Methods and systems for the negative pressure testing of underground storage tanks containing highly vaporous hydrocarbon liquids
A method is described for detecting a leak in a normally high vapor evolving hydrocarbon liquid underground storage tank filled incompletely with said liquid and having a projecting fill pipe connected with the tank ullage which is filled with hydrocarbon vapor and air pockets; the steps of: (a) inserting a fill pipe plug mechanism incorporating passage mean communicating with said ullage, and communicating said passage means with a conduit system connected to a vacuum source and an outlet for withdrawing the atmosphere of said ullage and imposing a negative pressure thereon; (b) utilizing said vacuum source to draw off a portion of the ullage content; (c) bleeding off a significant portion of the ullage content withdrawn out said outlet while returning a portion to said conduit system and building the relative proportion of hydrocarbon vapor to air in said ullage; (d) discommunicating said ullage from said outlet while disabling said vacuum source, and allowing said air/hydrocarbon vapor mix to stabilize during a stabilization period with a consequent reduced rate of hydrocarbon vapor release into said ullage; (e) repeating at least steps (b) and (c) until the ullage content hydrocarbon vapor is sufficiently saturated that leakage tests can be performed at a predesignated negative pressure; and (f) over a predetermined time period taking successive negative pressure readings to indicate a possible rate of decay greater than a predetermined rate which would indicate a leak in the tank.
- Assignee:
- Horner Creative Products, Inc., Bey City, MI (United States)
- Patent Number(s):
- US 5216914; A
- Application Number:
- PPN: US 7-861263
- OSTI ID:
- 6478387
- Resource Relation:
- Patent File Date: 31 Mar 1992
- Country of Publication:
- United States
- Language:
- English
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03 NATURAL GAS
HYDROCARBONS
UNDERGROUND STORAGE
STORAGE FACILITIES
LEAK TESTING
AIR
INSTALLATION
MIXING
MIXTURES
PIPES
VACUUM SYSTEMS
VAPORS
DISPERSIONS
FLUIDS
GASES
ORGANIC COMPOUNDS
STORAGE
TESTING
022000* - Petroleum- Transport
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032000 - Natural Gas- Transport
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