If the used high frequency tube mills refers to the chemical composition and mechanical properties of welded tube blanks that require certain inspection methods to be known as invisible defects; then, those defects that can be seen only by vision are called tube blanks. Overt defect.

The dominant defects of the welded tube blank of the used high frequency tube mills generally include cracked edges, broken edges, sawtooth, pitting, scratches, roll marks, dark spots, edge burrs, sickle bends, wrinkles, waves, edge warping, and points. Layers, warped skins, pinholes, sticky rolls, soft spots, rust, oxide layers, towers, loose rolls, etc. Let me introduce you to the causes of cracked edges and the effect of cracked edge billets on welded pipes.

Jagged

Sawtooth refers to the protrusion on the outer edge of the tube blank. Both cold and hot rolled tube blanks may have sawtooth, but hot-rolled tube blanks are mostly used.

Reasons for sawtooth of tube blank:

(1) During the hot rolling process, the edge of the tube blank collided with the abnormally rotating vertical rollers and side guides of the rolling mill, and was directly put into the production of welded pipes without trimming.

(2) When slitting the tube blank, the slitting blade is formed by the jumping edge; or it is caused by scratching with the separator during rewinding.

The effect of sawtooth billet on welded pipe:

(1) According to the proximity effect principle of high-frequency welding, the billet with sawtooth will approach in advance during the welding process, and "pre-welding" occurs at the tip of the tooth, causing the weld to be overburned or even burned through at the sawtooth.

(2) The larger serrations will be pressed into the lumen by the guide ring, pulling away the magnet, causing production to stop.

(3) Distortion of the guide ring and scrapped in advance.

(4) Contact welding will cause missing welding, and the contacts will be cut off and short-circuited instantaneously.

About the used high-frequency tube mills welded pipe defects (2) sawtooth introduction, and the impact of sawtooth on the quality of welded pipe, I hope it can help you.