Tests Required for High-Frequency Welded Steel Tubes
1. Chemical Composition Analysis
The chemical composition of high-frequency welded steel tubes has a significant impact on their properties, necessitating chemical composition analysis. This is typically conducted through chemical analysis or instrumental analysis methods, such as infrared C-S analyzers and direct-reading spectrometers, to analyze the content of elements like C, S, Si, Mn, P, Cr, Mo, Ni, etc., in the steel tubes.
2. Geometric Dimension and Shape Inspection
Wall Thickness Inspection: Tools like micrometers and thickness gauges are used to measure the wall thickness of the steel tubes, ensuring it falls within the specified tolerance range.
Outer Diameter and Ovality Inspection: The outer diameter and ovality of the steel tubes are measured using tools such as calipers, vernier calipers, and ring gauges to assess their geometric dimensional accuracy.
Length Inspection: Steel tapes and other tools are used to measure the length of the steel tubes, ensuring they meet the requirements for fixed or multiple lengths.
Bend Inspection: Tools like rulers, level bars, and feeler gauges are utilized to measure the bend per meter and total length bend of the steel tubes, guaranteeing their straightness.
Bevel Angle and Blunt Edge Inspection at Ends: Angle gauges and clamping plates are used to inspect the bevel angle and blunt edge dimensions at the ends of the steel tubes, ensuring they comply with welding requirements.
3. Physical Property Tests
Mechanical Property Tests: These include flattening tests, flaring tests, bending tests, and hardness tests, among others, to evaluate mechanical properties such as tensile strength, yield strength, and elongation of the steel tubes.
Hydraulic or Pneumatic Pressure Tests: Hydraulic or pneumatic pressure tests are conducted on the steel tubes to check their airtightness and weld strength. This is a crucial step in ensuring the steel tubes can withstand a certain internal pressure during use.
4. Non-Destructive Testing
Ultrasonic Testing: Ultrasonic testing is performed on the internal and external welds of the steel tubes, as well as the base material on both sides of the welds, to detect potential defects such as cracks and slag inclusions.
X-ray Inspection: X-ray industrial television inspection is conducted on the internal and external welds of the steel tubes, utilizing image processing systems to ensure the sensitivity of flaw detection and further confirm weld quality.
Eddy Current Testing: In some cases, eddy current testing may be used as an alternative to hydraulic pressure tests to detect defects on the surface and near-surface of the steel tubes.
5. Other Tests
Expanding Test: An expanding test is conducted on straight-seam submerged arc welded steel tubes to improve their dimensional accuracy and enhance the distribution of internal stresses.
Magnetic Particle Inspection at Tube Ends: Magnetic particle inspection is performed on the tube ends of the steel tubes to detect potential defects such as cracks.
