Seamless steel pipe is made of ordinary and high-quality carbon structural steel (Q2 15-A ~ Q275-A and 10 ~ 50 steel) and low-alloy steel (09MnV, 16Mn, etc.). ), alloy steel, stainless steel and acid-resistant steel.

Welded pipe is made of steel plate or strip steel by crimping.

Difference two, different uses

Seamless steel pipes are mainly used as drilling pipes in petroleum geology, cracking pipes in petrochemical industry, boiler tubes, bearing pipes and high-precision structural steel pipes for automobiles, tractors and aviation.

Welded pipes are widely used in tap water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation and urban construction.

Welded pipes are used for liquid transportation, water supply and drainage. Used for gas transportation: gas, steam, liquefied petroleum gas; Used for structure: used for piling pipes and bridges; Pipes for docks, roads, building structures, etc.

Extended data:

Development course:

Since 1930s, with the rapid development of high-quality strip continuous rolling production and the progress of welding and inspection technology, the weld quality has been continuously improved, and the varieties and specifications of welded steel pipes have been continuously increased, replacing seamless steel pipes in more and more fields.

Welded steel pipes are divided into straight welded pipes and spiral welded pipes according to the weld forms. The production process of straight 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 welded pipe. Welded pipes with larger diameters can be produced from narrow blanks, and welded pipes with different diameters can also be produced from blanks with the same width.

Compared with the straight seam pipe with the same length, the weld length is increased by 30~ 100%, and the production speed is lower. Therefore, straight seam welding is mostly used for welded pipes with smaller diameter, and spiral welding is mostly used for welded pipes with larger diameter.

Baidu encyclopedia-seamless steel tube

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