Rolling seamless steel pipes should focus on operating in strict accordance with the construction specifications and technical requirements related to indirect technology, rather than processing and repairing after cracks.For metals of special materials and new steel grades, tests should be carried out before rolling to find a more practical probe technology for review to ensure the welding quality.

DIN 2391 standard specifies the Seamless steel tubes used for Mechanical and Automobile.The main products of steel / steel grade: DIN2391-1(ST35, ST45, ST52).

Trimming is concentrated before the pipeline leaves the factory. In order to ensure the welding quality, a comprehensive inspection and correction are carried out before welding, so that the end face, bevel angle, blunt edge and roundness of the pipe meet the requirements of the size of the butt joint.When individual steel pipes need to be beveled on site, gas welding is used to cut, remove the slag, and then use a grinding wheel to smooth it.The corresponding operation procedure is: check the size of the interface joint → clear the cavity → determine and adjust the staggered position of the longitudinal weld of the steel pipe → find the straight line for the first time → adjust the gap size of the counterpart → level the pipe line → find the straight line of the pipeline → spot welding.

The porosity of the large-diameter spiral pipe seam not only affects the fineness of the welding seam of the pipeline, causing leakage of the pipeline, but also becomes the induction point of corrosion, which seriously reduces the strength and resistance of the welding seam.The bubbles in the spiral steel pipe mostly occur in the center of the weld bead, the main reason is that the hydrogen is still hidden inside the weld metal in the form of bubbles.At the same time, the moisture, dirt, oxide scale and iron filings in the flux, the welding composition and covering thickness, the surface quality of the steel plate and the treatment of the steel plate side plate, the welding technology and the steel pipe forming technology may induce the generation of pores on the spiral steel pipe.

The control measures for the welding quality of ssaw steel pipes are mainly pre-control and in-process control.

Color penetrant inspection of welds is one of the effective methods to inspect the surface defects of welded joints. It can effectively and quickly check for defects in the welding of erw steel pipes.Compared with magnetic particle inspection of welds, it has the advantage that it is not limited to ferromagnetic materials, and its application range can be extended to non-magnetic materials such as austenitic stainless steel and alloys.