Quality inspection methods for spiral steel pipes

The quality inspection methods for spiral steel pipes are as follows:

1 Judging from the surface, that is a 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 surface defects and dimensional deviations of welds. Generally, it is tested by naked eye observation with tools such as 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: The physical inspection method is a method of inspection or inspection using certain physical phenomena. Inspection of internal defects of materials or parts generally adopts non-destructive testing methods. X-ray flaw detection is one of the most commonly used methods for non-destructive testing of spiral steel pipes. The characteristics of this detection method are objective and direct, real-time imaging of X-ray machines, automatic judgment of defects by software, positioning of defects, and measurement of defect sizes.

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

4 Compactness test: Welded containers for storing liquids or gases, welds without dense defects such as penetrating cracks, pores, slag, impermeability loose organization, etc. can be used to find compaction tests. Densification test methods are kerosene test, water test, water test, etc.

5 Hydrostatic test Each steel pipe should be subjected to a hydrostatic test without leakage, and the test pressure is according to the test pressure P = 2ST / D, where S hydrostatic test pressure is Mpa, and the hydrostatic test pressure is 60% of the yield specified by the corresponding bar standard. Adjustment time: D <508 test pressure holding time is not less than 5 seconds; d ≥ 508 test pressure holding time is not less than 10 seconds.

6 Nondestructive testing of structural steel pipe welds, steelhead welds, and ring joints should be carried out by X-ray or ultrasonic testing. For steel spiral welds conveying flammable common fluids, 100% X-ray or ultrasonic testing should be carried out. Spiral welds of steel pipes conveying general fluids such as water, sewage, air, heating steam, etc. should be inspected by X-ray or ultrasonic testing. The advantage of X-ray testing is that the imaging is objective, the professional requirements are not high, and the data can be stored and traced.