Pentair Pressure Relief Valve Engineering Handbook Anderson Greenwood, Crosby and Varec Products VALVES & CONTROLS Pentair Pressure Relief Valve Engineering Handbook Forward Technical Publication No. TP-V300 Copyright © 2012 Pentair Valves & Controls. All rights reserved. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without written permission. Pentair Valves & Controls (PVC) provides the information herein in good faith but makes no representation as to its comprehensiveness or accuracy. Individuals using this information in this publication must exercise their independent judgment in evaluating product selection and determining product appropriateness for their particular purpose and system requirements. PVC makes no representations or warranties, either express or implied, including without limitation any warranties of merchantability or fitness for a particular purpose with respect to the information set forth herein or the product(s) to which the information refers. Accordingly, PVC will not be responsible for damages (of any kind or nature, including incidental, direct, indirect, or consequential damages) resulting from the use of or reliance upon this information. Pentair reserves the right to change product designs and specifications without notice. All registered trademarks are the property of their respective owners. Printed in the USA. PVCMC-0296-US-1203 rev 12-2012 Pentair Pressure Relief Valve Engineering Handbook Contents Technical Publication No. TP-V300 Table of Contents Chapter 1 – Introduction 1.1 Chapter 2 – Terminology 2.1 I. General 2.1 II. Types of Devices 2.1 III. Parts of Pressure Relief Devices 2.1 IV. Dimensional Characteristics – Pressure Relief Valves 2.2 V. Operational Characteristics – Pressure Relief Devices 2.3 VI. System Characteristics 2.4 Chapter 3 – Codes and Standards 3.1 I. Introduction 3.3 II. American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code 3.3 III. International Organization for Standardization (ISO) 3.18 IV. European Union Directives 3.22 V. American Petroleum Institute (API) 3.24 VI. National Fire Protection Agency (NFPA) 3.26 VII. National Board of Boiler and Pressure Vessel Inspectors 3.27 Chapter 4 – Design Fundamentals 4.1 I. Introduction 4.3 II. Direct Spring Operated Pressure Relief Valves 4.3 III. Pilot Operated Pressure Relief Valves 4.15 IV. Advantages and Limitations of Valve Types 4.27 Chapter 5 – Valve Sizing and Selection (USCS Units) 5.1 I. Introduction 5.3 II. Gas/Vapor Sizing – Sonic Flow 5.4 III. Gas/Vapor Sizing – Subsonic Flow 5.5 IV. Steam Sizing 5.5 V. Liquid Sizing 5.11 VI. Fire Sizing 5.11 VII. Two-Phase Flow Sizing 5.18 VIII. Noise Level Calculations 5.25 IX. Reaction Forces 5.26 Chapter 6 - Valve Sizing and Selection (Metric Units) 6.1 I. Introduction 6.3 II. Gas/Vapor Sizing – Sonic Flow 6.4 III. Gas/Vapor Sizing – Subsonic Flow 6.5 IV. Steam Sizing 6.6 V. Liquid Sizing 6.11 VI. Fire Sizing 6.13 VII. Two-Phase Flow Sizing 6.15 VIII. Noise Level Calculations 6.23 IX. Reaction Forces 6.24 PVCMC-0296-US-1203 rev 12-2012-US-1203 rev 12-2012 Copyright © 2012 Pentair. All rights reserved. C.1 Pentair Pressure Relief Valve Engineering Handbook Contents Technical Publication No. TP-V300 Table of Contents (continued) Chapter 7 – Engineering Support Information (USCS Units) 7.1 I. Compressibility Factor 7.3 II. Capacity Correction Factor for Back Pressure 7.4 III. Capacity Correction Factor for High Pressure Steam 7.31 IV. Capacity Correction Factor for Viscosity 7.31 V. Capacity Correction Factor for Superheat 7.33 VI. Ratio of Specific Heats and Coefficient C 7.35 VII. Typical Fluid Properties 7.36 VIII. Saturated Steam Pressure Table 7.40 IX. Orifice Area and Coefficient of Discharge for Anderson Greenwood and Crosby Pressure Relief Valves 7.41 X. Equivalents and Conversion Factors 7.48 XI. Capacity Correction Factor for Rupture Disc/Pressure Relief Valve Combination 7.54 Chapter 8 – Engineering Support Information (Metric Units) 8.1 I. Compressibility Factor 8.3 II. Capacity Correction Factor for Back Pressure 8.4 III. Capacity Correction Factor for High Pressure Steam 8.31 IV. Capacity Correction Factor for Viscosity 8.31 V. Capacity Correction Factor for Superheat 8.33 VI. Ratio of Specific Heats and Coefficient C 8.35 VII. Typical Fluid Properties 8.36 VIII. Saturated Steam Pressure Table 8.40 IX. Orifice Area and Coefficient of Discharge for Anderson Greenwood and Crosby Pressure Relief Valves 8.41 X. Equivalents and Conversion Factors 8.48 XI. Capacity Correction Factor for Rupture Disc/Pressure Relief Valve Combination 8.54 PVCMC-0296-US-1203 rev 12-2012 Copyright © 2012 Pentair. All rights reserved. C.2 Pentair Pressure Relief Valve Engineering Handbook Chapter 1 - Introduction Technical Publication No. TP-V300 The primary purpose of a pressure or vacuum relief valve With proper sizing and selection, the user can thus be is to protect life and property by venting process fluid assured that Pentair’s products are of the highest quality from an overpressurized vessel or adding fluid (such as and technical standards in the world of pressure relief air) to prevent formation of a vacuum strong enough to technology. cause a storage tank to collapse. When in doubt as to the proper application of any Proper sizing, selection, manufacture, assembly, testing, particular data, the user is advised to contact the installation, and maintenance of a pressure relief valve are nearest Pentair sales office or sales representative. all critical for optimal protection of the vessel or system. Pentair has a large staff of highly trained personnel Please note that the brand names of pressure relief strategically located throughout the world, who are devices covered (Anderson Greenwood, Crosby, available for your consultation. Whessoe and Varec) are of Pentair manufacture. A Pentair has designed and has available to customers a specific valve brand is selected, according to pressure computer sizing program for pressure relief valves, range, temperature range, valve size, industry application PRV2SIZE (Pressure Relief Valve and Vent Sizing and other applicable factors. Software). The use of this comprehensive program allows This manual has been designed to provide a service to an accurate and documented determination of such Pentair customers by presenting reference data and parameters as pressure relief valve orifice area and technical recommendations based on over 125 years of maximum available flow. pioneering research, development, design, manufacture This sizing program is a powerful tool, yet easy to use. Its and application of pressure relief valves. Sufficient data is many features include quick and accurate calculations, supplied so that an individual will be able to use this user-selected units of measurement, selection of pressure manual as an effective aid to properly size and select relief valve size and style, valve data storage, printed Pentair-manufactured pressure relief devices for specific reports, valve specification sheets and outline drawings. applications. Information covering terminology, standards, Program control via pop-up windows, function keys, codes, basic design, sizing and selection are presented extensive on-line help facilities, easy-to-read formatted in an easy to use format. screens, flagging of errors, and easy editing of displayed The information contained in this manual is offered as a inputs make the program easy to understand and operate. guide. The actual selection of valves and valve products It is assumed that the program user has a general is dependent on numerous factors and should be made understanding of pressure relief valve sizing calculations. only after consultation with qualified Pentair personnel. The program user must remember they are responsible Those who utilize this information are reminded of the for the correct determination of service conditions and the limitations of such publications and that there is no various data necessary for input to the sizing program. substitute for qualified engineering analysis. For download instructions for the latest PRV2SIZE please Pentair pressure relief devices are manufactured in contact your sales representative or factory. accordance with a controlled quality assurance program The information in this manual is not to be used for which meets or exceeds ASME Code quality control ASME Section III nuclear applications. If you need requirements. Capacities of valves with set pressures of assistance with pressure relief valves for ASME 15 psig, or higher, are certified by the National Board of Section III service, please contact our nuclear Boiler and Pressure Vessel Inspectors. These attributes industry experts at 508-384-3121. are assured by the presence of an ASME Code Symbol Stamp and the letters NB on each pressure relief valve nameplate. Lower set pressures are not addressed by either the National Board or ASME; however, capacities at lower set pressures have been verified by actual testing at Pentair’s extensive flow lab facilities. Pentair’s range of pressure relief valves are designed, manufactured, and tested in strict accordance with a quality management system approved to the International Standard Organization’s ISO 9000 quality standard requirements. PVCMC-0296-US-1203 rev 12-2012 Copyright © 2012 Pentair. All rights reserved. 1.1 Pentair Pressure Relief Valve Engineering Handbook Chapter 2 – Terminology Technical Publication No. TP-V300 This chapter contains common and standardized terminology related to pressure relief devices used throughout this handbook and is in accordance with, and adopted from, ANSI/ASME Performance Test Code PTC-25-2008 and other widely accepted practices. I. General F. Pilot operated PRV: a pressure relief valve in which a piston or diaphragm is held closed by system Bench Testing pressure and the holding pressure is controlled by a Testing of a pressure relief device on a test stand using pilot valve actuated by system pressure. an external pressure source with or without an auxiliary lift device to determine some or all of its operating G.