To verify whether the bleed bolt on a pipe fitting is leaking after installation, a combination of methods can be used. This approach covers the entire process-from preliminary screening to precise quantitative testing-to ensure sealing performance meets standards.
Basic Preparations
Seal all pipeline inlets and outlets as well as any irrelevant instrument ports; install a calibrated pressure gauge (with an accuracy class of 0.5 or better) at a critical point in the system.
Pressurize the pipeline with compressed air (or nitrogen) to a level 1.5 times the system's operating pressure (typically 0.2–0.5 MPa).
Ensure the testing environment is relatively quiet and clear away any debris around the bolt to avoid obstructing the area being inspected.
Common Detection Methods
Foam Detection Method (Preliminary Screening)
Evenly apply soapy water or a specialized leak-detection solution to all potential leak points, such as the threaded connection of the bleed bolt and the mating surfaces of the sealing gasket.
Observe the area for 3–5 minutes; the appearance of bubbles that persist and grow in size indicates a leak.
This method is simple and low-cost, making it ideal for quick, on-site preliminary checks.
Pressure Hold Test Method (Quantitative Verification)
Close the air inlet valve and begin the pressure hold test; maintain the pressure for at least 10 minutes.
Record the pressure gauge readings before and after the holding period; a pressure drop exceeding 5% of the initial value indicates a significant leak.
