Hebei Spiral Steel Pipe Factory: How to Check the Quality of Spiral Steel Pipe
Before leaving the factory, the spiral steel pipe should be tested for mechanical properties, flattening and flaring, and should meet the requirements of the standard before leaving the factory. The quality inspection method of the spiral steel pipe is as follows:
1. From the surface, that is, in the visual inspection. Visual inspection of welded joints is a simple and widely used inspection method, and it is also an important part of finished product inspection, mainly to find defects and dimensional deviations on the surface of welds. Generally, it is checked with the naked eye, with the aid of standard templates, gauges and magnifying glasses. If the surface of the weld is defective, the interior of the weld is estimated to be defective as well.
2. Physical inspection: Physical inspection is a method of measuring or inspecting using some physical phenomena. Typically, non-destructive testing is used to inspect materials or workpieces for internal defects. Non-destructive testing includes ultrasonic, radiation, penetrant, magnetic testing, etc.
3. Pressure Vessel Strength Test: In addition to the tightness test, the pressure vessel should also be subjected to a strength test. Hydrostatic testing and pneumatic testing are common. It is possible to check the tightness of welding of vessels and pipes working under pressure; the air pressure test is more sensitive and faster than the water pressure test. At the same time, the tested product does not require drainage treatment, which is especially suitable for products with difficult drainage. However, this test is more dangerous than the hydrostatic test. During the test, it is necessary to comply with the corresponding safety technical measures to prevent accidents during the test.
4. Density test: For welded containers storing liquid or gas, non-compact defects of the weld, such as penetration cracks, pores, slag inclusions, incomplete welding and loose tissue, can be found through the density test. Intensity test methods include kerosene test, water test, water flushing test, etc.
5. Hydraulic test, each steel pipe should be hydraulically tested without leakage. The test pressure should be calculated according to the following formula: P=2ST/D formula, S—the test stress Mpa of the hydraulic test. The test stress of the hydrostatic test should be selected according to 60% of the minimum yield value (235 MPa for Q235) specified in the corresponding steel strip standard. Voltage stabilization time: D is less than 508, and the test pressure holding time is not less than 5 seconds; D508 test pressure should be maintained for not less than 10 seconds. Repairs to steel pipe welds, butt welds, and girth welds should be X-ray or ultrasonic inspection. 100% x-ray or ultrasonic flaw detection shall be carried out for steel-direction spiral welds used to transport flammable ordinary fluids, and steel pipe spiral welds used to transport ordinary fluids such as water, sewage, air and heating steam (20%) X-ray or ultrasonic inspection should be carried out.