What is the common purpose for testing the interstice in a double-wall tank?

What is the common purpose for testing the interstice in a double-wall tank?

• A. To verify vent line integrity.
• B. To ensure no product bypasses the primary containment due to a leak in the interstitial space.
• C. To measure tank volume.
• D. To check color of interstitial fluid.

Answer: (B)

Testing the interstice checks the integrity of the space between the inner tank and the outer wall in a double-wall tank. The main goal is to ensure there is no leak path that would allow product to bypass the primary containment because of a leak in that interstitial space. By keeping the interstitial space leak-tight, any release from the inner tank would be contained or detected before it can reach the environment, providing a reliable secondary containment. This is why the test focuses on the interstice—to verify that the barrier between walls remains intact and capable of preventing uncontrolled releases.

Testing the interstice checks the integrity of the space between the inner tank and the outer wall in a double-wall tank. The main goal is to ensure there is no leak path that would allow product to bypass the primary containment because of a leak in that interstitial space. By keeping the interstitial space leak-tight, any release from the inner tank would be contained or detected before it can reach the environment, providing a reliable secondary containment. This is why the test focuses on the interstice—to verify that the barrier between walls remains intact and capable of preventing uncontrolled releases.