Crude Oil or Product Tanker Calculations

Survey Documentation -  Determining Fullness of Pipelines between vessels and shore tanks

Physical Characteristics and Fire Considerations WARNING: Personnel who handle petroleum-related substances (as 'well as other chemical materials) should be familiar with their physical and chemical characteristics including potential for fire, explosion, and reactivity and with potential toxicity and health hazards and emergency procedures.  They should comply with individual company safe operating practices and local, state, and federal regulations.  Personnel should be alert to avoid potential sources of ignition and should keep containers of materials closed when not in use.

Page 2 of 4

Pertinent Publications

REFERENCED PUBLICATIONS

The most recent editions of the following recommended practice, guides, and standards are cited in this section of Chapter 17 of the API Manual of Petroleum Measurement Standards (MPMS). 

API

Manual of Petroleum Measurement Standards Chapter 3, Tank Gauging; Section 1A, "Standard Practice for Manual Gauging of Petroleum and Petroleum Products"  Section 1B, "Standard Practice for Level Measurement of Liquid Hydrocarbons in Stationary Tanks by Automatic Tank Gauging" Chapter 7, Temperature Determination.  Chapter 17, Marine Measurement; Section 1, "Guidelines for Marine Cargo Inspection"; Section 2, "Measurement of Cargos On Board Tank Vessels"

RP 2003

Protection Against Ignitions Arising Out of Static. Lightning. and Stray Currents

OCIMF

• International Safety Guide for Oil Tankers and Terminals (ISGOTT)

• Inert Flue Gas Safety Guide

OTHER PERTINENT PUBLICATIONS

The following publications may be consulted for more information.

API

Manual of Petroleum Measurement Standards

• Chapter 4, Proving Systems

• Chapter 5, Metering

• Chapter 8, Sampling

Bull 2509C

Volumetric Shrinkage Resulting from Blending Volatile Hydrocarbons with Crude Oils

Glossary

The following terms are used in this section as indicated by the corresponding explanations.

AGREED TOLERANCE

Before executing any line fill determination procedure, all authorized parties should agree on the amount of difference in measurement that will be accepted when comparing measurements taken before the procedure to measurements taken after the procedure.  This agreement may be in terms of volume rather than level measurement. In this section of API MPMS 17, the term agreed tolerance refers to this agreed-upon span of acceptable difference.

HIGH-POINT BLEED-VALVE METHOD (OR SIGHT-GLASS METHOD)

In this section, the term high-point bleed-valve method (or sight-glass methods refers to checking for the presence of liquid at high-point valves or sight glasses in the designated pipeline system between the shore tank and the vessel berth.

INTERNAL CIRCULATION METHOD

in this section, the term internal circulation method refers to transferring a measured volume of liquid from one shore tank into the same or another shore tank through the pipeline system designated for the transfer of cargo to or from a marine vessel.

LINE DISPLACEMENT METHOD

In this section, the term line displacement method refers to measuring the amount of liquid pumped from a shore tank to a vessel (or from a vessel to a shore tank) through the pipeline system designated for cargo transfer and comparing the measured volume delivered to the measured volume received.

LINE PRESS METHOD (OR LINE PACK METHOD)

In this section, the term line press method (or line pack method) refers to pressurizing the con- tents of the designated pipeline system with a liquid to determine if gases are present.

PIGGING METHOD

In this section, the term pigging method refers to the displacement of the contents of a pipeline system by a tight-fitting wiping device propelled. through the line by gas or liquid, leaving the line full of the propellant.

Terminal Requirements

Nothing in this section, should be construed as overriding safe operating procedures or applicable environmental regulations.

Terminal personnel should designate a tank, a pipeline system (including meters, if used), and the method that will allow the most accurate determination of the quantity received or delivered.  If automatic tank gauges will be used, terminal personnel should provide evidence that they are custody-transfer qualified in accordance with the provisions of API MPMS 3.1B.

The selected line fill verification procedure should be performed immediately before and/or after custody transfer.

Empty shore tanks should not be designated to receive line displacement or internal circulation volumes.

A floating roof should not be in the critical zone.

If the high-point bleed-valve method (or sight- glass method) is selected to determine if a designated pipeline system is full, the valve or sight-glass locations designated for this purpose should be identified.

If either the line displacement method or the internal circulation method is used, records of previous results indicating the effectiveness of these methods should be available.

Data showing the results of the method selected should be available.

Sections of text taken from API - MPMS Chapter 17 Marine Measurement