The spiral steel tube shall perform mechanical performance test and flattening test and expansion test before delivery, and meet the standard requirements. The quality test method of straight seam steel tube is as follows:
1. Judging from the surface, it is the appearance test. The appearance of the welding joint inspection is a kind of procedure is simple and widely used test method, is an important content of the finished product inspection, mainly found on the surface of the weld defects and size deviation. It is generally observed by the naked eye with standard samples, gauges and magnifying glasses. If the weld surface defects, there is a possibility of defects in the weld.
Physical examination: the physical examination method is the method which USES some physical phenomena to measure or test. Inspection of the internal defects of materials or workpieces is generally a method of non-destructive inspection. There are ultrasonic flaw detection, ray flaw detection, penetrating flaw detection, magnetic flaw detection and so on.
3. Strength test of the pressure vessel: the pressure vessel shall be tested for strength in addition to the sealing test. There are two kinds of water pressure test and air pressure test. Both of them can test the weld density of the vessels and pipes that work under pressure. The pressure test is more sensitive and faster than the water pressure test, and the products after the test are not treated with drainage, especially for the products with difficult drainage. But the test is more dangerous than the hydraulic test. In carrying out the test, the corresponding safety technical measures must be followed to prevent accidents during the test.
4, density inspection: the storage of liquid or gas welding containers, the weld is not dense defects, such as the perfoliate crack, air hole, slag inclusion, incomplete fusion and loose organization, etc., can be found with the density test. The test methods of compactness are: kerosene test, water carrying test, water impact test, etc.
5, hydrostatic test each steel pipe should be tested for hydrostatic pressure and no leakage phenomenon, testing pressure press try to calculate P = 2 S in st/D type - Mpa hydrostatic pressure test of test stress, hydrostatic test of test stress according to the corresponding yield of steel belt standard degree is the minimum value selection (Q235 235 Mpa) is 60%. Voltage stabilizing time :D<508 test pressure should be maintained for no less than 5 seconds; The test pressure shall not be less than 10 seconds, and the welding seam of the steel tube shall be tested, and X-ray or ultrasonic inspection shall be carried out for the welding seam of the steel pipe and the butt seam of the steel belt. For combustible fluid conveying with ordinary steel spiral weld should be 100% X ray and ultrasonic inspection, for water, sewage, ordinary, such as air, steam heating and fluid conveying with spiral weld steel pipe should be X-ray or ultrasonic inspection sampling (20%).
According to the quality inspection result of spiral steel tube, spiral steel tube is usually divided into three types: qualified products, repair products and waste products. Qualified products refer to the spiral steel tubes that conform to the relevant standards or the technical conditions of delivery and acceptance. The rework refers to the appearance quality and internal quality not fully conforming to the standard and acceptance bar body, but it is allowed to be repaired, and the spiral steel pipe can meet the standard and acceptance conditions after repair. Waste refers to the appearance quality and internal quality unqualified, not allowed to repair or repair after the standard and acceptance conditions of the spiral steel pipe.
Waste is divided into internal and external waste. Internal waste refers to the spiral steel pipe found in the foundry or foundry. Waste refers to the waste products found after delivery, usually in the process of machining, heat treatment or use, and the economic losses caused by it are far greater than that of the waste. To reduce the waste, the batch production of spiral steel pipe before they go out the best sampling for experimental and rough machining, heat treatment, as far as possible within the spiral steel pipe found potential spiral steel tube defects, in order to take the necessary remedial refers to as early as possible.