How should the interstitial space be secured during testing to prevent interference?

How should the interstitial space be secured during testing to prevent interference?

• A. Leave it open to atmosphere
• B. Vent to atmosphere periodically
• C. Isolate interstitial space and ensure valves/pipes are tight to avoid flow or venting
• D. Open all valves to the tank interior

Answer: (C)

During a tank tightness test, any space that could interact with the outside world or other parts of the system must be sealed and kept under control. The interstitial space between tank walls should be isolated so that no air or vapor can vent to atmosphere and no external flow paths can alter the pressure. Keeping valves and pipes tight prevents unintended leaks or venting routes, ensuring the test pressure stays stable and any changes directly reflect the tank’s integrity rather than external interference. Leaving the interstitial space open to atmosphere, venting periodically, or connecting it to the tank interior would introduce unwanted air movement or pressure changes, leading to inaccurate results.

During a tank tightness test, any space that could interact with the outside world or other parts of the system must be sealed and kept under control. The interstitial space between tank walls should be isolated so that no air or vapor can vent to atmosphere and no external flow paths can alter the pressure. Keeping valves and pipes tight prevents unintended leaks or venting routes, ensuring the test pressure stays stable and any changes directly reflect the tank’s integrity rather than external interference. Leaving the interstitial space open to atmosphere, venting periodically, or connecting it to the tank interior would introduce unwanted air movement or pressure changes, leading to inaccurate results.