Features and causes of 8 defects of seamless steel pipe:folding, crack, scratches, pit, pitted floor, spots, warped pores and skin, scar.

If there are some defects in the seamless steel pipe, it can undoubtedly have a fatal influence on the standard of our products. So the way to avoid these defects? Then you definitely need to grasp the reasons for these defects. Permanent Steel Manufacturing Co. Should you loved this information and you wish to receive more info concerning steel rod (diigo.com) assure visit the website. ,Ltd will work with you to discuss the particular causes for the eight defects of seamless steel pipes:

1. Seamless steel pipe-folding

It is a linear or spiral, continuous or discontinuous state that exists on the outer or interior floor of seamless steel pipe. The primary motive for the folding is poor quality of the pipe materials, folding itself, or inclusions, severe scratches and cracks on the floor, edges and corners in the grinding place, and folding after drawing. In an effort to keep away from folding, steel rod the quality of the pipe materials must be improved and attention must be paid to inspection and grinding.

2. Seamless steel pipe-crack

Refers to the small cracks on the internal and outer surfaces of the seamless steel pipe that are distributed in a straight line or a spiral, with a depth of 1 mm or extra, continuous and discontinuous. According to the evaluation of Permanent Steel Manufacturing Co., Ltd, the cause is: the recent-rolled tube clean has subcutaneous bubbles and subcutaneous inclusions, and there are cracks or deep pits on the steel pipe before drawing. During the new rolling or chilly drawing processes Longitudinal scratches or scratches occurred throughout the operation. Preventing the formation of cracks also lies in improving the standard of the tube clean and strengthening the inspection and grinding of the tube materials. At the same time, pitting, scratches and scratches should be prevented throughout the cold drawing production process.

3. Seamless steel pipe-scratches

The characteristic of the defect is that there are longitudinally linear scratches of varying lengths on the internal and outer surfaces of the seamless pipe. Most of them are groove-formed, however they may even be raised stripes. The main reason for the scratches (chopping) is: there are inside markings on the pipe material, which can’t be eliminated throughout drawing, the iron oxide film remains on the steel pipe and the mold sticks to the steel, and the power and hardness of the mold are insufficient or uneven. Fragmentation and wear occur, the hammer head is defective, and the sharp edges and corners of the hammer head transition half harm the mold. So as to prevent scratches and scratches, the standard of each preparation course of before drawing should be improved, and molds with high energy and hardness and good smoothness needs to be used.

4. Seamless steel pipe-pit

That is certainly one of the commonest surface defects of seamless pipes. Local depressions with totally different areas are distributed on the floor of the steel pipe. Some of them are periodic and a few are irregular. The pits are brought on by iron oxide scale or different hard dirt pressed into the surface of the steel pipe through the drawing or straightening process, or the peeling of the original peeling on the floor of the steel pipe. Shandong Jute Pipe Industry pointed out that the measures to stop pits are to carefully inspect the pipe materials and take away defects resembling warping, keep the work site, tools and lubricants clear, and prevent oxide scale and dirt from falling on the surface of the steel pipe.

When there are clean or sharp spiral marks on the outer surface of the seamless steel pipe, the straightening machine should be checked. Due to the incorrect position and steel rod angle of the straightening roller, the steel pipe rubbed the shoulders on the sting of the straightening roller during straightening. There are worn grooves on the straightening roller, and both ends of the steel pipe may appear on the outer floor of the steel pipe. Pits.

5. Seamless steel pipe-pitted surface

It’s characterized by small pits in the type of pieces and dots on the surface of the steel pipe. The primary motive for the pitting floor is pitting corrosion throughout pickling. After annealing, the oxide scale is simply too thick and straightened and pressed into the floor of the steel pipe to kind a pitted surface; the steel pipe is saved in a humid setting, and even pitted rust occurs after water enters. After eradicating the rust spots Form pitted surface.

6. Seamless steel pipe-spots

Since seamless steel pipes are in touch with water (or water vapor) throughout processing or storage and aren’t treated in time (akin to drying), the traces left by water evaporation are referred to as water spots, similar to lengthy contact with water or corrosive water Rust spots are formed when the substance is Water spots typically have no depth, and rust spots usually corrode the surface of the steel pipe, and there’ll nonetheless be pitted surfaces after elimination.

7. Seamless steel pipe-warped pores and skin

It’s characterized in that the internal and outer surfaces of the seamless steel pipe are partially separated from the steel substrate, and the individual items are lumpy, discontinuous, rooted or not rooted on the pipe wall, however cannot peel off naturally. The reasons are poor steel high quality, the existence of subcutaneous bubbles, which are uncovered after chilly drawing; the warping produced throughout sizzling rolling will not be eliminated on the tube billet to cold drawing; the original deep and angular transverse pits on the steel tube After drawing, it varieties a warped skin.

8. Seamless steel pipe-scar

The interior and outer surfaces of the steel pipe were not eliminated in time on account of defects corresponding to folding and warping. In the subsequent processing, skinny slices that could not be separated from the metal substrate have been formed. A few of them were lumpy, discontinuous, and rooted or not rooted on the pipe wall, however they couldn’t peel off naturally. , Called scarring. Surface defects should be checked and eliminated in time to eradicate scars.

Tips: ASTM A53 Grade B is extra popular than different grades. These pipes could be naked pipes without any coating, or it could also be Hot-Dipped or Zinc-Coated and manufactured by Welding or by a Seamless manufacturing process. In Oil and Gas, A53 grade pipes are used within the structural and non-critical functions.

In the appliance of submarine oil and fuel pipeline engineering, ERW welded pipes are secure and economical.