Installation, Maintenance, and Repair of Safety Valves (SSV, USV, and BSDV)

API STANDARD 6AV2

SECOND EDITION, AUGUST 2020

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Copyright © 2020 American Petroleum Institute

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Foreword

This standard is under the jurisdiction of the API Subcommittee on Valves and Wellhead Equipment.

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• the term “shall” denotes a minimum requirement to conform to the standard;

  
  

• the term “should” denotes a recommendation or that which is advised but not required to conform to the standard;

• the term “may” is used to express permission or a provision that is optional;

  
  

• the term “can” is used to express possibility or capability.

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This standard shall become effective on the date printed on the cover.

Suggested revisions are invited and should be submitted to the Standards Department, API, 200 Massachusetts Avenue, NW, Suite 1100, Washington DC 2001, standards@api.org.

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, Acronyms, and Abbreviations 1

   1. Terms and Definitions 1

   2. Acronyms and Abbreviations 2

4. Receiving Inspection 3

5. Installation, Maintenance, and Testing 3

   1. General 3

   2. Work Procedures 3

   3. Installation 4

   4. Testing 4

   5. Maintenance 4

6. Repair and Remanufacture 5

   1. Field Repair of Safety Valves 5

   2. Off-site Repair/Remanufacture of Safety Valve 6

7. Testing Procedures 8

   1. General 8

   2. Periodic Operating/Pressure Holding Test 8

   3. Testing After Installation/Field Repairs 10

8. Failure Reporting 12

   1. General 12

   2. Failure Report 12

   3. Reporting Responsibilities 13

9. Documentation Requirements 13

Annex A (informative) Pressure Buildup Calculation 16

Bibliography 26

Figures

1. Safety Valve Field Repair Record Sheet 6

2. Safety Valve Functional Test Datasheet for Installation/Field Repairs 7

3. Safety Valve Functional Test Datasheet for Periodic Testing 10

4. Failure Checklist for Surface Safety Valves and Underwater Safety Valves 15

A.1 Calculation Flow Diagram 18

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Contents

Tables

Page

A.1 Nomenclature 17

vi

Introduction

The safety valve is a valve assembly that closes on loss of power supply. System architecture and power/control

systems for safety valves are addressed in safety system documents such as API 14C.

The surface safety valve (SSV) or underwater safety valve (USV) is typically the second valve in the flow stream of the wellhead and tree. For an offshore surface facility, the boarding shutdown valve (BSDV) is typically the second valve in the flow stream, between an underwater production system and surface facility.

This edition of API 6AV2 contains the following major changes from prior editions:

• Changed the title of the standard to include boarding shutdown valves, which is a new type of safety valve in API 6A, 21st Edition.

  
  

• The term “safety valve” replaced “SSV” and “USV” throughout the document. This term now includes SSV, USV, and BSDV.

— The requirements for off-site repair of safety valves now refer to API 6AR.

— Test and possible repair of the safety valve is addressed. Complete system operation to meet operator and possible

regulatory requirements is not specified.

• Requirements for establishment of product definition by service provider were added.

  
  

• The term “original product definition” and associated requirements were removed.

vii

Installation, Maintenance, and Repair of Safety Valves (SSV, USV and BSDV)

1. Scope

   
   

   This standard provides requirements for installing and maintaining safety valves. Included are requirements for receiving inspection, installation, and maintenance, field and off-site repair, testing procedures with acceptance criteria, failure reporting, and documentation. Power and control systems for safety valves are not included.

   
   

   NOTE 1 “Safety valve” as used in this standard denotes a surface safety valve (SSV), an underwater safety valve (USV), or a boarding shutdown valve (BSDV).

   
   

   NOTE 2 Testing the safety shutdown system and test frequency are outside the scope of this Standard.

   
   

2. Normative References

   
   

   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.

   
   

   API Specification 6A, Specification for Wellhead and Tree Equipment

   
   

   API Standard 6AR, Repair and Remanufacture of Wellhead and Tree Equipment

   
   

   API Standard 18LCM (2017), Product Life Cycle Management System Requirements for the Petroleum and Natural Gas Industries.

   
   

3. Terms, Definitions, Acronyms, and Abbreviations

3.1 Terms and Definitions

For the purposes of this standard, the terms and definitions given in API 6A and the following shall apply.

3.1.1

choked flow

Flow condition in which the fluid velocity and mass-flow rate are insensitive to the pressure drop across the flow

restriction and no phase change occurs.

NOTE Choked flow occurs when the ratio of downstream pressure to upstream pressure is lower than the critical pressure

ratio.

3.1.2

critical pressure ratio

Ratio of pressure downstream of the flow restriction to pressure upstream of the flow restriction below which choked flow occurs.

3.1.3

direct measurement device

Instrument/equipment whose output is the measurement of flow rate (leakage) across the pressure-controlling

components of the safety valves.

3.1.4

indirect measurement method

Use of equipment whose output is the measurement of one or more thermodynamic properties of the fluid moving across the safety valves, and the methodology used to convert the measured quantities into the equivalent flow rate (leakage) across the pressure-controlling components of the safety valves.

1