Detection Methods
1. Internal Leakage Identification
Infrared Thermometry:
Measure the temperature of the valve stem or downstream pipe (150 mm from the valve) 4–6 hours after closure. A temperature >70°C indicates leakage.
Note: Exclude interference from nearby high-temperature sources (e.g., steam pipelines).
Ultrasonic Testing:
Use sensors at designated points (A, B, C) to detect flow turbulence sounds through spectrum analysis.
Pressure Drop Test:
Monitor downstream pressure after closing the valve. Sustained pressure loss confirms internal leakage.
2. External Leakage Identification
Visual/Soap Bubble Test:
Observe visible leaks at joints or apply soapy water to suspected areas; bubbles indicate leakage points.
Ultrasonic Detection:
Capture high-frequency signals from escaping medium using portable devices.
Valve Integrity Check:
Pressurize the valve and use tracer gases (e.g., nitrogen) or bubble tests to identify defects like cracks.
Operational Considerations
For internal leakage:
Exclude environmental interference (e.g., steam disturbances).
Confirm findings with maintenance personnel to avoid false positives.
For external leakage:
Prioritize dynamic leaks during valve operation and long-term corrosion risks.
Follow standardized ultrasonic testing protocols to minimize noise interference.
Key Terminology
Internal Leakage: Incomplete sealing between internal components (e.g., valve core and seat) when closed.
External Leakage: Medium escaping from external seals (e.g., flange connections, valve stems).