Manual of Petroleum Measurement Standards Chapter 17.9

Vessel Experience Factor (VEF)

El Hydrocarbon Management HM 49

THIRD EDITION, JULY 2019

API MPMS Chapter 17.9/EI HM 49

Vessel Experience Factor (VEF)

Third Edition July 2019

Published jointly by

API

and

ENERGY INSTITUTE LONDON

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Foreword

This publication was prepared jointly by the American Petroleum Institute Committee on Petroleum Measurement and the Energy Institute Hydrocarbon Management Committee.

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Contents

Page

1. Scope 1

2. Normative References 1

   1. General 1

   2. API/EI Documents 1

   3. API Documents 1

   4. EI Documents 1

   5. Other Documents 2

3. Terms and Definitions 2

4. Rationale and Data 4

   1. VEF Rationale 4

   2. Primary and Alternate Methods 4

   3. Measurement Data 4

   4. Data Gathering 5

5. Primary Method Voyage Qualification and Rejection Criteria 5

   1. Number of Voyages 5

   2. Rejected Voyages 5

6. Primary Method Calculation of a VEF 6

7. Use and Application of the VEF 6

   1. General 6

   2. Load and Discharge VEF 6

   3. Compartmental VEF 7

   4. Operations at Multiple Ports or Berths 7

   5. Combination Tow VEF 7

Annex A (informative) Example of a Primary VEF Method Worksheet 8

Annex B (informative) Operations at Multiple Ports or Berths 10

Annex C (informative) Factors Affecting VEF Data 12

Annex D (informative) Measurement Limitations 14

Annex E (informative) The Role of Vessel and Barge Operators 16

Annex F (normative) Alternate Calculation Method 17

Bibliography 21

Figures

1. Load Information 8

2. Discharge Information 8

Tables

1. Example Calculation 1 10

2. Example Calculation 2 10

F.1 Critical Values at the 90 % Probability Level 20

v

Introduction

There are usually differences between the quantity of a cargo measured in a calibrated shore tank or by a custody transfer meter, and the same cargo determined by vessel tank measurements.

For a given vessel, the use of quantity data from many voyages provides an indication of vessel measurement differences as a numerical ratio. This ratio can also include other load and discharge factors. For each voyage, a vessel load ratio (VLR) and vessel discharge ratio (VDR) can be calculated. The mean of the qualifying VLRs or the VDRs over several voyages is called the VEF (VEFL and VEFD for load and discharge, respectively.)

The key aim of this document is to provide a single unambiguous figure for VEFL or VEFD and to remove the possibility of arbitrary inclusion or exclusion of data.

This document was developed by a joint American Petroleum Institute and Energy Institute Hydrocarbon Management Working Group.

Vessel Experience Factor (VEF)

1. Scope

   
   

   This standard provides a recommended practice for the calculation and application of a vessel experience factor (VEF). This standard provides guidelines for data compilation, data maintenance, data validation, and recommendations on the appropriate use of a VEF involving marine vessels.

   
   

   It also provides instruction for parcel tankers, compartmental VEFs, and vessel-to-vessel transfers. The methods are applicable to liquid bulk cargoes including crude oil, petroleum products, chemicals, and liquid petroleum gases.

   
   

2. Normative References

   
   

   1. General

      
      

      The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

      
      

   2. API/EI Documents

      
      

      API MPMS, Chapter 17.5/EI HM 64, Guidelines for Cargo Analysis and Reconciliation

      
      

      API MPMS, Chapter 17.12/HM 51, Procedures for Bulk Liquid Chemical Cargo Inspections

      
      

   3. API Documents

      
      

      API MPMS, Chapter 17.1, Marine Measurement—Guidelines for Marine Cargo Inspection

      
      

      API MPMS, Chapter 17.2, Measurement of Cargoes On-board Tank Vessels

      
      

      API MPMS, Chapter 17.4, Method for the Quantification of Small Volume on Marine Vessels (OBQ/ROB)

      
      

   4. EI Documents

HM 28 1, Procedures for Oil Crude Oil Cargo Inspections Section 1—Crude Oil

HM 29, Procedures for Petroleum Product Cargo Inspections

HM 30, Procedures for Liquefied Petroleum Gas (LPG) Cargo Inspections

HM 68, Procedures for Bulk Liquid Fatty Acid Methyl Esters (FAME) and Blended Biodiesel Cargo Inspections

1 Energy Institute, formerly the Institute of Petroleum, 61 New Cavendish Street, London W1G 7AR, UK, www.energyinst.org.uk.

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