Quality testing methods for spiral steel pipes

1. Judgment from the surface, that is visual inspection. The appearance 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. Testing is generally carried out through naked-eye observation and using 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: Physical inspection method is a method that uses certain physical phenomena to conduct inspection or inspection. Non-destructive testing methods are generally used to inspect internal defects in materials or parts. X-ray flaw detection is the most commonly used method for non-destructive testing of spiral steel pipes. The characteristics of this detection method are that it is objective and direct. The X-ray machine performs real-time imaging and the software automatically determines defects, locates defects, and measures 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 testing and pneumatic testing. They can test the weld density of vessels and pipes operating under pressure. Pneumatic testing is more sensitive and faster than hydraulic testing, and the tested products do not need to be drained, especially for products that are difficult to drain. However, the risks of testing are higher than hydraulic testing. During testing, appropriate safety and technical measures must be observed to prevent accidents from occurring during testing.

4. Compaction test: Welded containers that store liquids or gases. If the weld seam has no dense defects, such as penetrating cracks, pores, slag, impermeability, and loose tissue, it 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 should be subjected to a hydrostatic pressure test without leakage. The test pressure is based on the test pressure P = 2ST / D, where the hydrostatic test pressure S is Mpa, and the hydrostatic test pressure is determined by the corresponding 60% yield specified by bar standards. Adjustment time: D <508 test pressure is maintained for no less than 5 seconds; d ≥ 508 test pressure is maintained for no less than 10 seconds.

6. Non-destructive testing of structural steel pipe welds, steel head welds, and ring joints should be carried out by X-ray or ultrasonic testing. Steel spiral welds carrying flammable ordinary fluids shall be 100% X-ray or ultrasonic tested. Spiral welds of steel pipes transporting general fluids such as water, sewage, air, heating steam, etc. should be inspected by X-ray or ultrasonic waves. The advantage of X-ray inspection is that the imaging is objective, does not require high professionalism, and the data can be stored and traced.