Nitriding treatment refers to the chemical heat treatment process in which nitrogen atoms infiltrate the surface of the steel pipe in a certain medium at a certain temperature. The common ones include liquid nitriding, gas nitriding, and ion nitriding. The purpose is to improve the surface hardness and wear resistance of the steel pipe. Improve fatigue strength, corrosion resistance, etc.

The magnetism of the seamless tube is due to the magnetism of martensite or ferrite, and a small amount of martensite or ferrite will be formed during component segregation or improper heat treatment during movement. In this way, there will be weak magnetism in the seamless tube. At this time, it is necessary to demagnetize the seamless steel pipe.

There are three main connection methods when connecting galvanized pipes, namely wire type, welding type and rolling groove type. 1. If the thread type method is used, the thread buckle cannot be in complete contact with the pipe hoop of the steel pipe, otherwise it is likely to become loose. Before connecting, it is necessary to measure whether the wall thickness of the steel pipe can reach the standard thickness of the thread. If the thread of the steel pipe does not match the thread of the pipe hoop and cannot be connected, the pipe hoop should be replaced or the equipment should be adjusted to re-thread the thread.

In order to improve the anti-corrosion conditions of the medium, the following two methods can be used.①Remove harmful components in the medium. ②Add corrosion inhibitor. Corrosion inhibitor is a substance that can slow down the corrosion rate. Adding corrosion inhibitor is a common and effective anti-corrosion measure. Different corrosion inhibitors are only effective in certain environments.

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.