I. Visual Inspection
Surface Quality: Visually inspect the surface for smoothness, cracks, folds, scabs, and other defects.
Cross-section: Check for uniform wall thickness and neat cross-section.
Standard Basis: GB/T 2102-2006 "Acceptance, Packaging, Marking and Quality Certificate of Steel Pipes".
II. Dimensional Measurement
Tools: Use micrometers, vernier calipers, etc., to measure the outer diameter, wall thickness, and length.
Accuracy Requirements: Allowable deviation for outer diameter δ=(D-Di)/Di×100%, allowable deviation for wall thickness ρ=(S-Si)/Si×100%.
Standard Basis: GB/T 7735-2004 "Magnetic Particle Testing of Steel Pipes".
III. Material Analysis
Chemical Composition: Detect the content of elements such as carbon, manganese, and silicon using chemical analysis methods or instrumental analysis methods (such as direct-reading spectrometer).
Hazardous Elements: Strictly control the content of harmful elements such as As, Sn, Sb, Bi, and Pb.
Standard Basis: GB/T 222-2006 "Permissible Deviations in Chemical Composition of Finished Steel".
IV. Performance Testing
Mechanical Properties: Conduct tensile tests (stress and deformation measurement), impact tests (toughness measurement), and hardness tests (hardness measurement).
Technical Properties: Flattening test, flaring test, bending test, etc.
Standard Basis: GB/T 228.1-2010 "Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method".
V. Non-Destructive Testing
Methods: Ultrasonic testing, radiographic testing, magnetic particle testing, etc.
Purpose: To detect internal cracks, inclusions, and other defects.
Standard Basis: GB/T 5777-1996 "Seamless Steel Tube - Ultrasonic Testing Method".
