Key words: How to test the quality of spiral steel tube
The spiral pipe factory should carry out mechanical performance test and flattening test, and carry out expansion test, and meet the standard requirements. The quality inspection methods of spiral steel pipe are as follows:
1. On the surface, it is visual inspection. Visual inspection of welded joints is a simple process, but widely used testing methods are an important part of product testing. The main defects and deviations are found on the welded surface. Usually with the naked eye, with standard models, instruments and test tools such as magnifiers. If there is a defect on the surface of the weld, there may be an internal defect in the weld.


2. Physical testing methods: Physical testing methods use some physical phenomena or testing methods. Or in the inspection of workpiece material defects, NDT method is generally used. NDT ultrasonic flaw detection, radiation detection, penetration test, magnetic test, etc.


3. Strength test of pressure vessel: In addition to sealing test, strength test should be carried out for pressure vessel. There are two kinds of hydraulic and pneumatic tests. They can be tested under tight welding conditions for pressure vessels and pipes. The hydrostatic pressure test is more sensitive than the test speed. At the same time, when the test product is not treated with wastewater, the drainage problem of the product is particularly applicable. But the risk is greater than the test stress test. During testing, proper safety measures must be observed to prevent accidents during testing.


4. Compact test: The welding of liquid or gas storage containers, which is not compact welding defects, such as penetrating cracks, pore, slag, incompletely permeable and loose structure, can be used to find density test. Compact test methods include kerosene test, carrying water test and water test.


5. Hydraulic test should be conducted without leakage. Pressure test pressure calculation P = 2ST/D includes S-hydraulic test stress test Mpa and hydraulic test stress test 60% of minimum yield degree (Q235 is 235 Mpa) according to corresponding steel standards. Regulator time: D < 508 test pressure holding time is less than 5 seconds; D < 508 test pressure holding time is less than 10 seconds 4. Non-destructive testing of steel bar weld, steel strip end weld and circumferential joint should be carried out by X-ray or ultrasonic inspection. 100% S X-ray or ultrasonic inspection should be used for welding of screw steel conveying common combustible liquid. It is used for general transmission fluids such as water, sewage, air and heating steam. X-ray or ultrasonic inspection should be carried out for spiral welded steel pipe (20%).


Spiral pipe quality testing results, spiral pipe is usually divided into three categories: qualified, rework and waste. Qualification refers to the internal quality of quality and appearance in order to meet the standards or technical delivery and acceptance conditions of spiral steel pipe; rework refers to the internal quality of quality and appearance that does not fully meet the acceptance criteria and belt body, but allows the repair after repair to meet the standards and acceptance conditions of spiral pipe; waste refers to the unqualified quality and appearance of spiral pipe. The internal quality of Rotary Steel still does not meet the standards, and the acceptance conditions do not allow future repair or rework.