API MPMS Chapter 17.1

These guidelines specify the policy and minimum recommended practices for the manual and automatic measurement, sampling, and accounting for bulk quantities of crude oil (including spiked, blended, and reconstituted crude oil), petroleum products and chemicals that are transported on marine vessels. The activities described in these guidelines include actions by producers, buyers, sellers, terminal operators, vessel owners and their crews, customs authorities, independent inspectors, and other parties with an interest in measurements.

Certain vessel or terminal configurations and cargo characteristics, particularly chemicals, may require extensive procedures and calculation methods not covered in this chapter.

Cargo calculations should be performed independently by the responsible parties and/or by their authorized representatives. The results of the quality determinations and quantity calculations should be compared and any differences resolved without delay. Each party involved in a custody transfer is responsible within his domain for contributing to a reconciliation of vessel and shore quantities and for seeking explanations for any discrepancies.

Any discrepancies relating to quality determination and/or calculated quantities should be recorded and reported to all interested parties. This procedure may be accomplished by issuance of a Letter of Protest or Notice of Apparent Discrepancy. Every effort should be made to resolve discrepancies before the vessel departs.

The independent inspection report for the cargo custody transfer should be issued and distributed promptly.

These procedures are equally valid and applicable for either metric or customary units of measurement, provided that the same types of units are used consistently.