Quality Inspection of Spiral Pipe

　　Before the mechanical performance test, flattening test and expansion test, the screw pipe factory should carry out the test first and meet the standard requirements. Straight seam steel 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 etc.

　　5, Hydrostatic test: each pipe hydrostatic test should be done without leakage test pressure press Calculate P = 2ST / D where S- hydrostatic test stress test Mpa, hydrostatic test stress testing in accordance with corresponding steel standard specifies the minimum degree of yield (Q235 is 235Mpa) 60% of the selection.

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