CONTROL VALVE HANDBOOK Fifth Edition Emerson Automation Solutions Flow Controls Marshalltown, Iowa 50158 USA Sorocaba, 18087 Brazil Cernay, 68700 France Dubai, United Arab Emirates Singapore 128461 Singapore Neither Emerson, Emerson Automation Solutions, nor any of their affiliated entities assumes responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use, and maintenance of any product remains solely with the purchaser and end user. The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are governed by our terms and conditions, which are available upon request. We reserve the right to modify or improve the designs or specifications of such products at any time without notice. Fisher is a mark owned by one of the companies in the Emerson Automation Solutions business unit of Emerson Electric Co. Emerson and the Emerson logo are trademarks and service marks of Emerson Electric Co. All other marks are the property of their respective owners. © 2005, 2019 Fisher Controls International LLC. All rights reserved. D101881X012/ Sept19 Preface Control valves are an increasingly vital component of modern manufacturing around the world. Properly selected and maintained control valves increase efficiency, safety, profitability, and ecology. The Control Valve Handbook has been a primary reference since its first printing in 1965. This fifth edition presents vital information on control valve performance and the latest technologies. Chapter 1 offers an introduction to control valves, including definitions for common control valve and instrumentation terminology. Chapter 2 develops the vital topic of control valve performance. Chapter 3 covers valve and actuator types. Chapter 4 describes digital valve controllers, analog positioners, boosters, and other control valve accessories. Chapter 5 is a comprehensive guide to selecting the best control valve for an application. Chapter 6 addresses the selection and use of special control valves. Chapter 7 explains desuperheaters, steam conditioning valves, and turbine bypass systems. Chapter 8 details typical control valve installation and maintenance procedures. Chapter 9 contains information on control valve standards and approval agencies across the world. Chapter 10 identifies isolation valves and actuators. Chapter 11 covers discrete automation. Chapter 12 discusses various process safety instrumented systems. Chapter 13 provides useful tables of engineering reference data. Chapter 14 includes piping reference data. Chapter 15 is a handy resource for common conversions. The Control Valve Handbook is both a textbook and a reference on the strongest link in the control loop: the control valve and its accessories. This book includes extensive and proven knowledge from leading experts in the process control field, including contributions from the ISA. Table of Contents Control Valve Handbook | Table of Contents Chapter 1: Introduction to Control Valves ............................................. 14 1.1 What is a Control Valve? ..............................................................................15 1.2 Sliding-Stem Control Valve Terminology .....................................................15 1.3 Rotary Control Valve Terminology ...............................................................21 1.4 Control Valve Functions and Characteristics Terminology ............................23 1.5 Process Control Terminology .......................................................................25 Chapter 2: Control Valve Performance .................................................. 32 2.1 Process Variability .......................................................................................33 2.1.1 Deadband ................................................................................................................ 35 2.1.1.1 Causes of Deadband .........................................................................................................35 2.1.1.2 Effects of Deadband .........................................................................................................36 2.1.1.3 Performance Tests ............................................................................................................36 2.1.1.4 Friction ............................................................................................................................36 2.1.2 Actuator and Positioner Design ................................................................................ 37 2.1.3 Valve Response Time ................................................................................................ 38 2.1.3.1 Dead Time .......................................................................................................................38 2.1.3.2 Dynamic Time ..................................................................................................................38 2.1.3.3 Solutions ..........................................................................................................................39 2.1.3.4 Supply Pressure ................................................................................................................40 2.1.3.5 Minimizing Dead Time .....................................................................................................40 2.1.3.6 Valve Response Time ........................................................................................................41 2.1.4 Valve Type and Characterization ............................................................................... 41 2.1.4.1 Installed Gain ...................................................................................................................43 2.1.4.2 Loop Gain ........................................................................................................................43 2.1.4.3 Process Optimization .......................................................................................................44 2.1.5 Valve Sizing .............................................................................................................. 45 2.2 Economic Results ........................................................................................46 2.3 Summary ....................................................................................................48 Chapter 3: Valve and Actuator Types ..................................................... 50 3.1 Control Valve Styles ....................................................................................51 3.1.1 Globe Valves ............................................................................................................ 51 3.1.1.1 Single-Port Valve Bodies ...................................................................................................51 3.1.1.2 Post- and Port-Guided Valve Bodies ...................................................................................52 3.1.1.3 Cage-Style Valve Bodies ....................................................................................................52 3.1.1.4 Double-Ported Valve Bodies ..............................................................................................53 3.1.1.5 Three-Way Valve Bodies....................................................................................................53 3.1.2 Sanitary Valves ........................................................................................................ 54 3.1.3 Rotary Valves ........................................................................................................... 54 3.1.3.1 Butterfly Valve Bodies .......................................................................................................54 3.1.3.2 Segmented Ball Valve Bodies ............................................................................................55 5 Control Valve Handbook | Table of Contents 3.1.3.3 High-Performance Butterfly Valve Bodies ..........................................................................55 3.1.3.4 Eccentric Plug Valve Bodies ...............................................................................................56 3.1.3.5 Full-Port Ball Valve Bodies .................................................................................................57 3.1.3.6 Multi-Port Flow Selector ...................................................................................................57 3.2 Control Valve End Connections ...................................................................57 3.2.1 Screwed Pipe Threads .............................................................................................. 57 3.2.2 Bolted Gasketed Flanges ........................................................................................... 58 3.2.3 Welded End Connections .......................................................................................... 58 3.2.4 Other Valve End Connections ................................................................................... 59 3.3 Valve Body Bonnets .....................................................................................59 3.3.1 Extension Bonnets...................................................................................................