Since the 1930s, with the rapid development of high quality of strip steel rolling production and the progress of welding and inspection technology to improve the weld quality constantly, increasing varieties of welded steel pipe specifications. Welded steel pipe seamless steel tube of low cost, high production efficiency according to different welding methods of the welded steel pipe and classification of welded steel pipe, which is composed of electric arc welding tube, high frequency or low frequency electric resistance welded pipe and gas welding tube, furnace welding pipe, bondi pipe and so on. Welded steel pipe is used for oil drilling and machinery manufacturing and so on.
Furnace welded pipe can be used for water gas pipe and so on. The big straight seam welded pipe is used in high pressure oil and gas transportation and so on. Classification of welded steel pipe is used for oil and gas transportation, pipe pile and so on. According to the weld shape classification, the welded steel pipe consists of straight seam welded pipe and spiral welded pipe. The production process of straight seam welded pipe is simple with high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe, which is using a narrow billet production of larger diameter welded steel pipe. You can also use the same width of billet in the production of different pipe diameter welded pipe. But compared with the same length of straight seam pipe, weld length by 30 ~ 100%, and the production speed is low. As a result, a small diameter welded pipe are mostly with straight seam welding, large diameter welded pipe for the most part adopts spiral welded.
Spiral seam welded steel pipe can be divided into automatic submerged arc welding steel tube and high frequency welded steel pipe. The spiral seam automatic submerged arc welding steel pipe according to the medium pressure level is divided into two classes a and b tube. Class a tube with plain carbon steel Q235, Q235F. And they generally low alloy structural steel, 16 mn welded, tube with Q235, Q235F, Q195 steel welded, used as a low pressure of fluid conveying pipes. High frequency welded steel pipe spiral seam high frequency welded steel pipe, spiral seam is not unified product standards, generally uses ordinary carbon steel Q235, Q235F steel manufacturing and so on.
Corrosion performance of the welded steel pipe containing Ni when in acidic environment corrosion resistance is strong. In the environment of the containing sulfuric acid or hydrochloric acid, the higher the content of Ni in welded steel pipe, corrosion resistance stronger. In the general environment, can add Cr in the steel pipe which can prevent erosion phenomenon. Steel strip edge condition is another important cause of the wrong side.