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Traits and causes of defects in seamless metal pipes Article – ArticleTed

Seamless metal pipe refers to a metal pipe that’s made from a single piece of metallic and has no seams on the floor. In accordance with the manufacturing methodology, seamless tubes are divided into hot-rolled tubes, cold-rolled tubes, chilly drawn seamless tubing, extruded tubes, jacked tubes, and many others. In accordance with the cross-sectional form, seamless metal tubes are divided into two varieties: spherical and special-shaped, and special-shaped tubes have varied advanced shapes comparable to sq., oval, triangular, hexagonal, melon-shaped, star-shaped, and finned tubes. The utmost diameter is 650mm, and the minimal diameter is 0.3mm. Relying on the applying, there are thick-walled tubes and thin-walled tubes.

Seamless metal pipes are primarily used as petroleum geological drilling pipes (octg pipes), cracking pipes for petrochemical industries, boiler pipes, bearing pipes, and high-precision structural metal pipes for cars, tractors, and aviation. Subsequently, if there are some flaws within the seamless metal pipe, it’s going to undoubtedly have a deadly affect on the standard of our merchandise. So find out how to keep away from these defects?

1. Seamless metal pipe folding

It’s a kind that exists on the outer or internal floor of seamless metal pipes in a straight or spiral, steady or discontinuous state. The principle motive for folding is that the standard of the pipe materials will not be good, there are folds in itself, or there are inclusions, critical scratches and cracks on the floor, there are edges and corners on the grinding place, and folds seem after stretching after drawing. With a purpose to keep away from folding, the standard of pipe materials ought to be improved and a focus ought to be paid to inspection and grinding.

2. Cracks in seamless metal pipes

Refers back to the small cracks distributed in a straight line or helically on the internal and outer surfaces of seamless metal pipes, with a depth of 1 mm or extra, steady and discontinuous. The explanations are: the hot-rolled tube billet has subcutaneous air bubbles and subcutaneous inclusions, there are cracks or deep pits on the metal pipe earlier than drawing, and longitudinal scratches or scratches happen throughout scorching rolling or chilly drawing operations. . Stopping the formation of cracks additionally lies in enhancing the standard of the tube billet and strengthening the inspection and grinding of the tube materials. On the similar time, it’s essential to keep away from pitting, scratching and scratching of the pipe throughout the chilly drawing manufacturing course of.

3. Seamless metal pipe scratches

The attribute of the defect is that there are longitudinal linear scratches of various lengths on the internal and outer surfaces of the seamless pipe, principally within the type of grooves, however it might even be raised stripes. The principle motive for scratches (scratches) is: there are inner scratches on the pipe materials, which can’t be eradicated throughout drawing, and there are residual iron oxide scales on the metal pipe, and the mould sticks to metal. The energy and hardness of the mould aren’t sufficient or uneven, the mould is cracked and worn, the hammer head is dangerous, and the sharp edges and corners of the transition a part of the hammer head injury the mould, and many others. With a purpose to stop scratches and scratches, the standard of every preparation course of earlier than drawing ought to be improved, and molds with excessive energy and hardness and good end ought to be used.

4. Seamless metal pipe pits

This is among the most typical floor defects of seamless pipes. Native depressions with totally different areas are distributed on the floor of metal pipes, a few of that are periodic and a few are irregular. The pits are attributable to iron oxide scale or different laborious filth being pressed into the floor of the metal pipe throughout the drawing or straightening course of, or the peeling of the warped pores and skin that initially existed on the floor of the metal pipe. The measure to forestall pits is to fastidiously examine the pipe materials and take away defects comparable to warped pores and skin, hold the work website, instruments and lubricants clear, and forestall iron oxide scale and filth from falling on the floor of the metal pipe.

When there are easy or sharp-edged spiral marks on the outer floor of the seamless metal pipe, the straightener ought to be checked. As a result of the place of the straightening curler is wrong and the angle is wrong, the metal pipe rubs towards the shoulder of the straightening curler edge throughout straightening. There are worn grooves on the straightening curler, and pits might seem on the outer floor of the metal pipe if each ends of the metal pipe are bent an excessive amount of.

5. Seamless metal pipe pitted floor

It’s characterised by flakes and dot-like small pits on the floor of the metal pipe. The principle motive for pitting is pitting corrosion throughout pickling. After annealing, the oxide scale is simply too thick and straightened, after which pressed into the floor of the metal pipe to kind pitting. The storage setting of the metal pipe is humid, and even spot corrosion happens after getting into the water, and a pitted floor is shaped after the rust spots are eliminated.

6. Seamless metal spot

Because the seamless metal pipe is in touch with water (or water vapor) throughout processing or storage and isn’t handled in time (comparable to drying), the traces left after the water evaporates are referred to as water spots. Whether it is in touch with water for a very long time, or if the water comprises corrosive substances, rust spots will kind. Water spots usually haven’t any depth, whereas rust spots typically corrode to the floor of metal pipes, and there’ll nonetheless be pockmarks after cleansing.

7. Seamless metal pipe warping

It’s characterised in that the internal and outer surfaces of the seamless metal pipe have partially separated flakes from the metallic matrix, that are individually blocky and discontinuous, rooted or not rooted on the pipe wall, however can’t be naturally peeled off. The explanations are that the metal high quality is poor, there are subcutaneous air bubbles, that are uncovered after chilly drawing; the warped pores and skin produced throughout scorching rolling will not be eliminated on the tube clean and delivered to chilly drawing. The unique deep and angular transverse pits on the metal pipe are drawn to kind warped skins.

8. Scarring of seamless metal pipe

The internal and outer surfaces of the metal pipe aren’t eliminated in time as a consequence of defects comparable to folding and warping, and flakes that can’t be separated from the metallic matrix are shaped in subsequent processing. Particular person lumps, discontinuous, rooted or not rooted on the tube wall, however cannot peel off naturally, referred to as scarring. Floor defects should be fastidiously checked and eliminated in time to get rid of scarring.

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