The double-sided submerged arc welded spiral steel pipe produced by the ssaw steel pipe
factory shall be subjected to mechanical performance test, flattening test and flare test before leaving the factory, and meet the requirements of the standard. The quality inspection method is as follows:
1. Double-sided submerged arc spiral steel pipe is judged from the surface, that is, in appearance inspection. The appearance inspection of welded joints is a simple and widely used inspection method. It is an important part of the inspection of finished products, mainly to find defects and dimensional deviations on the surface of the weld. It is generally inspected by the naked eye and by means of tools such as standard templates, gauges and magnifiers. If there is a defect on the surface of the weld, there is a possibility of defects inside the weld.
2. Inspection of the physical method of double-sided submerged spiral spiral steel pipe: The physical inspection method is a method of measuring or inspecting using some physical phenomena. Inspection of the internal defects of materials or workpieces is generally carried out by means of non-destructive testing. Non-destructive testing includes ultrasonic flaw detection, radiographic inspection, penetrant inspection, and magnetic flaw detection.
3. Strength test of double-sided submerged arc spiral steel pipe pressure vessel: In addition to the sealing test, the pressure vessel shall be subjected to strength test. There are two types of hydraulic tests and air pressure tests. They are able to verify the weld density of containers and pipes that work under pressure. The air pressure test is more sensitive and rapid than the water pressure test, and the tested product does not need to be drained, which is especially suitable for products with difficult drainage. However, the risk of the test is greater than the hydrostatic test. When conducting tests, the corresponding safety technical measures must be observed to prevent accidents during the test.
4. Double-layer submerged arc spiral steel pipe compactness test: welded container for storing liquid or gas, its weld seam is not dense, such as penetrating cracks, pores, slag inclusions, incomplete penetration and loose structure, etc., can be used for compactness Experiment to find out. The methods of compactness test include: kerosene test, water carrying test, water flushing test, etc.
5. Double-sided submerged arc spiral steel pipe water purification test: Each steel pipe should be subjected to hydrostatic pressure test without leakage. The test pressure is calculated by pressing the test stress Mpa of the S-hydrostatic test in P=2ST/D type. The test stress of the hydrostatic test is selected according to the minimum specified yield of the corresponding steel strip standard (Q235 is 235Mpa). Regulating 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. Non-destructive testing of double-sided submerged arc spiral steel pipes: X-ray or ultrasonic inspection of repaired welds, steel-to-head welds and circumferential joints of steel pipes. For steel-welded spiral steel pipe welds for the transmission of combustible ordinary fluids, 100% SX-ray or ultrasonic inspection shall be carried out. X-ray or ultrasonic wave shall be applied to the spiral weld of steel pipes used for the transportation of ordinary fluids such as water, sewage, air and heating steam. Inspection and inspection (20%).
According to the quality inspection results of double-sided submerged arc spiral steel pipes, spiral steel pipes are generally divided into three categories: qualified products, repaired products and waste products. Qualified products refer to spiral steel pipes whose appearance quality and intrinsic quality meet the relevant standards or technical requirements for delivery acceptance; the repaired products refer to the appearance quality and internal quality which are not in full compliance with the standards and acceptance conditions, but are allowed to be repaired, and the standard and acceptance conditions can be met after rework. Spiral steel pipe; scrap refers to spiral steel pipe that is unqualified in appearance quality and internal quality, and does not meet the standard and acceptance conditions after repair or repair.