6
3.2.8. When the test is complete, carefully release the air
pressure from the tank by opening the air-supply valve.
3.2.9. When airflow stops, remove the test manifold.
3.2.10. Replace the protective covers in the service fittings.
3.3. TESTING A DOUBLE-WALL TANK WITH A DRY
INTERSTITIAL SPACE
3.3.1. GENERAL
3.3.1.1. The tank will arrive with a quick-disconnect assembly.
(See FIGURE 3-4.)
3.3.1.2. If the tank is not configured
as shown in FIGURE 3-4
prior to preinstallation testing, call the UST coordinator at the
Xerxes plant nearest you.
3.3.2. PRIMARY TANK (INTERNAL)
3.3.2.1. Remove all temporary service-fitting plugs.
3.3.2.2. Redope fittings and install plugs in all openings, except
one service fitting (needed for the test manifold).
Follow
instructions in Point 3.1.5.
3.3.2.3. Install the test manifold in the open service fitting. Connect
the pressure source to the test manifold.
(See FIGURE 3-4.)
FIGURE 3-4
3.3.2.4. In order to test the primary tank alone, the quick-
disconnect assembly must not be connected to the service
fitting – keep the nylon tie in place.
3.3.2.5. Pressurize the primary tank to 5 psig [3 psig for a 12-
foot-diameter tank]. Allow the pressure to stabilize by adding or
removing air as necessary.
3.3.2.6. Close the air-supply valve on the test manifold.
Disconnect the air-supply line.
3.3.2.7. Soap all service fittings and manways. Watch for active
air bubbles, which indicate a leak.
3.3.2.8. Monitor the pressure for one hour.
Monitor Fitting
Quic
k
-Disconnect
Assembly
Nylon
Tie
3.3.3. SECONDARY TANK (EXTERNAL)
3.3.3.1. Maintain the pressure in the primary tank.
Do not connect air supply directly to the interstitial-space
monitor fitting. Pressurizing the secondary tank (interstitial
space) by itself may damage the primary tank or cause
tank failure.
3.3.3.2. Free the hose from the service fitting by cutting the
nylon tie.
3.3.3.3. Insert the hose into the quick-disconnect fitting. This will
allow air to transfer from the primary tank to the secondary tank.
3.3.3.4. Reconnect the air-supply line. Allow the pressure to
stabilize at 5 psig [3 psig for a 12-foot-diameter tank] by adding
or removing air as necessary.
3.3.3.5. Close the air-supply valve on the test manifold.
Disconnect the air-supply line.
3.3.3.6. Soap the entire exterior of the tank, checking for leaks.
(Follow instructions in Points 3.1.6. through 3.1.8.,
including
Warnings following 3.1.8.)Watch for active air bubbles, which
indicate a leak. Pay special attention to fittings and manways.
3.3.3.7. Monitor the pressure for one hour.
3.3.3.8. When the test is complete, carefully release the air
pressure from the tank by opening the air-supply valve.
3.3.3.9. When the airflow stops, remove the test manifold.
3.3.3.10. Replace the protective covers in the service fittings.
3.4. TESTING A DOUBLE-WALL TANK WITH A WET
INTERSTITIAL SPACE
Never pressurize a wet interstitial space. Doing so may
damage the primary tank or cause tank failure.
3.4.1. PRIMARY TANK (INTERNAL)
3.4.1.1. Keep the tank vertical (the reservoir on top) at all times
or the monitoring fluid may drain from the reservoir.
3.4.1.2. Remove all temporary service-fitting plugs and the
reservoir-fitting plug.
3.4.1.3. Check the monitoring-fluid level in the reservoir. It
should be about 1/4 full.
3.4.1.4. Visually check the interior of the tank for monitoring
fluid.
There should not be any.
3.4.1.5. Redope fittings and install plugs in all openings, except
one service fitting (needed for the test manifold) and the reservoir
fitting.
Follow instructions in Point 3.1.5.
Do not open the
monitor fitting (if present) or monitoring fluid could be lost.
