Flanged Steel Pressure-relief Valves

API STANDARD 526

SEVENTH EDITION, SEPTEMBER 2017 ERRATA 1, SEPTEMBER 2018

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Copyright © 2017 American Petroleum Institute

Date of Issue: September 2018

Affected Publication: API Standard 526, Flanged Steel Pressure-relief Valves, September 2017

Errata 1

Table of Contents: Added the following line:

Table of Contents: Changed “Effective Area” to “Effective Orifice Area” in the following lines:

Table of Contents: Changed “Limits” to “Limits1” in the following lines:

Table 3: The boxed sections below reflect changes made to the table:

Table 7: The boxed section below reflects changes made to the table:

Table 8: The title was changed to the following:

Table 8—Spring-loaded Pressure-relief Valves “J” Orifice f

(Effective Orifice Area = 1.287 in.2)

Table 9: The title was changed to the following:

Table 9—Spring-loaded Pressure-relief Valves “K” Orifice f

(Effective Orifice Area = 1.838 in.2)

Table 9: The boxed section below reflects changes made to the table:

Table 10: The title was changed to the following:

Table 10—Spring-loaded Pressure-relief Valves “L” Orifice f

(Effective Orifice Area = 2.853 in.2)

Table 10: The boxed section below reflects changes made to the table:

Table 11: The title was changed to the following:

Table 11—Spring-loaded Pressure-relief Valves “M” Orifice f

(Effective Orifice Area = 3.60 in.2)

Table 12: The title was changed to the following:

Table 12—Spring-loaded Pressure-relief Valves “N” Orifice f

(Effective Orifice Area = 4.34 in.2)

Table 12: The boxed section below reflects changes made to the table:

Table 13: The title was changed to the following:

Table 13—Spring-loaded Pressure-relief Valves “P” Orifice f

(Effective Orifice Area = 6.38 in.2)

Table 14: The title was changed to the following:

Table 14—Spring-loaded Pressure-relief Valves “Q” Orifice f

(Effective Orifice Area = 11.05 in.2)

Table 15: The title was changed to the following:

Table 15—Spring-loaded Pressure-relief Valves “R” Orifice f

(Effective Orifice Area = 16.00 in.2)

Table 15: The boxed sections below reflects changes made to the table:

Table 16: The title was changed to the following:

Table 16—Spring-loaded Pressure-relief Valves “T” Orifice f

(Effective Orifice Area = 26.00 in.2)

Figure B.1: The title was changed to the following:

Figure B.1—Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard

Figure B.2: The title was changed to the following:

Figure B.2—Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard

Figure B.3: The title was changed to the following:

Figure B.3—Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard

Figure B.4: The title was changed to the following:

Figure B.4—Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard

Figure B.5: The title was changed to the following:

Figure B.5—Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard

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iii

Contents

Page

1. Scope 1

2. Normative References 1

3. Terms and Definitions 1

4. Responsibility 2

5. Conflicting Requirements 2

6. Orifice Areas and Designations 2

7. Design 2

   1. General 2

   2. Determination of Orifice Area 2

   3. Valve Selection 2

   4. Dimensions 3

   5. Lifting Levers 3

   6. Special Construction Features 3

   7. Restricted Lift Pressure-Relief Valves 3

8. Material 4

   1. General 4

   2. Spring-loaded Pressure-relief Valves 4

   3. Pilot-operated Pressure-relief Valves 5

9. Inspection and Shop Tests 5

   1. Inspection 5

   2. Set Pressure Test 5

   3. Seat Leakage Test 5

10. Identification and Preparation for Shipment 5

    1. Identification 5

    2. Preparation for Shipment 6

11. Pressure–temperature Tables 6

    1. Materials 6

    2. Temperature Ranges 6

    3. Maximum Inlet Flange Pressure 6

    4. Outlet Pressure Limit 6

Annex A (normative) Pressure-relief Valve Nameplate Nomenclature 35

Annex B (normative) Pressure-temperature Rating Charts 36

Annex C (normative) Bellows Pressure-temperature Requested Rating Factors 39

Annex D (informative) Valve Selection Examples 40

Annex E (informative) Valve Selection Example: Restricted Lift 43

Bibliography 44

Tables

1. Standard Effective Orifice Areas and Letter Designations 3

2. Spring Materials 5

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

   v

   Contents

   Page

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

A.1 PRV Nameplate Nomenclature Table 35

Figures

1. Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard 36

2. Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard 36

3. Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard 37

4. Pressure–temperature Limits1 to be Used with Table 3 to Table 30 of This Standard 37

5. Pressure–temperature Limits1 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 Limits1 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, 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.

1