1. Chemical Composition Analysis
The chemical composition of high-frequency welded steel tubes has a significant impact on their performance, therefore, chemical composition analysis is necessary. 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 such as C, S, Si, Mn, P, Cr, Mo, Ni, etc., in the steel tubes.
2. Geometric Dimension and Shape Inspection
Wall Thickness Inspection: Tools such as micrometers and thickness gauges are used to measure the wall thickness of the steel tubes, ensuring they fall within the specified tolerance range.
Outer Diameter and Ovality Inspection: Tools like calipers, vernier calipers, and ring gauges are used to measure the outer diameter and ovality of the steel tubes, assessing 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 such as straightedges, levels, and feeler gauges are used to measure the bend per meter and total bend of the steel tubes, guaranteeing their straightness.
End Face Bevel Angle and Blunt Edge Inspection: Angle gauges and caliper plates are used to inspect the bevel angle and blunt edge dimensions of the steel tube ends, ensuring they meet welding requirements.
3. Physical Performance Tests
Mechanical Performance Tests: These include flattening tests, flare tests, bending tests, and hardness tests, which are used to evaluate mechanical performance indicators such as tensile strength, yield strength, and elongation of the steel tubes.
Hydraulic or Pneumatic Tests: Hydraulic or pneumatic tests are conducted on the steel tubes to check their airtightness and weld strength. This is an important step in ensuring that 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 and the base metal on both sides of the welds of the steel tubes 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, using image processing systems to ensure sensitivity in flaw detection and further confirm weld quality.
Eddy Current Testing: In some cases, eddy current testing may be used as an alternative to hydraulic testing to detect defects on and near the surface of the steel tubes.
5. Other Tests
Expanding Test: An expanding test is conducted on submerged arc welded straight seam steel tubes to improve their dimensional accuracy and improve the distribution of internal stresses within the tubes.
Magnetic Particle Inspection of Tube Ends: Magnetic particle inspection is performed on the tube ends of the steel tubes to detect potential defects such as cracks.
