Submerged arc welding technology is the welding process of SSAW steel pipe and LSAW steel pipe. During the welding process, in addition to insufficient penetration, burn-through and poor formation caused by improper welding process parameters, there will also be pores, slag inclusions, cracks, etc. Defects. This article mainly introduces the main reasons and preventive measures for porosity in submerged arc welding seams.

External fold is a common outer surface defect of seamless steel pipe, which is characterized by helical layered folds on the outer surface of the steel pipe. The outward folding of seamless steel pipes is mostly caused by the defects of the billet. During the rolling process of the steel pipe, because the billet is subjected to frequent alternating tensile stress, the stress state is relatively bad, and it is easy to expand the defects of the billet. The corresponding inner surface defect is the inward fold of the seamless steel pipe, which is characterized by straight line or helical or semi-spiral zigzag defects on the inner surface of the steel pipe.

During the rolling process of seamless steel pipes, due to the influence of the stability of the machine and peripheral equipment and the uncertainty factors in the production process, the product dimensions often exceed the tolerance range specified in the product standard. The situations are as follows:

Grinding of thick-walled seamless nozzle: After cutting, use an angle grinder to grind the plastic layer of the nozzle. Its purpose is to prevent the plastic layer from melting or even burning during the flange welding process, damaging the pipe, and grinding the nozzle plastic layer with an angle grinder.

A flange is a disc-shaped part that is most common in plumbing engineering.It is the part that connects the pipes to the pipes. Connect to the pipe end. There are holes on the flanges for bolts to connect the two flanges tightly. The flanges are sealed with gaskets.

The medium used for quenching and cooling of seamless steel pipes is called quenching cooling medium (or quenching medium). The ideal quenching medium should have the condition that the steel can be quenched into martensite without causing too much quenching stress.The commonly used quenching media for quenching and cooling of seamless pipes are water, aqueous solution, mineral oil, molten salt, molten alkali, etc.