Spiral steel pipe
should be tested before the factory mechanical properties and flattening test and flaring test, and meet the requirements of the standard requirements.
The quality inspection method of spiral steel pipe is as follows:
1, judging from the surface, that is, in the visual inspection. The appearance inspection of welded joints is a simple procedure and a wide range of inspection methods. It is an important part of the inspection of finished products. It is mainly to find out the deviations of surface defects and dimensions of welds. It is generally observed by the naked eye and tested using tools such as standard models, gauges, and magnifiers. If the surface of the weld is flawed, the weld may be defective.
2. Physical testing methods: Physical testing methods are methods that use some physical phenomena for testing or testing. Inspection of internal defects in materials or parts generally uses nondestructive testing methods. Ultrasonic non-destructive testing, radiographic testing, penetration testing, magnetic testing, etc.
3, pressure vessel strength test: pressure vessel, in addition to the sealing test, but also to conduct strength tests. There are usually two types of hydraulic tests and barometric tests. They are able to test the welding density of containers and pipes working under pressure. Pneumatic tests are more sensitive and faster than hydrostatic tests, and products do not drain after testing, especially for products that are difficult to drain. But the risk of testing is better than hydraulic testing. During the test, corresponding safety and technical measures must be taken to prevent accidents during the test.
4. Compactness test: When storing liquid or gas welding vessels, there are no dense defects in the weld, such as penetrating cracks, pores, slag, non-penetration and loose tissue, etc., which can be used to find compact tests. Densification test methods include: kerosene test, water test, water test and so on.
5, hydraulic pressure test Each pipe hydraulic pressure test should be no leakage phenomenon, the test pressure in the test P = second / D, s-hydrostatic test pressure MPa, through the corresponding test stress with standard hydraulic test specified 60% minimum rate of return. 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. Non-destructive testing of steel pipe welds, steel head welds and ring joints shall be carried out using X-ray or ultrasonic testing. For spiral welds of flammable general fluid transport steel tubes, 100% X-ray or ultrasonic tests should be performed. Spiral welds of general fluid-conveying steel pipes such as water, sewage, air, and heating steam should be X-rayed or ultrasonically examined (20%).
According to the results of spiral steel pipe inspection, spiral steel pipes are generally divided into three categories: qualified products, rework, and waste products. Qualified products refer to the technical standards for the appearance quality and quality-related standards or delivery acceptance of spiral steel tubes; refurbished products refer to THs whose appearance quality and internal quality do not fully meet standards and acceptance. E bar, but the rework of the spiral steel pipe standards and acceptance conditions after the rework; waste is the quality of appearance and internal fault quality, can not still meet the spiral steel standards and acceptance conditions allow rework or repair my pipe.
Waste is divided into two types of waste and waste. Internal waste refers to scrap steel pipes found in the foundry or foundry. The scrap found after conveying spiral steel pipes is usually exposed to machining, heat treatment or use. The economic loss it causes is far greater than the internal loss. In order to reduce external waste, the best sampling and testing heat treatment and pre-roughing spiral steel pipe production in the factory, try to find potential spiral steel pipe defects in the spiral steel pipe plant in order to take the necessary early repair dial instructions.