Valve Selection Guide

API RECOMMENDED PRACTICE 615 SECOND EDITION, AUGUST 2016

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Copyright © 2016 American Petroleum Institute

Foreword

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recommended practice.

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1. Scope 1

2. Terms and Definitions 1

3. Considerations for Valve Selection 3

   1. Valve Functions 3

   2. Valve Types 4

   3. Other Considerations 4

4. Primary Valve Types 4

   1. Valves to Stop Flow or to Provide for Equipment Isolation (Block Valves) 4

   2. Valves for Preventing Flow Reversal (Check Valves) 8

   3. Valves for Throttling (Controlling) Flow—Globe Valves 10

5. Service Considerations 10

   1. General 10

   2. Chlorine Service 10

   3. Cryogenic (Low-temperature) Service 11

   4. Hydrofluoric Acid Service 11

   5. Hydrogen Service 11

   6. Oxygen Service 11

   7. Sour Service (Wet H2S Service) 11

   8. Viscous or Solidifying Service 12

6. Valve Material Selection 12

   1. Body Material Selection 12

   2. Valve Trim Selection 12

   3. Seating Surfaces—Soft Seats 13

   4. Stem Sealing—Fugitive Emissions 13

   5. Valve Bonnet Gaskets 14

7. Valve Specific Features and Options 14

   1. Valve Operation 14

   2. Position Indication 14

   3. Hot Tap Valves 14

   4. Double Block Valves for Positive Isolation 14

   5. Double Block-and-Bleed (DB&B) Valves (Single Valve) 15

   6. “Fire Tested” Valves 15

   7. Valve End Connections 15

   8. Cavity Overpressure 15

   9. Flange Shields 15

   10. Valve Purge Connections 16

8. Steps for Valve Selection and Procurement 16

Annex A (informative) Schematic Drawings for Typical Valve Types 17

Annex B (informative) Examples of Typical Valve Purchase Descriptions 34

Bibliography 35

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Figures

1. Typical API 600 Bolted Bonnet Gate Valve—Outside Screw and Yoke 17

2. Typical API 602 Bolted Bonnet Gate Valve 18

3. Typical API 602 Welded Bonnet Gate Valve 18

4. Typical Valve Nomenclature Example from API 603 19

5. Typical Example of Floating Ball Valve—One Piece Body Design Illustrated 20

6. Typical Trunnion Mounted Ball Valves—Two Examples of Split Body Designs 21

7. Typical Sleeve Lined Plug Valve 22

8. Typical Nonlubricated Plug Valve 22

9. Typical Lubricated Plug Valve 23

10. Typical Category A Butterfly Valve 24

A.11a Typical Category B Butterfly Valve—Double Offset Type 24

A.11b Detail of Double Offset Butterfly Valve—Disc and Seats (Seal) 25

1. Detail of Triple Offset Butterfly Valve—Disc and Seats (Seal) 26

2. Typical Single-plate Wafer Check Valve 27

3. Typical Dual-plate Wafer Check Valve 28

4. Typical Flanged Swing Check Valve 29

5. Typical Ball Check Valve—Threaded End 29

6. Typical Piston Check Valve—Threaded End 30

7. Typical Threaded Globe Valve 31

8. Typical Flanged Globe Valve 32

9. Example of API 602 Bellows Stem Seal 33

Introduction

API Recommended Practice (RP) 615 was developed to aid in the selection of valves for the hydrocarbon processing industry (HPI), which includes refineries and petrochemical and chemical plants and the various processes associated with them. This RP may assist in the selection of valves for other industrial processes, such as power or general industry process applications. The task force members who developed this document represent many years of experience in the design and selection of valves and are comprised of professionals from manufacturing, engineering contractors, and end users.

The objective of this RP is to disseminate suggested information on valve selection recommendations as an aid to reduce operational problems and maintenance costs.

Although this RP provides guidance on the selection of valves, the valve specifier or end user is required to pay particular attention to, and is ultimately responsible for, all aspects of the application involving process, metallurgical, and mechanical considerations.

Typical purchase descriptions are provided in the Annex to assist in the complete definition of valve details to help ensure that the correct product is specified for the intended application.

Of prime importance, however, is that this RP is a general guideline for valve selection; the final responsibility is that of the user of this document.

Valve Selection Guide

1. Scope

   
   

   This Recommended Practice (RP) provides general guidance on valve selection for the hydrocarbon processing industry (HPI), which includes refineries and petrochemical, chemical, and liquefied natural gas (LNG) plants and their various associated processes. Selection guidance is provided for valve types covered by ASME B16.34 and API Valve Standards for the Downstream Segment, which include gate, ball, plug, butterfly, check, and globe valves.

   
   

   Modulating control valves and pressure relief valves are outside the scope of this RP.

   
   

2. Terms and Definitions

For the purposes of this document, the following terms and definitions apply.

2.1

abrasive service

Abrasive service is a term used to identify fluids containing particulates that are likely to damage a valve’s pressure boundary or internals through erosion. Fluids containing rust, scale, welding slag, sand, catalyst fines, grit, and hydrocarbon particles (coke) may fall in this category.

2.2

bellows seal

A flexible metal bellows used in place of or in addition to valve stem packing to provide a positive seal against leakage to atmosphere.

2.3

chlorine service

Services containing liquid or vapor chlorine in concentrations higher than 1 ppm as defined in 29 CFR 1910. This does not include water services containing chlorine for pH balancing or as a biocide.

2.4

clean service

Clean service is a term used to identify fluids free from solids or contaminants that could interfere with proper valve operation and/or closure. Clean fluids include most light hydrocarbons, instrument air, nitrogen, water, steam, lube oil, diesel oil, methanol, etc.

2.5

closure member

This refers to the component in the valve that serves to stop flow (internal disc, ball, and plug, for example). A closure member may also be referred to as the valve obturator.

2.6

cryogenic service

The lower end of low temperature service (such as liquefied gas) typically between –163 °C to –196 °C (–261 ° F to

–320 °F).

2.7

dirty service

Dirty service is a general term used to identify fluids with suspended solids that may impair the proper performance of a valve. Detrimental effects of suspended solids on valve performance can be mitigated by minimizing or purging dead zones where suspended solids may accumulate. Dirty service can also be an abrasive service.

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