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How to Detect the Quality of Spiral Steel Pipe

Spiral pipe factory should be done before the mechanical performance test and flattening test, and flaring test, and to achieve the standard requirements. Spiral steel pipe quality inspection method is as follows:
1, From the face of it, that is visual inspection. Visual inspection of welded joints is a simple procedure but widely used test method is an important part of product testing, the main defects and deviations are found on the surface of the weld size. Usually by the naked eye, with the standard model, gauge and test tools such as a magnifying glass. If the weld surface defects, weld defects there may be internal.

2, Physical test methods: physical test method is to use some physical phenomena assay or test method. Or within the workpiece material defect inspection, and are generally used NDT methods. NDT ultrasonic flaw detection, radiation detection, penetration testing, magnetic testing and so on.

3, Pressure vessels strength test: pressure vessels, in addition to tightness test, but also the strength test. There are common test of two hydraulic test and air pressure. They can be tested in working under pressure vessels and piping welds compactness. Hydrostatic pressure test is more sensitive than the test speed and, at the same time after the test products do not waste water treatment, drainage problems for the product is particularly applicable. But the risk is greater than the test pressure test. When tested, it must comply with the appropriate safety measures to prevent accidents during the test.

4, Compact test: liquid or gas storage vessel welding, which is not dense weld defects, such as penetrating cracks, pores, slag, incomplete penetration loose tissue and the like, can be used to find the density test. Compactness test methods are: kerosene test, carrying water testing, water will test.

5, The hydrostatic test should be done each pipe hydrostatic test without leakage, pressure test press Calculate P = 2ST / D where S- hydrostatic test stress test Mpa, hydrostatic test stress test according to the corresponding steel standard specifies the minimum degree of yield (Q235 is 235Mpa) 60% of the selection. Regulators time: D <508 test pressure holding time less than 5 seconds; D≥508 test pressure holding time less than 10 seconds 4, non-destructive testing of steel welding seam, strip end weld and circumferential joints should X-ray or ultrasonic inspection. For ordinary combustible fluid transport spiral steel to weld should be 100% SX-ray or ultrasound test, used for water, sewage, air, heating steam and other general transmission fluid with spiral weld steel pipe should be X-rays or ultrasonic inspection checks (20%).

The spiral steel pipe quality test results, spiral pipe usually divided into three categories: Qualified, rework and scrap. Qualified means the quality and appearance of the intrinsic quality to meet the standards or technical delivery and acceptance conditions spiral steel pipe; rework refers to the quality and appearance of the intrinsic quality does not fully comply with the acceptance criteria and strip body, but allow the repair after repair can meet the standards and acceptance conditions spiral pipe; waste refers to substandard quality and appearance of the intrinsic quality of spiral steel still not up to standard and acceptance conditions do not allow repair or rework later.