Four key points of steel pipe quality control
Date:2025-07-10View:25Tags:Pipe fitting,Alloy steel pipe,Epoxy pipe
1. Material composition and performance certification: plug the "source loophole"
Chemical component compliance
Suppliers are required to provide a smelting analysis report (Mill Test Report, MTR) to verify whether the element content (such as C, Mn, S, P) meets the standard (such as ASTM A106/A53, API 5L).
Key indicator control:
Carbon equivalent (Ceq) ≤0.43% (affects weldability)
Sulfur and phosphorus content ≤0.025% (prevent hot brittleness)
Mechanical property verification
Tensile test: Ensure that the tensile strength (UTS), yield strength (YS), and elongation meet the standards (such as API 5L PSL2 requires YS ≥ 358 MPa).
Impact toughness: Charpy V-notch impact energy at -20℃ ≥27J (required for severe cold environments).
Operation tips: Sample 3% of the batch of goods and send them to a third-party laboratory for re-inspection (such as SGS, TÜV).
2. Geometric dimensions and tolerance control: reject "invisible defects"
Dimensional accuracy
Outer diameter (OD) and wall thickness (WT) deviations must meet the following requirements:
ASTM standard: OD ± 0.75%, WT ≤ ± 12.5%
Strict project requirements: WT ≤ ± 10% (such as high-pressure oil and gas pipelines).
Ovality ≤ 1.5% (to prevent installation stress concentration).
Nondestructive testing (NDT) application
Detection method Applicable defect type Accuracy requirements
Ultrasonic (UT) Internal cracks, delamination Detection of defects ≥ Φ 2mm
Eddy current (ET) Surface microcracks, holes Depth ≥ 0.1mm
Radio (RT) Weld porosity, lack of fusion ASTM E94 II qualified
On-site practice: 100% UT detection within 200mm of each steel pipe end (stress concentration high incidence area).
3. Anti-corrosion and coating quality: Extend service life
Surface treatment meets standards
Sandblasting to Sa2.5 level (ISO 8501), anchor pattern depth 40-80μm (enhanced coating adhesion).
Coating performance verification
3LPE anti-corrosion layer: test peel strength (≥70N/cm, ISO 21809) and cathodic peeling (≤8mm, 48h test).
Galvanized layer: average thickness ≥85μm (ASTM A123), copper sulfate test ≥4 times without iron exposure.
Case lesson: Due to insufficient zinc layer thickness, a water supply project was corroded and perforated within 3 years, and the maintenance cost exceeded the initial cost by 200%.
4. Document traceability and anti-counterfeiting: smashing the "counterfeiting chain"
Blockchain quality assurance documents
MTR reports, test certificates, etc. are uploaded to blockchain platforms (such as IBM TradeLens) to ensure that they cannot be tampered with.
Physical identification comparison
The information on the steel pipe nameplate must be consistent with the document, including:
Furnace batch number, standard number, specification
Manufacturer stamp
