ASTM A312 TP316L Austenitic Stainless Steel Seamless Pipe for ASME BPV Code Stamp U

ASTM A312 TP316L Austenitic Stainless Steel Seamless Pipe for ASME BPV Code Stamp U

1. ​​Dimensional Tolerances for Tubing​​

​​ASME SA-999 Dimensional Tolerances​​

• Precision cold-drawn seamless tubing per ASME SA-999

• OD Tolerance: ±0.10 mm (for OD ≤ 25.4 mm)

• Wall Thickness Tolerance: ±10% (minimum ±0.15 mm)

• Straightness: ≤1.5 mm/m length

2. ​​Pitting Corrosion Resistance Certification​​

​​ASTM G48 Method A | NACE MR0175/ISO 15156 Compliance​​

• Critical Pitting Temperature (CPT): ≥48°C (tested per ASTM G48 Method A)

• Test Parameters:

  • 6% FeCl₃ solution at 48±1°C for 72 hours

  • Acceptance Criteria: ≤1.0 mdd weight loss

• Qualified for Sour Service (H₂S environments) per NACE MR0175 Section MR0175 Table A.20

3. ​​Non-Destructive Examination (NDE) Assurance Protocol​​

A. ​​Hydrostatic Pressure Test​​

• ​​Procedure​​: Per ASME Sec. VIII UG-99(m)

• ​​Test Pressure​​: 1.5 × Design Pressure (MAWP)

• ​​Duration​​: ≥30 minutes visual inspection (zero leakage acceptance)

• ​​Documentation​​: ASME Form U-1 signed by AI

B. ​​Eddy Current Testing (ET)​​

• ​​Standard​​: ASME Sec. V Article 8 (Mandatory Appendix II)

• ​​Coverage​​: 100% tube length

• ​​Equipment​​: Differential rotating probe system

• ​​Calibration​​: ASME Calibration Tube Set P3-E2

• ​​Defect Rejection​​: ≥5% wall loss indication

C. ​​Ultrasonic Testing (UT) Option​​

• ​​Supplement Requirement​​: SA-688 Annex S4 (Austenitic Stainless Steel Tubing)

• ​​Method​​: Automated straight-beam immersion UT

• ​​Criteria​​: No indications exceeding DAC curve (20% DAC reference)

• ​​Trigger Condition​​: If specified by purchaser order​