Hebei Spiral Steel Pipe Factory: How to Conduct Quality Inspection of Spiral Steel Pipes
2022-05-07
Before leaving the factory, spiral steel pipes shall undergo mechanical property testing, flattening tests, and flaring tests, and must meet the requirements specified in the relevant standards prior to shipment. The quality inspection methods for spiral steel pipes are as follows:
1 From a surface‑level perspective, that is, during visual inspection, the visual examination of welded joints is a simple yet widely used method and an essential part of final‑product inspection. Its primary purpose is to identify surface defects and dimensional deviations in the weld. Typically, this inspection is performed with the naked eye, aided by standard templates, gauges, and magnifying glasses. If defects are present on the weld surface, it can be reasonably assumed that corresponding defects also exist within the weld.
2. Physical testing: Physical testing is a method that employs certain physical phenomena for measurement or inspection. Typically, nondestructive testing is used to detect internal defects in materials or workpieces. Nondestructive testing techniques include ultrasonic testing, radiographic testing, penetrant testing, magnetic particle testing, and others.
3. Pressure vessel strength testing: In addition to leak‑tightness tests, pressure vessels must also undergo strength tests. Hydrostatic and pneumatic tests are commonly used. These tests can verify the weld integrity of vessels and piping operating under pressure; pneumatic testing is more sensitive and faster than hydrostatic testing. Moreover, the test piece does not require draining, making it particularly suitable for products where drainage is difficult. However, this type of test is inherently more hazardous than hydrostatic testing. During the test, appropriate safety measures must be strictly observed to prevent accidents.
4. Leakage Test: For welded vessels used to store liquids or gases, leakage tests can detect non‑tightness defects in the welds, such as through‑cracks, porosity, slag inclusions, incomplete fusion, and coarse microstructure. Common leakage test methods include the kerosene test, the water‑pressure test, and the water‑flushing test.
5. Hydraulic pressure test: Each steel pipe shall undergo a hydraulic pressure test, with no leakage. The test pressure shall be calculated according to the following formula: P=2ST/D Formula, S —Test stress for the hydrostatic test Mpa . The test stress for the hydrostatic pressure test shall be based on the specified small yield strength stipulated in the relevant steel strip standard ( Q235 For 235 percent of megapascals) 60 Choose here. Voltage regulation time: D Less than 508 , the test pressure-holding time shall be no less than 5 seconds; D508 The test pressure shall be maintained for no less than 10 Seconds. Repairs to steel pipe welds, butt welds, and circumferential welds shall be performed… x Radiographic or ultrasonic examination. Steel pipes with longitudinal spiral welds used for conveying flammable and ordinary fluids shall be subjected to … percent. 100 s x Radiographic or ultrasonic testing, used for conveying water, sewage, air, and heating steam (percent 20 ) Spiral welds of steel pipes for ordinary fluids shall be subjected to x Radiographic or ultrasonic nondestructive testing sampling inspection.
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