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 should undoubtedly have a fatal affect on the quality of our products. So the way to avoid these defects? Then you definately need to understand the reasons for these defects. Permanent Steel Manufacturing Co.,Ltd will work with you to debate the particular 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 surface of seamless steel pipe. The principle purpose for the folding is poor quality of the pipe materials, folding itself, or inclusions, severe scratches and cracks on the surface, edges and corners in the grinding place, and folding after drawing. With a purpose to avoid folding, the standard of the pipe materials needs to be improved and a focus needs to be paid to inspection and grinding.
2. Seamless steel pipe-crack
Refers to the small cracks on the inside 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, steady and discontinuous. In line with 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 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 needs to be averted through the chilly drawing manufacturing 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-shaped, but they could even be raised stripes. The main cause for the scratches (chopping) is: there are inside markings on the pipe material, which can’t be eradicated throughout drawing, seamless steel tube the iron oxide movie 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 happen, the hammer head is defective, and the sharp edges and corners of the hammer head transition part damage the mold steel. In order to prevent scratches and scratches, the quality of every preparation process earlier than drawing ought to be improved, and molds with high energy and hardness and good smoothness ought to be used.
4. Seamless steel pipe-pit
That is one among the most typical floor defects of seamless pipes. Local depressions with completely different areas are distributed on the floor of the steel pipe. Some of them are periodic and some are irregular. The pits are attributable to iron oxide scale or other onerous dirt pressed into the surface of the steel pipe in the course of the drawing or straightening process, or the peeling of the original peeling on the surface of the steel pipe. Shandong Jute Pipe Industry pointed out that the measures to prevent pits are to fastidiously examine the pipe materials and take away defects similar to warping, keep the work site, tools and lubricants clear, and forestall oxide scale and dirt from falling on the floor of the steel pipe.
When there are easy or sharp spiral marks on the outer surface of the seamless steel pipe, the straightening machine ought to be checked. Due to the incorrect position and angle of the straightening roller, the steel pipe rubbed the shoulders on the edge of the straightening roller throughout straightening. There are worn grooves on the straightening roller, and each ends of the steel pipe could seem on the outer surface of the steel pipe. Pits.
5. Seamless steel pipe-pitted surface
It’s characterized by small pits within the form of pieces and dots on the floor of the steel pipe. The primary purpose 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 form a pitted floor; the steel pipe is saved in a humid surroundings, and even pitted rust happens after water enters. After eradicating the rust spots Form pitted floor.
6. Seamless steel pipe-spots
Since seamless steel pipes are in contact with water (or water vapor) throughout processing or storage and will not be handled in time (reminiscent of drying), the traces left by water evaporation are referred to as water spots, such as lengthy contact with water or corrosive water Rust spots are formed when the substance is Water spots usually have no depth, and rust spots often corrode the surface of the steel pipe, and there will nonetheless be pitted surfaces after removal.
7. Seamless steel pipe-warped skin
It’s characterized in that the inner and outer surfaces of the seamless steel pipe are partially separated from the steel substrate, and the person items are lumpy, discontinuous, rooted or not rooted on the pipe wall, but can’t peel off naturally. The explanations are poor steel high quality, the existence of subcutaneous bubbles, that are uncovered after cold drawing; the warping produced during hot rolling is not removed on the tube billet to chilly drawing; the original deep and angular transverse pits on the steel tube (from devpost.com) After drawing, it types a warped pores and skin.
8. Seamless steel pipe-scar
The inner and outer surfaces of the steel pipe weren’t removed in time as a consequence of defects corresponding to folding and warping. In the following processing, thin slices that could not be separated from the metal substrate had been formed. A few of them were lumpy, discontinuous, and rooted or not rooted on the pipe wall, but they could not peel off naturally. , Called scarring. Surface defects must be checked and removed in time to remove scars.
Tips: ASTM A53 Grade B is more well-liked than other grades. These pipes could be bare pipes without any coating, or it may 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-important purposes.
In the applying of submarine oil and gasoline pipeline engineering, ERW welded pipes are secure and economical.