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

If there are some defects in the seamless steel pipe, it will undoubtedly have a fatal affect on the standard of our products. So learn how to keep away from these defects? Then you want to grasp the reasons for these defects. Permanent Steel Manufacturing Co.,Ltd will work with you to debate the precise causes for the eight defects of seamless steel pipes:

1. Seamless steel pipe-folding

It’s a linear or spiral, steady or discontinuous state that exists on the outer or inside surface of seamless steel pipe. The primary motive for the folding is poor high quality of the pipe material, folding itself, or inclusions, severe scratches and cracks on the surface, edges and corners within the grinding place, and folding after drawing. So as to avoid folding, the standard of the pipe materials ought to be improved and attention should be paid to inspection and grinding.

2. Seamless steel pipe-crack

Refers to the small cracks on the interior 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. Based on the evaluation of Permanent Steel Manufacturing Co., Ltd, the trigger is: the hot-rolled tube clean has subcutaneous bubbles and subcutaneous inclusions, and there are cracks or deep pits on the steel pipe before drawing. During the hot rolling or chilly drawing processes Longitudinal scratches or scratches occurred in the course of the operation. Preventing the formation of cracks additionally lies in bettering the quality of the tube blank and strengthening the inspection and grinding of the tube materials. At the same time, pitting, scratches and scratches must be averted throughout the chilly drawing manufacturing course of.

3. Seamless steel pipe-scratches

The characteristic of the defect is that there are longitudinally linear scratches of varying lengths on the inner and outer surfaces of the seamless pipe. Most of them are groove-shaped, however they could also be raised stripes. The main purpose for the scratches (chopping) is: there are inner markings on the pipe material, which cannot be eliminated during drawing, the iron oxide film stays on the steel pipe and the mold sticks to the steel, and the energy and hardness of the mold are insufficient or uneven. Fragmentation and put on happen, the hammer head is defective, and the sharp edges and corners of the hammer head transition part damage the mold. So as to stop scratches and scratches, the quality of each preparation course of before drawing must be improved, and molds with high power and hardness and good smoothness ought to be used.

4. Seamless steel pipe-pit

That is one in every of the most common floor defects of seamless pipes. Local depressions with totally different areas are distributed on the surface of the steel pipe. Some of them are periodic and a few are irregular. The pits are caused by iron oxide scale or other hard dirt pressed into the floor of the steel pipe throughout the drawing or straightening process, or the peeling of the unique peeling on the floor of the steel pipe. Shandong Jute Pipe Industry identified that the measures to forestall pits are to fastidiously examine the pipe materials and take away defects resembling warping, keep the work site, tools and lubricants clear, and stop oxide scale and dirt from falling on the floor of the steel pipe.

When there are clean or sharp spiral marks on the outer surface of the seamless steel pipe, the straightening machine ought to be checked. Due to the incorrect place and angle of the straightening roller, the steel pipe rubbed the shoulders on the edge of the straightening roller during straightening. There are worn grooves on the straightening roller, and each ends of the steel pipe could seem on the outer floor of the steel pipe. Pits.

5. Seamless steel pipe-pitted floor

It’s characterized by small pits within the type of items and dots on the surface of the steel pipe. The main reason for the pitting surface 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 form a pitted surface; the steel pipe is kept in a humid atmosphere, and even pitted rust occurs after water enters. After removing the rust spots Form pitted surface.

6. Seamless steel pipe-spots

Since seamless steel pipes are involved with water (or water vapor) during processing or storage and should not handled in time (similar to drying), tool steel the traces left by water evaporation are called water spots, akin to long contact with water or corrosive water Rust spots are formed when the substance is Water spots usually don’t have any depth, and rust spots usually corrode the surface of the steel pipe, and there’ll still be pitted surfaces after removal.

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 metallic substrate, and the person items are lumpy, discontinuous, rooted or not rooted on the pipe wall, but can’t 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 hot rolling just isn’t removed on the tube billet to chilly drawing; the unique deep and angular transverse pits on the steel tube After drawing, it kinds a warped skin.

8. Seamless steel pipe-scar

The inside and outer surfaces of the steel pipe were not removed in time as a result of defects corresponding to folding and warping. In the next processing, skinny slices that couldn’t be separated from the metallic substrate have been formed. A few of them had been lumpy, discontinuous, and rooted or not rooted on the pipe wall, however they couldn’t peel off naturally. , Called scarring. Surface defects must be checked and eliminated in time to get rid of scars.

Tips: ASTM A53 Grade B is more widespread than other grades. These pipes can be bare pipes with none coating, or it could also be Hot-Dipped or Zinc-Coated and manufactured by Welding or by a Seamless manufacturing course of. In Oil and Gas, A53 grade pipes are used in the structural and non-critical applications.

In the application of submarine oil and gas pipeline engineering, ERW welded pipes are protected and economical.