I. Pre-Test Preparations
Valve Status Check:
Confirm the ball valve is fully open or closed. Remove surface oil stains and impurities to avoid compromising sealing integrity.
Test Equipment Calibration:
Pressure gauges must have accuracy ≥ Class 1.6, with a range of 1.5–2 times the test pressure (referencing GB/T 12224).
Safety Protocols:
Establish isolation zones. Operators must wear protective gear (e.g., goggles, explosion-proof suits). Ambient temperature: -29°C to 50°C (per ASME B16.34).
II. Test Media and Pressure Parameters
Media Selection:
Prioritize dry nitrogen (purity ≥ 99.9%) or compressed air (dew point ≤ -40°C). Avoid moisture or corrosive gases.
Pressure Grading:
Low-Pressure Seal Test: 1.1× working pressure (e.g., 11 MPa for a 10 MPa valve).
High-Pressure Strength Test: 1.5× working pressure (e.g., 15 MPa for a 10 MPa valve). Hold time ≥ 10 minutes (API 598).
III. Test Procedure
Stepwise Pressurization:
Gradually increase pressure to 50% of test pressure, stabilize for 3 minutes to check leaks.
Raise to 100% test pressure, hold for 10 minutes, and record pressure drop.
Leak Detection:
Apply soap solution to seat-body joints; no bubbles indicate pass.
Allowable leakage rate: ≤ 0.1% (ISO 5208). Calculation:
Leakage = (Initial P – Final P) × Vessel Volume / Hold Time.
IV. Common Issues & Solutions
Sudden Pressure Drop:
Caused by seat damage or improper assembly. Disassemble to inspect sealing surface finish (Ra ≤ 0.8 μm).
Micro-Leakage Remediation:
Repeat test 2–3 times. If leaks persist, replace seals (material compliant with NACE MR0175 anti-sulfur requirements).
V. Standards & Acceptance
Results must comply with:
International: API 598 (Valve Testing), ISO 5208 (Leakage Class).
Domestic: GB/T 26480 (Valve Inspection and Testing), requiring pressure drop ≤ 5% with no visible leakage.