Verification and Validation of Subsea Connectors

API TECHNICAL REPORT 17TR7 FIRST EDITION, APRIL 2017

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Foreword

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, Abbreviated Terms, and Symbols 2

   1. Terms and Definitions 2

   2. Abbreviated Terms and Symbols 5

4. General 6

   1. Purpose 6

   2. Connector Descriptions 7

   3. Performance Requirements 7

5. Verification Analysis Requirements 8

   1. Purpose 8

   2. Structural Analysis 8

   3. Fatigue Assessment 11

   4. Fatigue Load Design Format and Fatigue Factors 16

6. Validation Testing Requirements 16

   1. General 16

   2. Setup and Monitoring 17

   3. Test Media 17

   4. Hold Periods 18

   5. Acceptance Criteria 18

   6. Post-test Examination 19

   7. Pressure Test Procedure 19

   8. External Load Test Guidelines 19

7. Documentation 20

Annex A (informative) Material Properties for Fatigue Assessment 21

Annex B (informative) Nondestructive Examination 24

Bibliography 26

Figures

1. Normal, Extreme, and Survival Structural Capacity Illustration 9

2. Connector Capacity Chart Example 10

3. Example Stress Transfer Function (STF) 14

Tables

1. Criteria for Elastic Analysis 8

2. Proposed LRFD Load Factors for Elastic-Plastic Analysis 8

3. Proposed Design Fatigue Factor, Df 16

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Introduction

This technical report has been prepared to provide a validation test protocol for subsea connectors for validating the verification analysis. The verification analysis methodology provides guidance to generate connector performance capacity charts.

The intention is to facilitate and complement the connector selection process by ensuring that capacities are determined using common industry design criteria, and to demonstrate leak tightness and structural capacities through testing. This report is not intended to replace sound engineering judgement, nor should it limit additional scope validation tests.

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Verification and Validation of Subsea Connectors

1. Scope

   This Technical Report provides requirements and recommendations for the verification and validation of subsea connectors. It is intended to serve as a common reference for designers, manufacturers, and users to improve the performance assessment of subsea connectors and to improve the reliability and integrity of subsea systems.

   
   

   This technical report is applicable to subsea connectors along the vertical centerline of subsea hardware (i.e. tree, tubing head, tree cap, tree running tool, well control package connectors, and EDP connectors), the subsea wellhead, and the completion/workover riser. The methodology provided herein may also be used in other connector designs. Connectors outboard of the vertical centerline are addressed in API 17R.

   
   

   The scope of this Technical Report includes connectors subjected to structural and pressure loads for wellhead, tree, tubing head, tree cap, tree running tool, and EDP connectors, and is intended to define general performance capacities for API 17D, API 17G, and other applications.

   
   

   In the development of this Technical Report, verification and validation of casing and tubing connectors and welded connectors are recognized as ongoing work. At this time, casing and tubing connectors and welded connectors are not within the scope of this document and are deferred to their applicable specifications.

   
   

   Differential external pressure effects are not within the scope of this document—refer to API 17TR12.

   
   

   Fatigue verification through analysis is included. Fatigue testing of subsea connectors is not a mandatory requirement.

   
   

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 Christmas Tree Equipment

API Specification 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment

API Recommended Practice 17G, Recommended Practice for Completion/Workover Risers

API Technical Report 17TR8, High-pressure High-temperature Design Guidelines

ASME BPVC Section VIII, Rules for Construction of Pressure Vessels Division 2—Alternative Rules

ASME BPVC Section VIII, Rules for Construction of Pressure Vessels Division 3—Alternative Rules for Construction of High Pressure Vessels

BS 7608: Guide to fatigue design and assessment of steel products DNVGL-RP-C203: Fatigue design of offshore steel structures

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