Seamless steel tube, the very important role in the national economy, is a kind of economic cross-section steel. It is widely applied in many departments such as petroleum, chemical industry, boiler, power stations, ships, machinery manufacturing, automobile, aviation, aerospace, energy, geology, architecture and military industry and so on.

2. Classification of Seamless Steel Pipe

(1)According to the cross-section shape: circular cross-section pipe, special-shaped cross-section pipe.

(2)According to the material: carbon steel pipe, alloy steel pipe, stainless steel pipe, composite pipe.

(3)According to the connection ways: threaded pipe, welded pipe.

(4)According to the mode of production: hot rolling (squeeze, top, expand), cold rolling (pull out).

(5)According to utility: boiler tube, OCTG pipe, pipeline, structural pipe, chemical fertilizer pipe.

3. The quality requirements of seamless steel pipe

(1) The steel chemical composition: the chemical composition of steel is one of the most main factors that affect the performance of seamless steel tube, and it is also the main basis that formulates process parameters about rolled tube and heat treatment process of steel tube.

A. Alloy elements: put them according to the purpose

B. Residual elements: put them and properly control when steeling

C. The harmful elements: strictly control (As, Sn, Sb, Bi, Pb), gas (N, H, O)