Double-sided submerged arc welding spiral steel pipe quality inspection

Double-sided submerged arc welded spiral steel pipes should undergo mechanical performance tests, flattening tests and expansion tests before leaving the factory, and must meet standard requirements. The quality inspection methods of double-sided submerged arc welded spiral steel pipes are as follows:

1. Judgment 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. Inspection by physical methods: Physical inspection is a method of measurement or inspection using certain physical phenomena. The inspection of internal defects in materials or workpieces usually uses non-destructive testing methods. Non-destructive testing includes ultrasonic testing, radiographic testing, penetrant testing, magnetic testing, etc.

3. Strength test of pressure vessels: In addition to the sealing test, the pressure vessel must also be tested for strength. There are two types: hydraulic testing and pneumatic testing. They can test the welding tightness of containers and pipes working under pressure. The air pressure test is more sensitive and faster than the water pressure test, and the tested products do not need to be drained, which is especially suitable for products with difficult drainage. But the risks of testing are greater than those of hydraulic testing. When conducting testing, appropriate safety technical measures must be followed to prevent accidents from occurring during testing.
4. Tightness inspection: For welded containers used to store liquids or gases, non-density defects of the weld can be found through tightness testing, such as penetration cracks, pores, slag inclusions, incomplete penetration and loose structures, air tightness testing Methods include: water test, kerosene test, water 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 relevant standards or technical requirements for delivery acceptance; repaired products It means that the appearance and internal quality do not fully meet the standards and acceptance criteria, but they are allowed to be repaired, and the standards and acceptance conditions can be met after repairs. Scraping of spiral steel pipes means that the appearance and internal quality of spiral steel pipes do not meet the standards and are not allowed to be repaired or do not meet the standards and acceptance conditions after repairs.
Waste is divided into internal waste and external waste. Internal waste refers to discarded spiral steel pipes found at the foundry. External waste refers to the waste found after the spiral steel pipe is delivered, which is usually exposed during mechanical processing, heat treatment or use, causing economic losses far greater than internal waste. In order to reduce external waste, mass-produced spiral steel pipes should be sampled for experimental heat treatment and rough processing before leaving the factory. Whenever possible, potential spiral steel pipe defects are discovered in the spiral steel pipe factory so that necessary remedial measures can be taken as soon as possible.