Quality inspection method of spiral steel pipe

1 Judging from the surface, that is, in visual inspection. The visual inspection of welded joints is a simple procedure with a wide variety of inspection methods. It is an important part of finished product inspection, mainly to find welding surface defects and dimensional deviations. Generally, the test is carried out by visual observation, using standard models, gauges, and magnifying glasses. If there are defects on the surface of the weld, there may be defects in the weld.

2 Physical inspection method: Physical inspection method is a method of inspection or inspection using certain physical phenomena. Generally, non-destructive testing methods are used to inspect internal defects of materials or parts. X-ray inspection is the most commonly used method for non-destructive testing of spiral steel pipes. The characteristics of this inspection method are objective and direct. X-ray machine real-time imaging, the software automatically judges defects, locates defects, and measures defect sizes.

3 Strength test of pressure vessel: In addition to the sealing test, the pressure vessel is also subjected to a strength test. There are usually two types of hydraulic tests and pneumatic tests. They can test the welding density of vessels and pipes that work under pressure. The pneumatic test is more sensitive and faster than the hydraulic test, and the product after the test does not need to be drained, especially for products that are difficult to drain. But the risk of testing is higher than that of hydraulic testing. During the test, the corresponding safety and technical measures must be observed to prevent accidents during the test.

4 Compactness test: Welded containers that store liquid or gas, the weld has no dense defects, such as penetrating cracks, pores, slag, impermeability, and loose organization, etc., which can be used to find the compaction test. Densification test methods include kerosene test, water test, water test, etc.

5 Hydrostatic pressure test Each steel pipe shall be subjected to a hydrostatic pressure test without leakage. The test pressure shall be P = 2ST/D, in which the hydrostatic pressure test pressure of S is Mpa, and the hydrostatic pressure test pressure shall be determined by the corresponding bar. 60% of the output specified by the shape standard. Adjustment time: D <508 test pressure holding time is no less than 5 seconds; d ≥ 508 test pressure holding time is no less than 10 seconds.

6 Non-destructive testing of structural steel pipe welds, steelhead welds, and annular joints shall be X-ray or ultrasonic testing. For steel spiral welds conveyed by flammable ordinary fluids, 100% X-ray or ultrasonic testing should be carried out. The spiral welds of steel pipes that transport water, sewage, air, heating steam, and other general fluids should be inspected by X-ray or ultrasonic. The advantage of X-ray inspection lies in the objective imaging, low professional requirements, and the data can be stored and traced.