UST: Installation Testing Requirements
and Cathodic Coatings Questions
Solved Correctly 2026/2027 Updated.
Preinstallation Single-walled tank Testing (Sec. 3.2)
(Before placing components in Excavation) - Answer Visual Inspection for damage or holes
3 to 5 psig air/soap test
3 psig for 12 ft diameter or greater tanks
According to manufacturer's instructions
Single-walled storage tank Testing
Before Placing the System in Service - Answer Tightness-test tank and piping
Preinstallation Double-walled tank testing (Sec 3.3, 3.5-7)
(Before placing components in Excavation) - Answer Inspection
Max of 5 psig air/soap test for one hour
-Seal inner tank and disconnect external air supply
-Pressurize interstice with air from the inner tank, measure interstice pressure with a third
gauge
-Soap and watch for bubbles or drop of pressure on the gauges
-First release pressure in interstice, then primary tank
Preinstallation Double-walled Tank with liquid-filled interstice Testing - Answer Carefully
inspect interior and exterior surfaces of tank for signs of leakage.
Check level of liquid in the interstice reservoir
Preinstallation Double-walled Tank with Vacuum on interstice Testing - Answer Check to
make sure the vacuum level in the interstice is within the limits designated by the manufacturer
Double-walled storage tank Testing (Sec 3.6-7)
Before Placing the System in Service - Answer Inspect tank interstice or check vacuum or
liquid level
Preinstallation Testing of Compartmented Tanks
Single-walled bulkheads - Answer Test compartments on different sides of the same
bulkhead at different times
, Preinstallation Testing of Compartmented Tanks
Double-walled bulkheads - Answer Compartments may be tested at the same time
Tank deflection Inspection (Sec 5.9)
After Assembly but before Backfilling - Answer Measure tank diameter before and after
installing anchor straps.
Acceptable deflection is established by the manufactorer
Tank shell deflection Testing
Before Placing the System in Service - Answer Compare before/after backfilling vertical
diameter. If measurements differ, consult manufacturer's instructions for allowable variation
Tank deflection is caused by - Answer Inadequate support or over-tightening of anchor straps
-Improper bedding
-Voids in the backfill under the tank-bottom quadrant
-Poor compaction of the backfill material at the tank sides
-Improper installation of anchor straps
Slope of excavation walls is determined by: - Answer Soil conditions
Depth of the excavation
Shoring requirements
Safety considerations
Excavation clearance 45" factor - Answer A straight line at a 45 degree angle from the
bottom of the tank tangentially to the side will meet a horizontal line that is 5 ft long extending
from the base of the nearby foundation
Filter fabrics are installed between:
This is to prevent the backfill from migrating and diminishing the support of the tank or paving -
Answer Backfill and adjacent unstable soils, bogs, swampy areas, or landfills.
Separate dissimilar backfill materials with filter fabric to prevent mixing
Foundation requirements for Steel underground tank - Answer -Bed of backfill material 1-ft
thick and extends 1-ft beyond the ends and sides of the tank
-At least 2-ft of backfill b/w adjacent tanks and b/w tanks and excavation walls.
and Cathodic Coatings Questions
Solved Correctly 2026/2027 Updated.
Preinstallation Single-walled tank Testing (Sec. 3.2)
(Before placing components in Excavation) - Answer Visual Inspection for damage or holes
3 to 5 psig air/soap test
3 psig for 12 ft diameter or greater tanks
According to manufacturer's instructions
Single-walled storage tank Testing
Before Placing the System in Service - Answer Tightness-test tank and piping
Preinstallation Double-walled tank testing (Sec 3.3, 3.5-7)
(Before placing components in Excavation) - Answer Inspection
Max of 5 psig air/soap test for one hour
-Seal inner tank and disconnect external air supply
-Pressurize interstice with air from the inner tank, measure interstice pressure with a third
gauge
-Soap and watch for bubbles or drop of pressure on the gauges
-First release pressure in interstice, then primary tank
Preinstallation Double-walled Tank with liquid-filled interstice Testing - Answer Carefully
inspect interior and exterior surfaces of tank for signs of leakage.
Check level of liquid in the interstice reservoir
Preinstallation Double-walled Tank with Vacuum on interstice Testing - Answer Check to
make sure the vacuum level in the interstice is within the limits designated by the manufacturer
Double-walled storage tank Testing (Sec 3.6-7)
Before Placing the System in Service - Answer Inspect tank interstice or check vacuum or
liquid level
Preinstallation Testing of Compartmented Tanks
Single-walled bulkheads - Answer Test compartments on different sides of the same
bulkhead at different times
, Preinstallation Testing of Compartmented Tanks
Double-walled bulkheads - Answer Compartments may be tested at the same time
Tank deflection Inspection (Sec 5.9)
After Assembly but before Backfilling - Answer Measure tank diameter before and after
installing anchor straps.
Acceptable deflection is established by the manufactorer
Tank shell deflection Testing
Before Placing the System in Service - Answer Compare before/after backfilling vertical
diameter. If measurements differ, consult manufacturer's instructions for allowable variation
Tank deflection is caused by - Answer Inadequate support or over-tightening of anchor straps
-Improper bedding
-Voids in the backfill under the tank-bottom quadrant
-Poor compaction of the backfill material at the tank sides
-Improper installation of anchor straps
Slope of excavation walls is determined by: - Answer Soil conditions
Depth of the excavation
Shoring requirements
Safety considerations
Excavation clearance 45" factor - Answer A straight line at a 45 degree angle from the
bottom of the tank tangentially to the side will meet a horizontal line that is 5 ft long extending
from the base of the nearby foundation
Filter fabrics are installed between:
This is to prevent the backfill from migrating and diminishing the support of the tank or paving -
Answer Backfill and adjacent unstable soils, bogs, swampy areas, or landfills.
Separate dissimilar backfill materials with filter fabric to prevent mixing
Foundation requirements for Steel underground tank - Answer -Bed of backfill material 1-ft
thick and extends 1-ft beyond the ends and sides of the tank
-At least 2-ft of backfill b/w adjacent tanks and b/w tanks and excavation walls.
