API MPMS 6.3A 2021 PDF

Full title and description

API MPMS Chapter 6.3A — Metering Assemblies: Pipeline and Marine Loading/Unloading Measurement Systems. First edition (July 2021). This chapter of the API Manual of Petroleum Measurement Standards specifies minimum requirements for the design, selection, installation, operation, testing and maintenance of metering assemblies used for pipeline and marine loading/unloading (including FPSO and FSO) single‑phase liquid measurement systems used for commercial and custody‑transfer applications.

Abstract

Chapter 6.3A provides requirements and guidance for metering assemblies that perform pipeline transfer and marine loading/unloading measurements. It focuses on single‑phase liquid systems and addresses metering system components, assembly layout, instrumentation, calibration/proving practices, operational checks, and measures to achieve and document measurement accuracy and integrity for custody‑transfer and commercial transactions. Several measurement types and peripheral equipment are discussed to support reliable, repeatable measurement results; however, specific applications such as LACT systems, multiphase fluids, asphalt, wellhead and subsea measurement are excluded.

General information

• Status: Published (First edition). Listed as an active chapter of API MPMS.
• Publication date: July 1, 2021 (First edition, 2021).
• Publisher: American Petroleum Institute (API).
• ICS / categories: 75 — Petroleum and related technologies; typically categorized under equipment and handling (e.g., 75.180 / 75.200).
• Edition / version: 1st edition (ed. 1, 2021).
• Number of pages: 33 pages (standard print/PDF length reported by distributors).

Scope

This chapter defines minimum requirements for metering assemblies used in pipeline and marine loading/unloading measurement systems handling single‑phase hydrocarbon liquids. It covers design and selection of metering assemblies, recommended instrumentation and secondary devices, installation and layout considerations, calibration and proving procedures appropriate to custody and commercial measurement, operational/maintenance practices, and recordkeeping to support measurement integrity. Exclusions include lease automatic custody transfer (LACT) systems (covered elsewhere), multiphase fluids, asphalt/bitumen-specific methods, wellhead and subsea measurement systems.

Key topics and requirements

• Definition of metering assembly elements for pipeline and marine loading/unloading systems (primary meters, piping, strainers, flow conditioners, valves, bypasses, etc.).
• Design and layout guidance to minimise measurement error (inlet/outlet piping, orientation, access for proving and maintenance, environmental and safety considerations).
• Instrumentation and auxiliary equipment requirements (temperature/pressure measurement, flow computers, sampling provisions, control and alarm systems).
• Calibration, proving and verification practices for custody‑transfer accuracy, including requirements for prover selection, proving procedures, and frequency of verification.
• Operational and maintenance procedures to preserve measurement accuracy (routine checks, drift monitoring, maintenance records, spare parts and testing schedules).
• Quality assurance, documentation and recordkeeping for custody transfer (traceability, test reports, calibration certificates and change control).
• Specific application notes for marine loading/unloading and for installations on floating production/storage/offloading units (FPSO/FSO).
• Clear exclusions and interfaces with related MPMS chapters (e.g., LACT, meter types, volumetric correction and calculation chapters).

Typical use and users

This chapter is used by terminal and marine operators, pipeline operators, FPSO/FSO operators, measurement engineers, custody‑transfer specialists, metering equipment manufacturers, commissioning and maintenance teams, inspection and regulatory bodies, and consultants involved in designing, installing, operating or auditing liquid hydrocarbon metering systems for commercial transfer.

Related standards

Closely related API MPMS chapters and documents include other Chapter 6 sections (for example MPMS 6.1 LACT systems and 6.1A general considerations, 6.2/6.2A for loading‑rack and truck/rail loading, 6.4 aviation fueling metering) plus meter‑type and proving guidance found in MPMS Chapter 5 series, calculation and correction standards in Chapters 11 and 12 (volume correction factors and calculation methods), and other MPMS/ASTM documents referenced for sampling, calibration, and meter performance.

Keywords

API MPMS, Chapter 6.3A, metering assemblies, pipeline metering, marine loading, loading/unloading, FPSO, FSO, custody transfer, flow measurement, meter proving, calibration, instrumentation, petroleum measurement.

FAQ

Q: What is this standard?

A: API MPMS Chapter 6.3A is a chapter of the American Petroleum Institute's Manual of Petroleum Measurement Standards that specifies requirements for metering assemblies used in pipeline and marine loading/unloading measurement systems. It is the first edition published in 2021.

Q: What does it cover?

A: It covers design, selection, installation, operation, proving/calibration, maintenance and recordkeeping practices for single‑phase liquid metering assemblies used in pipeline transfers and marine loading/unloading (including floating units). It explicitly excludes LACT systems, multiphase fluids, asphalt, wellhead and subsea measurement methods.

Q: Who typically uses it?

A: Measurement and process engineers, terminal and pipeline operators, marine terminal owners, FPSO/FSO operators, metering equipment manufacturers, commissioning and maintenance teams, and auditors or regulators involved in custody‑transfer measurement.

Q: Is it current or superseded?

A: This document was published as the first edition in July 2021 and is listed by distributors as the 2021 edition. Users should check with API or their national standards body for the latest status or any amendments before relying on the standard for regulatory or contractual purposes.

Q: Is it part of a series?

A: Yes. It is part of API's Manual of Petroleum Measurement Standards (MPMS), Chapter 6 (Metering Assemblies). Other related Chapter 6 sections and MPMS chapters address LACT systems, loading‑rack and truck/rail systems, specific meter types, proving, and calculation/correction procedures.

Q: What are the key keywords?

A: Metering assemblies, pipeline metering, marine loading/unloading, custody transfer, flow measurement, meter proving, calibration, FPSO, FSO, API MPMS 6.3A.