Subsea Equipment Pressure Ratings

API TECHNICAL REPORT 17TR4 SECOND EDITION, MAY 2016

Special Notes

API publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed.

Neither API nor any of API's employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any information or process disclosed in this publication. Neither API nor any of API's employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights.

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict.

API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obviate the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices.

Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard.

Classified areas may vary depending on the location, conditions, equipment, and substances involved in any given situation. Users of this Technical Report should consult with the appropriate authorities having jurisdiction.

Users of this Technical Report should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations to comply with authorities having jurisdiction. Information concerning safety and health risks and proper precautions with respect to particular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet. All rights reserved.

All rights reserved. No part of this work may be reproduced, translated, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, NW, Washington, DC 20005.

Copyright © 2016 American Petroleum Institute

Foreword

Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent.

This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which this publication was developed should be directed in writing to the Director of Standards, American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director.

Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually by API, 1220 L Street, NW, Washington, DC 20005.

Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standards@api.org.

iii

Contents

1. Scope 1

2. Normative References 1

3. Definitions and Nomenclature 1

   1. Definitions 1

   2. Nomenclature 1

4. Design Issues 2

5. Example Application 3

6. Discussion 5

7. Conclusion 5

Bibliography 7

Figures

1. Example Vessel Under Pressure and Longitudinal Loading 3

2. Loading on Example Vessel Broken into Two Components 4

Subsea Equipment Pressure Ratings

1. Scope

   
   

   The impact of operation in deep water on the pressure rating of equipment is a special concern. The objective of this document is to foster a better understanding of the effects of simultaneous internal and external pressures on the rated working pressure of equipment covered by the scope of API Specification 17D, Subsea Wellhead and Tree Equipment.

   
   

   Additionally, it is intended to provide a high-level overview of issues that should be considered if a user elects to consider differential pressure in their design, especially in components with irregular geometry and with high stress concentrations. It is not intended to serve as a design specification. This document was prepared in response to a request from the API Subcommittee 17 (SC17).

   
   

2. Normative References

   
   

   The following referenced documents are essential when considering the examples outlined in 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 17TR12, Consideration of External Pressure in the Design and Pressure Rating of Subsea Equipment

   
   

   ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 1, “Rules for Construction of Pressure Vessels, Alternative Rules, 2010 Edition

   
   

   ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Rules for Construction of Pressure Vessels, Alternative Rules for Construction of High Pressure Vessels, 2010 Edition

   
   

3. Definitions and Nomenclature

   
   

   1. Definitions

      
      

      For the purposes of this document, the following definition applies.

      
      

      3.1.1

      rated working pressure

      The maximum internal pressure a piece of equipment is designed to contain and/or control. [Source: API Spec 17D, API Spec 6A]

      
      

   2. Nomenclature

A cross-sectional area of vessel wall

Di inside diameter of vessel

Do outside diameter of vessel

d diameter variable, such that Di<d ≤ Do F external applied force

1 ASME International, 3 Park Avenue, New York, New York 10016-5990, www.asme.org.