe weld, occurred the phenomenon of staggered up and down.
The advantages and disadvantages of welded steel pipe
The average wall thickness of the tube light table table high (steel exterior appearance of steel grade resolution, brightness) can be arbitrary length. Thus, it showed its economy and aesthetics in accuracy, the use of low-pressure fluid.
Welded steel pipe production process is simple, high production efficiency, low cost, to carry out faster. Spiral Welded Longitudinal higher than normal, can narrow the billet production of large diameter pipe, you can use the differences diameter pipe billet production of the same width. What, then with the same length of straight pipe joints compared weld length add 30 to 100%, and lower production rate. Thus, most of the smaller diameter pipe straight seam welded, large diameter spiral welded pipe for the most.
Classification of welded steel pipe
1, High frequency welded steel pipe features: tubular good, uniform thickness, internal and external burrs produced by the welding tool calibrating the appropriate online through strict control of non-destructive testing of weld quality, high degree of automation, low production costs. But relatively thin wall thickness, diameter is relatively small, usually no more than a wall thickness of 12mm, diameter generally does not exceed 610mm, particularly suitable for the production of steel tube truss structure.
2, LSAW pipe features: welding under static conditions, high weld quality, short welds, the probability is very small defects. By expanding full-length steel tubular good, precise size, wide range of pipe wall thickness and diameter range, the diameter range up 406-1829mm, wall thickness range up 6.0-60mm, high degree of automation, Compared to seamless steel, it is lower production costs, for buildings, bridges, dams, offshore platforms and other steel bearing with columns, large span structures as well as wind and seismic requirements for electrical tower mast s