Quality inspection of double-sided submerged arc welding spiral steel pipe

The double-sided submerged arc welded spiral steel pipe should be subjected to mechanical performance test, flattening test and flaring test before leaving the factory, and must meet the standard requirements. The quality inspection method of double-sided submerged arc welded spiral steel pipe is as follows:

1. Judging from the surface, that is, visual inspection. Visual inspection of welded joints is a simple and widely used inspection method. This is an important part of finished product inspection, mainly to find defects and dimensional deviations on the welding surface. It is usually inspected with the naked eye with the help of standard templates, gauges and magnifying glasses. If there are defects on the surface of the weld, there may be defects inside the weld.

2. Physical inspection: Physical inspection is a method that uses certain physical phenomena to measure or inspect. The inspection of internal defects of materials or workpieces usually adopts non-destructive testing methods. Non-destructive testing includes ultrasonic testing, radiographic testing, penetrating testing, magnetic testing, etc.

3. Strength test of pressure vessel: In addition to the tightness test, the pressure vessel must also be tested for strength. There are two types: hydraulic test and pneumatic test. They can test the welding tightness of containers and pipes that work under pressure. The air pressure test is more sensitive and faster than the water pressure test, and the tested product does not need to be drained, which is especially suitable for products with difficult drainage. But the risk of testing is greater than the risk of hydraulic testing. When conducting the test, the corresponding safety technical measures must be followed to prevent accidents during the test.

4. Tightness test: Welded containers used to store liquid or gas, through tightness test can find non-dense defects of the weld, such as penetration cracks, pores, slag inclusion, incomplete penetration and loose structure, air tightness test Methods include: water-carrying test, kerosene test, washing test, etc.

According to the quality inspection results of spiral steel pipes, spiral steel pipes are usually divided into three categories: qualified products, repair products and scrap products. Qualified products refer to the appearance and internal quality of spiral steel pipes that meet the relevant standards or technical requirements for delivery acceptance; products after repairs It means that the appearance and internal quality do not fully meet the standards and acceptance standards, but they are allowed to be repaired, and the standards and acceptance conditions can be met after repairs. Spiral steel pipe scrap refers to the appearance and internal quality of the spiral steel pipe that does not meet the standards, and it is not allowed to be repaired or does not meet the standards and acceptance conditions after repair.

Waste is divided into internal waste and external waste. Internal waste refers to discarded spiral steel pipes found in the foundry. External waste refers to the waste found after the delivery of the spiral steel pipe, which is usually exposed during machining, heat treatment or use, and the economic loss caused is far greater than the internal waste. In order to reduce external waste, the spiral steel pipes produced in batches should be sampled before leaving the factory for experimental heat treatment and rough machining. As far as possible, find potential spiral steel pipe defects in the spiral steel pipe factory so that necessary remedial measures can be taken as soon as possible.

The ASTM A500 specification covers cold-formed welded and seamless carbon steel tubing in round, square, rectangular, and “special” shapes for welded, riveted, or bolted construction applications, as well as for general structural purposes.

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