this section is intended to describe the methods and procedures
available for determining the fill condition of pipeline systems, the
procedures described do not necessarily determine the precise volume of
liquids in the designated pipeline systems.
section is not meant to recommend equipment or to describe equipment in
detail. The guideline is only intended to describe the
expected end result of using properly installed and functioning
equipment. While this section includes descriptions of common line fill
verification methods, it does not recommend anyone method as
preferred. The responsibility for documenting the
effectiveness of any of the methods described belongs to those
responsible for the terminal or installation where it is applied.
custody of petroleum liquids is transferred to or from marine vessels,
accuracy in the measurement of quantities transferred is affected by
the contents and integrity of the shore and vessel pipelines and by
shore and vessel tank measurements. Pipelines that contain
air or vapour, when assumed to be filled with liquid, require
procedures that either eliminate or determine the volume of air or
vapour contained in the pipeline. This can be accomplished by
one of the following means:
Displacing the air or vapour with liquid.
Displacing the entire line contents
Quantifying the volume of any air or vapour contained in the line with
following methods, listed alphabetically, are recommended for line fill
determination. Local limitations, product characteristics,
and specific designs may restrict the best selection and use of a
procedure and may affect the accuracy of the procedure selected.
bleed-valve method (or sight-glass method).
press method (or line pack method)
high-point bleed-valve method (or sight-glass method), the internal
circulation method, and the line displacement method are all intended
to fill the designated pipeline system with liquid. The
method is intended to entirely displace the contents of the designated
pipeline system. The line press method (or line pack method)
intended to define the fill condition of the designated pipeline
line displacement method requires the presence of the vessel.
All other methods provide an opportunity for any correction required
without affecting the vessel's transferred volume.
procedures described and recommended here shall be performed in
accordance with the following:
safety requirements specified in the following:
International Safety Guide for Oil Tankers and Terminals (lSGOTT).
Recommended Practice 2003.
Inert Flue Gas Safety Guide.
state and federal regulations.
specific requirements made by owners, operators and state and federal
and Health Considerations
consideration should be given to applicable safety and health
procedures. Considerations should include but are not limited
potential electrostatic and other fire and explosion hazards;
considerations regarding potential personnel exposure (such as exposure
limits, hazard communication, training, and associated protective
clothing and equipment requirements, and work practices); and potential
explosive and toxic hazards associated with a cargo tank's
atmosphere. The physical characteristics of the cargo and
existing operational conditions should be evaluated, and applicable
international, federal, state, and local regulations should be
observed. Safety procedures designated by the employer, the
vessel operator, and other concerned parties should also be
observed. The International Safety Guide/or Oil Tankers and
Terminals and appropriate Oil Companies International Marine Forum
(OCIMF) and API publications should be consulted for additional safety
NOTE: Petroleum vapours and associated substances, including hydrogen
sulphide vapours from "sour" crude, also may involve potential
toxicity. Petroleum vapours with high concentrations of
hydrogen sulphide may cause unconsciousness or death. During
and after the opening of the gauge hatch, stand so that vapour
inhalation is minimized.
NOTE: Harmful vapours or oxygen deficiency cannot be detected safely by
smell, visual inspection, or judgement. Appropriate
precautions should be used for protection against toxic vapours or
oxygen deficiency. Procedures should be developed to provide for
appropriate exposure monitoring, personal protective equipment, and
emergency rescue precautions. When it is necessary, personnel
should have suitable respiratory protection before entering the gauge
site and during the gauging procedure.
Sections of text taken from
API - MPMS Chapter 17 Marine Measurement