(Adopted 1/25/1994)

A. Applicability

This rule applies to equipment used in the production, gathering, storage, processing, and separation of crude oil and natural gas prior to custody transfer.

B. Exemptions

C. Definitions

See Rule 102 for definitions not restricted to interpretation of this rule.

"Alternate test method": A new method for testing that is not referenced in this rule or which involves major changes to a referenced test method.

"Average daily throughput": The quantity obtained by dividing the volume of crude oil which enters such tank in a calendar month by the number of days in that month.

"Custody transfer": The transfer of produced crude oil and/or condensate, after separation and/or treatment in production operations, from storage tanks or automatic transfer facilities to pipelines or any other form of transportation.

"Leak": A leak exists when one of the following conditions exists:

A leak is not a gaseous emission from pressure relief devices on tanks or delivery vessels when the process pressure exceeds the limit specified for the device.

"Liquid-tight": The absence of visible indications of recent seepage of tank contents on the outside of the tank.

"Out of service": A tank 1) in which there is no liquid present, 2) which is configured to allow easy verification of such emptiness by inspection, and 3) for which no concentrations of gaseous organic compounds greater than 1000 (one thousand) ppmv can be detected outside the tank using EPA Method 21.

"Petroleum material": Liquids resulting from petroleum production operations that contain more than five (5) milligrams per liter of reactive organic compound (ROC) material.

"Portable tank": A tank that can be moved from one location to another by attachment to a motor vehicle without having to be dismantled.

"Pressure vessel": Vessels rated, as indicated by an ASME pressure rating stamp, and operated to contain normal working pressures of at least 15 psig without vapor loss to the atmosphere.

"Produced gas": Organic compounds that are both 1) gaseous at standard temperature and pressure, and 2) associated with the production, gathering, separation or processing of crude oil or natural gas.

"Produced water": Water associated with the production, gathering, separation and processing of crude oil.

"Tank": A container, constructed primarily of nonearthen materials, used for the purpose of storing or holding petroleum material, or for the purpose of separating water and/or gas from petroleum material.

"Tank battery": Any tank, or any aggregation of tanks. An aggregation of tanks will be considered a tank battery only if the tanks are located so that no one tank is more than 150 feet from any other tank, edge to edge.

"Vapor pressure": The vapor pressure determined as described in Section G.2 of this rule.

"Vapor recovery system": Any reactive organic compound vapor control system which is designed to prevent the release or venting of reactive organic compound gases to the atmosphere under normal operating conditions.

"Wash tank": Any tank that is not a pressure vessel and is used for the purpose of the primary separation of crude oil from petroleum material.

"Wastewater separator": Any mechanical device used to separate crude oil and other material from produced water in petroleum production operations.

D. Requirements for Storage Tanks

E. Requirements for Produced Gas

F. Requirements - Recordkeeping

G. Requirements - Test Methods

H. Requirements - Inspection

The operator shall visually inspect any roof and internal floating cover and its closures and seals at least once every 5 years, and shall perform a complete inspection of any roof or cover whenever the tank is emptied for non-operational reasons or at least every 5 years, whichever is more frequent.

I. Compliance Schedule

Attachment A
American Petroleum Institute Nomograph
(API 2518)
True Vapor Pressures (P) of Crude Oils (2 psi to 15 psi RVP)

Attachment B
Technical Guidance Document to the Criteria and Guidelines Regulation for AB 2588
(Excerpt from pages 102. 103, and 114)
5. True Vapor Pressure (TVP)

True vapor pressure, the equilibrium partial pressure exerted by a volatile liquid, is perhaps the most difficult term in the breathing loss equation to calculate. A nomograph (included in Appendix E) relates TVP to both the Reid Vapor Pressure (RVP) and the storage temperature (Ts). RVP is the absolute vapor pressure of volatile crude oil and nonviscuous petroleum liquids. Numerically, the relationship between TVP, RVP, and temperature can be expressed by the following equation:


The value of the constant term CO depends on the given value of RVP.

Values of CO for different RVP numbers are tabulated in Appendix C. It should be noted, however, that an error was discovered in the API nomograph calculated values of TVP so that the RVP was not equal to TVP at 100°F as was expected given the general definition of RVP. Using linear regression techniques, correction factors (CF) were developed and should be added to the calculation values of TVP in order to obtain reasonable TVP numbers. The relationship between the three values is given as follows:

The correction factor was found to be dependent upon RVP according to the following equations:

RVP  CO __
0<RVP<2 -6622.5
2<RVP<3 -6439.2
RVP = 3  -6255.9
3<RVP<4 - 6212.1
RVP = 4 -6169.2
4<RVP<5 - 6177.9
RVP = 5  -6186.5
5<RVP<6 - 6220.4
RVP = 6 -6254.3
6<RVP<7 -6182.1
RVP = 7 -6109.8
7<RVP<8 - 6238.9
RVP = 8 -6367.9
8<RVP<9 - 6477.5
RVP = 9 -6587.9
9<RVP<10 - 6910.5
RVP = 10  -7234.0
10<RVP<15 - 8178.0
RVP > 15 -9123.2