Analysis Of Spiral Welded Pipe And Its Impact Toughness

The trend of pipeline development is large diameter and high strength. As the diameter of the steel pipe increases and the steel grade used increases, the tendency of the ductile fracture to expand and expand is greater. According to tests conducted by relevant research institutions in the United States, although the spiral welded pipe and the straight welded pipe are of the same grade, the spiral submerged arc pipe has high impact toughness.

Due to the change of the transmission line, the steel pipe is subjected to random alternating load during the actual operation. Understanding the low cycle fatigue strength of steel pipes is of great significance for judging the service life of pipelines.

According to the measurement results, the fatigue strength of the spiral welded pipe is the same as that of the seamless pipe and the erw steel pipe. The test data is distributed in the same zone as the seamless steel pipe and the resistance pipe, and is higher than the general buried arc straight seam welded pipe.

1. Fake and inferior spiral welded steel pipes are prone to folding. Folding is a variety of fold lines formed on the surface of steel pipes. Such defects often run through the longitudinal direction of the entire product. The reason for the folding is that the inferior manufacturer pursues high efficiency, the amount of pressing is too large, and the ear is generated, and the next rolling causes folding, and the folded product is cracked after bending, and the strength of the steel is greatly reduced.
2. The surface of the counterfeit steel pipe often has a pockmark phenomenon, and the pockmark surface is a defect that the irregularity of the steel surface is irregular due to the serious wear of the groove. Due to the pursuit of profit by shoddy steel pipe manufacturers, the most frequent rolling mill rolling is exceeded.
3. The surface of the fake steel pipe is prone to scarring. There are two reasons for this: (1) The material of the fake steel pipe is uneven and has many impurities. (2) The guide equipment of the fake inferior material manufacturer is simple and easy to stick steel. These impurities are easy to cause crusting after biting the roller.
4. The surface of the fake inferior material is prone to cracks because the billet is an adobe, and the adobe has many pores. The adobe is cracked by the action of thermal stress during the cooling process, and cracks occur after rolling.
5. Fake and inferior steel pipes are easy to scratch, because the equipment of the fake and inferior steel pipe manufacturers is simple, easy to produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of the steel.
6. The fake steel tube has no metallic luster and is light red or similar to pig iron. There are two reasons for this:(1) Its billet is an adobe.(2) The temperature of the fake inferior material rolling is not standard, and their steel temperature is visually measured, so that it cannot be rolled according to the specified austenite region, and the performance of the steel is naturally unable to reach the standard.

A worker from a steel pipe company, which is located in China.