Features and causes of eight defects of seamless steel pipe:folding, crack, scratches, pit, pitted floor, spots, warped pores and skin, scar.
If there are some defects within the seamless steel pipe, it'll undoubtedly have a fatal impact on the standard of our products. So the best way to avoid these defects? Then you need to understand the reasons for these defects. Permanent Steel Manufacturing Co.,Ltd will work with you to debate the precise reasons for the 8 defects of seamless steel pipes:
1. Seamless steel pipe-folding
It is a linear or spiral, steady or discontinuous state that exists on the outer or inner floor of seamless steel pipe. The principle cause for the folding is poor quality of the pipe material, folding itself, or inclusions, serious scratches and cracks on the floor, edges and corners within the grinding place, and folding after drawing. In an effort to keep away from folding, the quality of the pipe material should be improved and a focus should be paid to inspection and grinding.
2. Seamless steel pipe-crack
Refers back to the small cracks on the inside and outer surfaces of the seamless steel pipe which might be distributed in a straight line or a spiral, with a depth of 1 mm or more, continuous and discontinuous. According to the evaluation of Permanent Steel Manufacturing Co., Ltd, the cause is: the hot-rolled tube blank has subcutaneous bubbles and subcutaneous inclusions, and there are cracks or deep pits on the steel pipe earlier than drawing. During the recent rolling or chilly drawing processes Longitudinal scratches or scratches occurred through the operation. Preventing the formation of cracks also lies in bettering the quality of the tube clean and strengthening the inspection and grinding of the tube material. At the identical time, pitting, scratches and scratches needs to be avoided in the course of the chilly drawing manufacturing process.
3. Seamless steel pipe-scratches
The characteristic of the defect is that there are longitudinally linear scratches of various lengths on the internal and outer surfaces of the seamless pipe. Most of them are groove-shaped, however they may even be raised stripes. The principle reason for the scratches (slicing) is: there are inner markings on the pipe material, which can't be eliminated throughout drawing, the iron oxide movie remains on the steel pipe and the mold sticks to the steel, and the energy and hardness of the mold are inadequate or uneven. Fragmentation and put on occur, the hammer head is defective, and the sharp edges and corners of the hammer head transition half damage the mold. In order to stop scratches and scratches, the standard of every preparation process earlier than drawing ought to be improved, and molds with excessive power and hardness and good smoothness should be used.
4. Seamless steel pipe-pit
This is certainly one of the commonest floor 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 some are irregular. The pits are brought on by iron oxide scale or other exhausting dirt pressed into the floor of the steel pipe during the drawing or straightening process, or the peeling of the unique peeling on the floor of the steel pipe. Shandong Jute Pipe Industry pointed out that the measures to forestall pits are to fastidiously inspect the pipe material and take away defects comparable to 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 smooth or sharp spiral marks on the outer surface of the seamless steel pipe, the straightening machine needs to be checked. Due to the incorrect position and 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 each ends of the steel pipe may appear on the outer surface of the steel pipe. Pits.
5. Seamless steel pipe-pitted floor
It is characterized by small pits within the form of pieces 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 just too thick and straightened and pressed into the floor of the steel pipe to type a pitted surface; the steel pipe is saved in a humid surroundings, and even pitted rust happens after water enters. After removing the rust spots Form pitted floor.
6. Seamless steel pipe-spots
Since seamless steel pipes are in touch with water (or water vapor) during processing or storage and are not treated in time (akin to drying), 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 haven't any depth, and rust spots usually corrode the floor of the steel pipe, and there'll still be pitted surfaces after removing.
7. Seamless steel pipe-warped skin
It's characterized in that the interior and outer surfaces of the seamless steel pipe are partially separated from the metallic substrate, and the individual 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, that are exposed after cold drawing; the warping produced throughout hot rolling shouldn't 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 inside and outer surfaces of the steel pipe were not eliminated in time attributable to defects corresponding to folding and warping. In the subsequent processing, skinny slices that couldn't be separated from the metallic substrate had been formed. Some of them had been lumpy, discontinuous, and rooted or not rooted on the pipe wall, but they could not peel off naturally. , Called scarring. Surface defects should be checked and removed in time to remove scars.
Tips: ASTM A53 Grade B is extra in style than different grades. These pipes might 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 within the structural and non-important applications.
In the appliance of submarine oil and gas pipeline engineering, ERW welded pipes are protected and economical.