Weld seam cracks mostly appear in the weld seam, showing a small hair shape, most of which occur in the superficial part of the weld seam, some can be seen with the naked eye, and some need to be carefully identified or even enlarged to find.

The forming methods of straight seam steel pipes include UOE forming method, roll forming method (CFE), CE forming, etc.

General boiler tubes are mainly used to make water wall tubes, boiling water tubes, superheated steam tubes, superheated steam tubes for locomotive boilers, large and small smoke tubes and arched brick tubes.

ERW steel pipe sizing refers to the use of special pass rolls to roll welded pipes to adjust round or special-shaped pipes with irregular sizes and shapes to finished pipes with regular shapes and sizes that meet the requirements of the standard.

ERW steel pipe is based on the principle of electromagnetic induction and the skin effect, proximity effect and eddy current heating effect of the electric charge, so that the steel at the edge of the weld is locally heated to a molten state, and the butt welding is achieved through the extrusion of intergranular bonding, so as to achieve The purpose of welding.

Fine and messy molds should be pre-heated to eliminate the residual stress that occurs during machining. For fine and messy molds, if the conditions permit, try to use vacuum heating quenching and cryogenic treatment after quenching.