How do spiral pipe manufacturers inspect pipe quality?

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2022-06-08

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The spiral tube manufacturer states that product inspection begins with surface‑level assessment, namely visual quality inspection. Visual examination of welded joints is a simple yet systematic and widely applied method, serving as a critical component of final‑product inspection, primarily aimed at identifying surface defects and dimensional deviations. Typically, manufacturers conduct such inspections by naked eye, supplemented by standard reference templates, gauges, and magnifying tools. If numerous surface defects are detected, there is a corresponding likelihood of internal defects within the weld.

　　 Spiral pipe manufacturer This refers to product inspection conducted through visual assessment, i.e., quality verification based on appearance. Visual inspection of welded joints is a simple yet systematic and widely applied method, constituting a critical component of final‑product inspection, primarily aimed at identifying surface defects and dimensional deviations in the weld. Typically, manufacturers perform such inspections by naked eye, supplemented by standard reference templates, gauges, and magnifying tools. If numerous surface defects are detected, there is a corresponding likelihood that internal defects may also be present.

　　1. Physical Testing Methods: Physical testing methods involve using certain physical phenomena to inspect and evaluate products from spiral pipe manufacturers. The detection of internal defects in materials or workpieces is typically carried out through nondestructive testing. Nondestructive testing techniques include ultrasonic testing, radiographic testing, penetrant testing, and magnetic particle testing.

　　2. Strength of Pressure Vessels: In addition to leak testing, pressure vessel manufacturers must also conduct strength tests. There are two types: hydrostatic testing and pneumatic testing. These methods are used to verify the tightness of welds in vessels and pipelines operating under pressure; pneumatic testing is more sensitive and faster than hydrostatic testing. Moreover, the test piece does not require drainage, which is particularly advantageous for products that are difficult to drain.

　　However, this test is more hazardous than a hydrostatic pressure test. During the test, appropriate safety measures must be observed to prevent accidents.

　　3. Tightness Testing: During storage, a container containing liquid or gas may develop non‑tight structural defects in its welds, such as through‑going cracks, porosity, slag inclusions, incomplete penetration, and looseness, as well as microstructural issues. Spiral pipe manufacturers can detect these defects using material tightness tests. Common tightness testing methods include kerosene penetration testing, water‑pressure testing, and hydrostatic testing.

　　4. Hydrostatic testing: Each steel pipe shall undergo a hydrostatic test with no leakage. The test pressure shall be 60% of the specified minimum yield strength (Q235: 235 MPa) as stipulated in the relevant steel grade standard.

　　Pressure‑holding time: For D < 508, the pressure‑holding time shall be no less than 5 seconds; for D ≥ 508, the pressure‑holding time shall be no less than 10 seconds. 4. With respect to nondestructive testing, repair welds, butt welds, and circumferential welds on steel strips shall be inspected by X‑ray or ultrasonic testing.

　　Spiral welds of steel pipes conveying flammable fluids shall be subjected to 100% radiographic or ultrasonic inspection, while spiral welds of steel pipes used for conveying water, sewage, air, heating steam, and similar media shall be inspected by radiography or ultrasonic testing (20%).

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