Flanged Steel Pressure- relief Valves

API STANDARD 526

SIXTH EDITION, APRIL 2009

ERRATA, MAY 2009

ERRATA 2, OCTOBER 2012

Flanged Steel Pressure- relief Valves

Downstream Segment

API STANDARD 526

SIXTH EDITION, APRIL 2009

ERRATA, MAY 2009

ERRATA 2, OCTOBER 2012

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.

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, N.W., Washington, D.C. 20005.

Copyright © 2009 American Petroleum Institute

Foreword

This standard is a purchase specification for flanged steel pressure-relief valves including direct spring-loaded pressure-relief valves and pilot-operated pressure-relief valves.

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, N.W., Washington, D.C. 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 and updated quarterly by API, 1220 L Street, N.W., Washington, D.C. 20005.

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

iii

Contents

Page

1. Scope 1

2. Normative References 1

3. Terms and Definitions 1

4. Responsibility 1

5. Conflicting Requirements 2

6. Orifice Areas and Designations 2

7. Design 3

   1. General 3

   2. Determination of Orifice Area 3

   3. Valve Selection. 3

   4. Dimensions 3

   5. Lifting Levers 3

   6. Special Construction Features 3

8. Material 3

   1. General 3

   2. Spring-loaded Pressure-relief Valves 4

   3. Pilot-operated Pressure-relief Valves 4

9. Inspection and Shop Tests 4

   1. Inspection 4

   2. Set Pressure Test 5

   3. Seat Leakage Test 5

10. Identification and Preparation for Shipment 5

    1. Identification 5

    2. Preparation for Shipment 5

11. Pressure-temperature Tables 5

    1. Materials 5

    2. Temperature Ranges 5

    3. Maximum Inlet Flange Pressure 6

    4. Outlet Pressure Limit 6

Annex A Pressure-relief Valve Nameplate Nomenclature 35

Annex B Pressure-temperature Rating Charts 36

Annex C Bellows Pressure-temperature Requested Rating Factors 39

Annex D Valve Selection Examples 40

Bibliography 43

Tables

1. Standard Effective Orifice Areas and Letter Designations 2

2. Spring Materials 4

3. Spring-loaded Pressure-relief Valves “D” Orifice (Effective Orifice Area = 0.110 in.2) 7

4. Spring-loaded Pressure-relief Valves “E” Orifice (Effective Orifice Area = 0.196 in.2) 8

5. Spring-loaded Pressure-relief Valves “F” Orifice (Effective Orifice Area = 0.307 in.2) 9

6. Spring-loaded Pressure-relief Valves “G” Orifice (Effective Orifice Area = 0.503 in.2) 10

   v

   Page

7. Spring-loaded Pressure-relief Valves “H” Orifice (Effective Orifice Area = 0.785 in.2) 11

8. Spring-loaded Pressure-relief Valves “J” Orifice (Effective Area = 1.287 in.2) 12

9. Spring-loaded Pressure-relief Valves “K” Orifice (Effective Orifice Area = 1.838 in.2) 13

10. Spring-loaded Pressure-relief Valves “L” Orifice (Effective Area = 2.853 in.2) 14

11. Spring-loaded Pressure-relief Valves “M” Orifice (Effective Orifice Area = 3.60 in.2) 15

12. Spring-loaded Pressure-relief Valves “N” Orifice (Effective Orifice Area = 4.34 in.2) 16

13. Spring-loaded Pressure-relief Valves “P” Orifice (Effective Orifice Area = 6.38 in.2) 17

14. Spring-loaded Pressure-relief Valves “Q” Orifice (Effective Orifice Area = 11.05 in.2) 18

15. Spring-loaded Pressure-relief Valves “R” Orifice (Effective Orifice Area = 16.00 in.2) 19

16. Spring-loaded Pressure-relief Valves “T” Orifice (Effective Orifice Area = 26.00 in.2) 20

17. Pilot-operated Pressure-relief Valves “D” Orifice (Effective Orifice Area = 0.110 in.2) 21

18. Pilot-operated Pressure-relief Valves “E” Orifice (Effective Orifice Area = 0.196 in.2) 22

19. Pilot-operated Pressure-relief Valves “F” Orifice (Effective Orifice Area = 0.307 in.2) 23

20. Pilot-operated Pressure-relief Valves “G” Orifice (Effective Orifice Area = 0.503 in.2) 24

21. Pilot-operated Pressure-relief Valves “H” Orifice (Effective Orifice Area = 0.785 in.2) 25

22. Pilot-operated Pressure-relief Valves “J” Orifice (Effective Orifice Area = 1.287 in.2) 26

23. Pilot-operated Pressure-relief Valves “K” Orifice (Effective Orifice Area = 1.838 in.2) 27

24. Pilot-operated Pressure-relief Valves “L” Orifice (Effective Area = 2.853 in.2). 28

25. Pilot-operated Pressure-relief Valves “M” Orifice (Effective Orifice Area = 3.60 in.2) 29

26. Pilot-operated Pressure-relief Valves “N” Orifice (Effective Orifice Area = 4.34 in.2) 30

27. Pilot-operated Pressure-relief Valves “P” Orifice (Effective Orifice Area = 6.38 in.2) 31

28. Pilot-operated Pressure-relief Valves “Q” Orifice (Effective Orifice Area = 11.05 in.2) 32

29. Pilot-operated Pressure-relief Valves “R” Orifice (Effective Orifice Area = 16.00 in.2) 33

30. Pilot-operated Pressure-relief Valves “T” Orifice (Effective Orifice Area = 26.00 in.2) 34

A.1 PRV Nameplate Nomenclature 35

Figures

1. Pressure-temperature Limits 1 to be Used with Table 3 to Table 30 of This Standard 36

2. Pressure-temperature Limits 1 to be Used with Table 3 to Table 30 of This Standard 37

3. Pressure-temperature Limits 1 to be Used with Table 3 to Table 30 of This Standard 37

4. Pressure-temperature Limits 1 to be Used with Table 3 to Table 30 of This Standard 38

5. Pressure-temperature Limits 1 to be Used with Table 3 to Table 30 of This Standard 38

C.1 Bellows Pressure-temperature Rating Factor 39

1. Bellows Pressure-temperature Rating Factor for Example 2 41

2. Pressure-temperature Limits 1 for Example 3 42

Flanged Steel Pressure-relief Valves

1. Scope

   This standard is a purchase specification for flanged steel pressure-relief valves. Basic requirements are given for direct spring-loaded pressure-relief valves and pilot-operated pressure-relief valves as follows:

   • orifice designation and area;

   • valve size and pressure rating, inlet and outlet;

   • materials;

   • pressure-temperature limits;

   • center-to-face dimensions, inlet and outlet.

   
   

   Nameplate nomenclature and requirements for stamping are detailed in Annex A.

   
   

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 Recommended Practice 520 (all parts), Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries

   API Standard 527, Seat Tightness of Pressure Relief Valves

   ASME B16.5 1, Pipe Flanges and Flanged Fittings

   ASME B16.34, Valves-Flanged, Threaded and Welding End

   ASME Boiler and Pressure Vessel Code (BPVC), Section VIII: Pressure Vessels, Division 1 and Division 2

   ASME BPVC, Section II: Materials:

   ASME SA-216, Carbon-Steel Castings Suitable for Fusion Welding for High-Temperature Service

   ASME SA-217, Martensitic Stainless Steel and Alloy Steel Castings for Pressure-Containing Parts, Suitable for High-Temperature Service

   ASME SA-351, Specification for Castings, Austenitic, Austenitic-Ferritic (Duplex), for Pressure-Containing Parts

   ASME SA-494, Specification for Castings, Nickel and Nickel Alloy

   
   

3. Terms and Definitions

   Pressure-relief valve terminology is defined in API 520, Part I.

   
   

4. Responsibility

4.1 The purchaser is primarily responsible for the following:

a) selecting the type of pressure-relief valve and the required pressure-temperature ratings;

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

1