Quality inspection of large diameter spiral steel pipe

According to the quality inspection results of large-diameter spiral steel pipes, large-diameter spiral steel pipes are usually divided into three categories: qualified products, repaired products and waste products. So how to detect it?

1. Inspection of physical methods: The physical inspection method is a method of measuring or testing by using some physical phenomena.

2. Strength test of pressure vessels: In addition to the tightness test, the strength test is also required for pressure vessels. There are two common types of hydraulic test and air pressure test. They both test the tightness of welds in vessels and pipes operating under pressure. The air pressure test is more sensitive and faster than the water pressure test. At the same time, the large-diameter spiral steel pipe after the test does not need to be drained, which is especially suitable for products with difficult drainage. However, the risk of the test is greater than that of the hydrostatic test. During the test, the corresponding safety technical measures must be followed to prevent accidents during the test.

3. Hydrostatic test: each large-diameter spiral steel pipe should be hydrostatically tested without leakage, and the test pressure should be calculated according to P=2ST/D. The test stress is selected according to 60% of the yield value specified in the corresponding steel strip standard.

4. Judging from the surface, that is, the appearance inspection, is a simple and widely used inspection method. It is an important part of the inspection of the finished product, mainly to find defects on the surface of the weld and dimensional deviations. Generally, inspection is carried out by visual inspection with the help of standard templates, gauges and magnifying glasses. If there is a defect on the surface of the weld, there is a possibility of a defect inside the weld.