API RP 1621:1993(R2012) pdf download.Bulk Liquid Stock Control at Retail Outlets
1.1.1 The primary application of this recommended prac- tice is in connection with the underground storage of motor fuels and used oil at retail and commercial facilities. This recommended practice does not apply to inground (that is, where a part of the tank is aboveground) or aboveground bulk storage systems. Hereafter, the use of the term tank refers to an underground petroleum storage tank. Any mer- chandising operation in which a commodity is handled in bulk is susceptible to stock or inventory losses. This problem becomes even more critical at retail outlets selling motor fu- els since the principal bulk commodity handled is volatile. Thus, special care must be exercised to control product losses to (a) provide a safe environment for the operator, em- ployees, customers, and neighbors; (b) minimize air and wa- ter pollution; and (c) maximize profits.
1 .1 .2 The negative effect of product losses on profits needs no explanation. However, the operator should under- stand that he or she, as well as the owner of the underground storage and dispensing equipment, may be subject to finan- cial penalties imposed by government agencies if product leakage causes contamination. He or she may also be liable for personal injuries and property damage resulting from hazardous conditions caused by product leakage as a result of his or her negligence. Most states have regulations that contain penalties for noncompliance.
The U.S. Environmental Protection Agency (EPA) ac- cepts inventory control in conjunction with tank tightness testing as an approved method of release detection until De- cember 22, 1998, or 10 years after a new tank has been in- stalled or an existing tank has been upgraded, whichever comes later. The EPA requires that any suspected release be reported within 24 hours to the authority having jurisdiction. Authority having jurisdiction refers to one or more federal, state, or local government agencies or individuals responsi- ble for approving equipment, installations, and procedures associated with underground storage tank systems. When us- ing inventory control as a method of release detection, vari- ances exceeding 1 percent of product throughput plus 130 gallons for two consecutive months must be reported to the authority having jurisdiction. In addition, the tank tightness test must be capable of detecting a 0.1 gallon per hour leak rate with a 95 percent probability of detection and a 5 per- cent probability of false alarm. An alternate method of release detection accepted by the EPA is the use of an automatic tank gauging (ATG) system. The ATG must be capable of detecting a release equivalent to 0.2 gallons per hour with a 95 percent probability of de- tection and a 5 percent probability of false alarm during a monthly test. In addition to providing a tank testing feature, some ATG systems may be able to perform automatic inven- tory control. The scope of this recommended practice does not include additional discussion of ATG systems.
API RP 1621:1993(R2012) pdf download
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