The welding process of submerged arc LSAW steel pipe is to connect the welding wire and steel plate by filling the weld to achieve the welding of LSAW steel pipe, while high frequency LSAW steel pipe uses the skin effect of high frequency current to melt the edge of the weld of the steel plate quickly, so that the weld will be fused together under the pressure of the external force, and the welding will be achieved.

In terms of moulding, double-sided submerged arc LSAW steel pipe adopts JCOE moulding, which is cold-formed by stamping the steel plate one by one through the press, while high-frequency LSAW steel pipe adopts the moulding process in which the FXH multi-rolls are gradually turned into round shapes.

In addition, there are obvious differences between submerged arc LSA steel pipe and HF LSA steel pipe in terms of production range, materials used, industries used and appearance.

The production range of submerged arc steel pipe is from 325mm to 1420mm in diameter, and the wall thickness is from 7.5mm to 80mm, which can produce LSAW steel pipe of any material, and conforms to 9711 and API standards; while the production range of HF steel pipe is from 15mm to 660mm in diameter, and the wall thickness is from 0.1mm to 18mm, which is mainly used to produce pipeline steel material, and conforms to 9711 and API standards.

Submerged arc steel pipe is suitable for oil and gas pipelines, steel pipe piling, steel structure and submarine steel pipe, etc.; high frequency steel pipe is suitable for grid structure pipe, small diameter fluid steel pipe, electric wire pipe, foundation light structure and bottom pressure fluid steel pipe, etc.

Appearance, high-frequency LSAW steel pipe appearance is smooth, no welding seam residual height, greenish grey; while submerged arc LSAW steel pipe body has obvious bar type indentation and steel plate surface slight oxides off traces, the appearance and high-frequency LSAW steel pipe has obvious difference.

In terms of appearance, HFW steel pipes have a smooth and seamless outer surface without any weld seam excess height, presenting a bluish-gray color. On the other hand, SAW steel pipes exhibit distinct strip-shaped indentations on the pipe body and slight oxidation residue marks on the steel plate surface, making their appearance significantly different from HFW steel pipes.

In conclusion, despite both SAW and HFW steel pipes being essential in the steel industry, their differences in welding processes, forming methods, production ranges, materials used, application fields, and appearances highlight the unique characteristics and suitability for different industrial applications.