UST Programs - LG 113

Issue Date: November 22, 1995
Revision Date: December 6, 2002

Tanknology - NDE

UTS-4T Ullage Test (Pressure Test)

NON-VOLUMETRIC TANK TIGHTNESS TEST METHOD (ULLAGE)

Certification	Leak rate of 0.1 gph with PD = 95.24% and PFA = 0%.
Leak Threshold	A tank system should not be declared tight when the make-up gas flow rate into ullage equals or exceeds 0.275 cubic feet/hour.
Applicability	Gasoline, diesel, aviation fuel, fuel oil #4. Other liquids may be tested after consultation with the manufacturer.
Tank Capacity	Maximum ullage volume is 7,500 gallons.
Waiting time	Minimum of 2 hours between delivery and testing.
Test Period	Minimum of 20 minutes, consisting of 2 consecutive 10-minute test periods. Test data are acquired and recorded manually. There must be no dispensing or delivery during test.
Test Pressure	Pressure must be increased in ullage such that total pressure at bottom of tank does not exceed 5.0 psi. Pressure must be maintained for a minimum of 5 minutes per 1,000 gallons of ullage. At conclusion of this stabilization period, ullage pressure must be reduced by 0.5 psi for remainder of test.
Temperature	Ullage must be monitored for rate of temperature change, which must not exceed manufacturer's tabulated values.
Groundwater	Depth to groundwater in tank excavation backfill must be determined. If groundwater is above product level, net pressure must exceed 1 psi in the ullage during test. If this requires more than 5 psi total pressure at tank bottom, the ullage test must not be used.
Comments	Not evaluated using manifolded tank systems. Evaluated using diesel. Tests only ullage portion of tank. Product-filled portion of tank must be tested using a volumetric underfill test method.

Tanknology - NDE	Evaluator: Midwest Research Institute
8900 Shoal Creek Blvd., Building 200	Tel: (816) 753-7600
Austin, TX 78757	Date of Evaluation: 12/04/92
Tel: (800) 800-4633

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