API PUBL 325-1994

$28.60

An Evaluation of a Methodology for the Detection of Leaks in Aboveground Storage Tanks

Published By	Publication Date	Number of Pages
API	1994	98

Guaranteed Safe Checkout

Category: API

If you have any questions, feel free to reach out to our online customer service team by clicking on the bottom right corner. We’re here to assist you 24/7.
Email:[email protected]

Description

The American Petroleum Institute has undertaken a significant technical effort to define and advance the state of the art of leak detection in aboveground storage tanks (ASTs). This report presents the results of Phase N of the API leak detection program. The three research efforts that preceded Phase IV were focused on the assessment of leak detection technology for ASTs and a detailed evaluation of passive acoustic and volumetric measurement methods. Field tests conducted on operational ASTs as part of the Phase III effort demonstrated that accurate leak detection could be accomplished through acoustic and volumetric techniques, and suggested specific changes in system design and test protocol to improve the performance of each technology. Based upon the Phase III results, general recommendations were made regarding further experimental work.

In addition, a methodology was developed which combines multiple AST testing technologies in order to assess the integrity of an AST. The proposed methodology may also include multiple tests with each technology. This methodology is designed to verify the presence of a leak in the case of a detection, and thereby minimize the occurrence of erroneous decisions based on test results which indicate the presence of a leak when none exist (false alarms). Effectively combining independent test methods should result in a very robust leak detection practice. Three leak detection techniques were selected for evaluation in the Phase IV program: passive-acoustics, volumetric methods (including both level-and-temperature and mass measurement systems), and soil-vapor monitoring. Though soil-vapor monitoring was not evaluated in the previous phases of API's research, it was identified as a technology of interest to the industry and was included in this phase. Individually, all three of these technologies are believed to have the potential for reliably detecting small leaks in the floor of an AST. When used together, the reliability of the test results increases.

Other AST leak detection technologies exist, and new technologies and new implementation techniques are being developed. Other technologies may perform equally well in a similar test methodology; however, API has limited the focus of this research to the three technologies mentioned above. The test methodology presented here is one example of a method to improve the reliability of a test decision through the used of multiple testing techniques.

The proposed leak detection methodology was applied to 14 ASTs during an eight-week period between 15 March and 3 May, 1993, at a facility provided by Santa Fe Pacific Pipeline Partners, Inc..

The objectives of the Phase IV study were:

• to assess the applicability of the general features of the three AST leak detection technologies (acoustic, volumetric, and soil-vapor monitoring technologies) over a wide range of tank types, petroleum fuels, and operational conditions

• to assess the applicability of a general leak testing methodology for ASTs which involves multiple tests at multiple product levels in the tanks

• to determine the integrity of 14 ASTs using two or more test methods

Additional information