DSAW steel pipe before leaving the factory should be tested for mechanical properties test and flattening test, flaring test, and to achieve the requirements of the standard. Straight seam steel pipe quality detection method is as follows:
1, judging from the surface, in the visual inspection. 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. Usually by the naked eye, with the aid of standard samples, gauges and magnifying glass test tool. If the weld surface defects, there exist inside weld defects.
2, physical methods of inspection, physical inspection method is to use some physical phenomena for measurement or test method. Internal defects of materials or the workpiece inspection, are generally adopt the method of nondestructive flaw detection. NDT with ultrasonic flaw detection, radiation detection, penetration inspection, magnetic testing etc.
3, the strength of the pressure vessel inspection: pressure vessel, except for leakage test and strength test. Two kinds of common water pressure test and pressure test. They can test to work under pressure vessel and mild steel pipe weld compactness. Pressure test than the hydrostatic test is more sensitive and fast, after test product without drainage treatment at the same time, the product is especially suitable for drainage difficulties. But the test of the dangers of larger than the hydrostatic test. During test, must observe the corresponding safety technical measures, in case of accidents occurred in the process of 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. Compactness testing method is: kerosene test, water test, impact test, etc.
5, hydrostatic test Each 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 yield degrees as stipulated in the corresponding standard steel belt 60% of the minimum value is 235 Mpa (Q235). Holding time: D < 508 test pressure holding time not less than 5 seconds; D p 508 test pressure holding time not less than 10 seconds 4 NDT repair welding of steel pipe, steel strip butt weld and circular seam welding seam should be x-rays or ultrasonic inspection. 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 results of the spiral welded steel pipe quality inspection usually spiral steel pipe can be divided into three categories: products, return product and waste. Product appearance quality and inner quality in accordance with relevant standards or acceptance of delivery technology condition of spiral steel pipe; Reprocessed product refers to the appearance quality and intrinsic quality is not completely conform to the standard and the acceptance of the body, but allow repair, repair after reaching standard and the acceptance criteria spiral steel pipe; Waste refers to the appearance quality and internal quality is unqualified, not allowed to repair or repair after still can not meet the standard and the acceptance criteria of spiral steel pipe.
Waste is divided into waste within and outside the two kinds of waste. Within the waste within the foundry or with the foundry waste found within spiral steel pipe; Outside waste refers to the waste of spiral steel pipe found after delivery, often in the process of machining, heat treatment or use didn't show it, the economic loss caused by far bigger than in 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.
If you would like to know more about this ,pls contact us:hunan great steel pipe co.,ltd
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