Spiral steel pipe

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 before being released. The quality inspection methods for spiral steel pipes are as follows: 1. Visual inspection, i.e., external examination. Visual inspection of weld joints is a simple yet widely used method and an essential part of final‑product inspection, primarily aimed at identifying surface defects and dimensional deviations in the welds. Typically, this is performed with the naked eye, aided by standard templates, gauges, and magnifying glasses. If surface defects are found, it can be reasonably assumed that internal defects may also be present. Spiral Steel Pipes – Hebei Spiral Steel Pipes – Spiral Steel Pipe Manufacturer

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Spiral steel pipe

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Product Description

　　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, i.e., 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 similar defects may also exist within the weld.
　　Spiral Steel Pipe – Hebei Spiral Steel Pipe – Spiral Steel Pipe Manufacturer
　　2. Physical Testing: Physical testing is a method that employs certain physical phenomena to perform measurements or inspections. Typically, nondestructive testing is used to detect internal defects in materials or workpieces. Nondestructive testing encompasses techniques such as ultrasonic testing, radiographic testing, penetrant testing, and magnetic particle testing, among others.
　　3. Pressure Vessel Strength Testing: In addition to leak‑tightness testing, pressure vessels must also undergo strength testing. 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 testing is inherently more hazardous than hydrostatic testing. During the test, appropriate safety measures must be strictly observed to prevent accidents.
　　4. Leak‑tightness testing: For welded vessels used to store liquids or gases, leak‑tightness tests can detect non‑tightness defects in the welds, such as through‑cracks, porosity, slag inclusions, incomplete fusion, and coarse microstructure. Common leak‑tightness test methods include the kerosene test, the water‑pressure test, and the water‑flushing test.
　　5. Hydrostatic testing: Each steel pipe shall undergo a hydrostatic test with no leakage. The test pressure shall be calculated according to the following formula: P = 2ST/D, where S is the test stress in MPa. The test stress for the hydrostatic test shall be selected as 60% of the specified minimum yield strength stipulated in the relevant steel strip standard (235 MPa for Q235). Pressure-holding time: For pipes with D < 508 mm, the holding time shall be no less than 5 seconds; for D ≥ 508 mm, the test pressure shall be maintained for at least 10 seconds. Repairs to steel pipe welds, including butt joints and circumferential welds, shall be inspected by radiographic or ultrasonic testing. Steel pipes with helical welds used for conveying flammable ordinary fluids shall undergo 100% radiographic or ultrasonic inspection; steel pipes with helical welds used for conveying ordinary fluids such as water, sewage, air, and heating steam shall be subject to random radiographic or ultrasonic inspection.

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13 automated pipe‑making lines and 4 anti‑corrosion production lines, with an annual output of one million tons of steel pipes; all large‑diameter sizes are produced in‑house, ensuring stable lead times for bulk deliveries.

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Comprehensive nondestructive testing conducted by an independent laboratory, with dual certification under API and national standards; a long-term approved supplier for central state-owned enterprises, and fully qualified to bid on engineering projects.

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