PROCESS PIPING DESIGN HANDBOOK Volume Two Advanced Piping Design Rutger Botermans and Peter Smith Process Piping Design Handbook Volume Two: Advanced Piping Design Copyright 0 2008 by Gulf Publishing Company, Houston, Texas. All rights reserved. No part of this publication may be reproduced or transmitted in any form without the prior written permission of the publisher. Gulf Publishing Company 2 Greenway Plaza, Suite I020 Houston, TX 77046 I 0 9 8 7 6 5 4 3 2 I ISBN- 10: 1-933762- 18-7 ISBN- 13: 978- 1-933762- 18-0 Library of Congress Cataloging-in-Publication Data Smith, Peter. v. cm. Process piping design handbook. Includes bibliographical references and index. Contents: 1. The fundamentals of piping design / Peter Smith - - 2. Advanced piping design / Rutger Botermans and Peter Smith. ISBN-13: 978-1-933752-04-3 (v. 1 : acid-free paper) ISBN-10: 1-933762-04-7 (v. 1 : acid-free paper) ISBN-13: 978-1-933762-18-0 (v. 2 : acid-free paper) ISBN-10: 1-933752-18-7 (v. 2 : acid-free paper) 1. Pipelines-Design and construction. 2. Piping-Design and construction. 3. Piping-Computer-aided design. 4. Petroleum refineries-Equipment and supplies. I. Botermans, Rutger. 11. Title. TA660.P55S65 2007 621.8'672-dC22 2006038256 Printed in the United States of America Printed on acid-free paper. Text design and composition by TIPS Technical Publishing, Inc. Preface In Volume 1, The Fundamentals of Piping Design, the objective was to arm the reader with the basic “rules” for the design, fabrication, installation, and testing of process and utility piping systems for oil and gas refineries, chemical complexes, and production facilities at both offshore and onshore locations. The objective of Volume 2, Advanced Piping Design, on the same subject, is to look into more detail at the design of process piping sys- tems in specific locations around the various items of process equip- ment that would be typically found in a petrochemical or oil and gas processing facility. For Volume 2, I enlisted the direction and support of Rutger Bot- ermans, from Delft in The Netherlands, who is the author of this title. He wrote the text in a very direct style to avoid any misinterpretation. The bullet point/checklist format allows the reader so see quickly if he or she has considered the point when laying out the piping system. Rutger and his company, Red-Bag, have a great deal to offer the industry; and I look forward to working with him again on other projects. Peter Alspaugh, from Bentley Systems Incorporated, was respon- sible for the CAD-generated drawings and worked under a very tight time frame over the Christmas period. During this particularly busy period, Peter also became a proud father; and I am sure that we all wish Alspaugh junior health and happiness. Finally, my thanks go to Paul Bowers and Richard Beale, Canadian gentlemen who, at very short notice, also during Christmas 2007, car- ried out a peer reading exercise of the original manuscript. Both gen- tlemen are very experienced “pipers,” and their comments were quite constructive and, where possible, incorporated into the book. At this xxiii xxiv Preface very late stage, during the peer reading phase, it was not possible to include some of their ideas. They made some very interesting sugges- tions that would be ideally suited to a “stand-alone” book on the topics that they think need addressing on the subject of piping design. I look forward to the opportunity to work with them again. Volume 2 is not intended to be the finale on the subject of piping design; and because of the nature of the subject, a practitioner never stops learning about the many facets of design, fabrication, erection, inspection, and the testing of piping systems. A process facility is made up of numerous items of equipment, which are used to efficiently change the characteristics of the process flow and change the feedstock initially introduced into the facility. The result is a final product that can be dispatched for distribution to an end user for consumption or further refining. For a process plant to operate effectively and efficiently and there- fore maximize the commercial returns, it is very important that the size, routing, and the valving of process and utility piping systems are optimized to allow them to work efficiently. As with Volume 1, we target the young and intermediate designers and engineers, individuals with a fundamental knowledge of the sub- ject of piping systems who are interesting in expanding their set of technical skills to the next level. This volume covers the various major types of equipment that make up an integrated process facility: Pumps, to move process liquids. Compressors, to move process gases. Heat exchangers, to transfer heat from one product to another. Fired heaters, for direct heating of a product. Tanks, to store process and utility fluids. Columns towers, for distillation of products. Relief systems, to protect the piping system from over pressurization. Pipe racks and tracks, to route and support the piping systems. This second volume is not intended to be a conclusion on the subject of piping, and the reader is recommended to continue to read and research the subject in the future, because the subject is so diverse and suffers no shortage of opinions. --Peter Smith Leiden 2008 Contents List of Figures xi List of Tables xix Foreword xxi Preface xxiii 1 Basic Plant Layout ..................................................... 1 1.1 Introduction 1 1.2 Guidelines for Laying out the Plant 9 2 Pumps .................................................................... 23 2.1 Introduction 23 2.2 TypesofPumps 23 2.3 Types of Drivers 26 2.4 Applicable International Codes 26 2.5 Piping-Specific Guidelines to Layout 43 2.6 Auxiliary Piping 54 2.7 Piping Support and Stress Issues 55 3 Compressors ........................................................... 57 3.1 Introduction 57 3.2 Types of Compressors 57 vi i viii Contents 3.3 Drivers 58 3.4 Applicable International Codes 58 3.5 Piping-Specific Guidelines to Layout 65 4 Exchangers ............................................................. 83 4.1 Introduction 83 4.2 Types of Exchangers 84 4.3 Applicable International Codes 85 4.4 Piping-Specific Guidelines to Layout 92 4.5 Piping Support and Stress Issues 109 5 Fired Heaters ........................................................ 11 1 5.1 Introduction 11 1 5.2 Types of Heaters 111 5.3 Applicable International Codes 116 5.4 Piping-Specific Guidelines to Layout 124 5.5 Operation and Maintenance Influencing Piping Design 131 5.6 Piping Support and Stress Issues 134 6 Tanks .................................................................... 135 6.1 Introduction 135 6.2 Types of Tanks 135 6.3 Applicable International Codes 136 6.4 Piping-Specific Guidelines to Layout 148 7 Columns ............................................................... 165 7.1 Introduction 165 7.2 Internals 165 7.3 Applicable International Code 166 7.4 Piping-Specific Guidelines to Layout 167 Contents ix 8 9 10 Cooling Towers .................................................... 177 8.1 Introduction 177 8.2 Types of Cooling Towers 177 8.3 Inlet and Outlet Piping 178 8.4 Piping Support and Stress Issues 182 Relief Systems ....................................................... 183 9.1 Introduction 183 9.2 Types of Relief Devices 184 9.3 Applicable International Codes 184 9.4 Inlet and Outlet Piping 188 9.5 Piping Support and Stress Issues 195 Pipe Ways ............................................................. 197 10.1 Introduction 197 10.2 Types of Pipe Ways 198 10.3 Piping and Support 199 10.4 Trenched Piping 21 5 10.5 Safety Precautions 216 10.6 Underground Piping 217 Index .................................................................... 21 9 CHAPTER 1 Basic Plant Layout 1.1 Introduction 1.1.1 General No two oil and gas processing facilities are exactly the same; however, they share similar types of process equipment, which perform specific functions. The following are significant items of equipment that are discussed in more detail in this book: Pumps for the transportation of liquids. Compressors for the transportation of compressible fluids. Exchangers for the transfer (exchange) of heat from a heating medium to a fluid. Fired heaters. Columns. Tanks for the storage of compressible and noncompressible fluids. Pipe racks and pipe ways for the routing of process and utility pipework between equipment. To allow the facility to function safely and efficiently, to maximize its commercial profitability, and to result in the optimum layout, the interrelationships among the various types of process equipment must be carefully considered. As the layout is developed, compromises often must be made, and the preference generally is the safer option. All operators of process plants have the same objectives, which is to produce a stable product that meets the end users specification and to maximize the commercial potential of the feedstock for the life of 1 2 Chapter 1-Basic Plant Layout the plant. Even with this common goal operators have subtle differ- ences in the way they have their facilities designed; therefore, the word generally is used liberally in these pages. Generally means that it is common practice, but it is not a mandatory requirement. Listed next are the considerations that have to be reviewed when positioning the equipment during the development of the plant layout. They have not been listed in an order of priority; however, safety is listed at the top as the most significant issue. Safety: fire, explosion, spillage, escape routes for personnel, and access for firefighters. Process flow requirements that result in an efficient plant. Constructability. Segregation of areas for hazardous and nonhazardous materials. Operability and maintainability. Available plot area, geographical limitations. Relationship to adjacent units or other facilities within the plant. Economics. Future expandability. Security: control of access by unauthorized personnel. Meteorological information: climate, prevailing and significant wind direction. Seismic data. Equipment should be laid out in a logical sequence to suit the process flow. Fluid flow requirements (for example, gravity flow sys- tems, pump suction heads, and thermosyphonic systems) often dic- tate relative elevations and necessitate the need for structures to achieve the different elevations. Limitations of pressure or tempera- ture drop in transfer lines decide the proximity of pumps, compres- sors, furnaces, reactors, exchangers, and the like. Equipment piping should be arranged to provide specified access, headroom, and clearances for operation and maintenance. Provision should be made to minimize the disturbance to piping when disman- tling or removing equipment (for example, without removing block valves), including the use of and free access for mobile lifting equip- ment. Pumps should be located in rows adjacent to their pipe ways and near the equipment from which they take suction. The top noz- zles of pumps should be located in the vicinity of overhead steel, such as a beam at the side of the pipe rack, to facilitate piping support. 1.1 Introduction 3 Plant layout requires input from the following discipline engineers; Process. Piping. Mechanical (rotating and vessels). Civil and structural. Instrumentation. HSE (health, safety, and environment). Electrical. Once the relevant information has been sourced, several meetings probably will take place between engineers of these disciplines to develop a plant layout that will satisfy the project’s requirements. As mentioned previously, no two operating companies have exactly the same philosophies; however, they share the same basic common objective, which is to design, construct, and operate a plant that is both safe and economic for the duration of the facility’s operating life. The following lists of points should be considered when evalu- ating the layout of a plant and the relationships among the various items of equipment. They are not necessarily mandatory and could be changed, based on aesthetics, economics, safety, maintenance, or the operator’s experience. 1.1.2 Pumps Locate pumps close to the equipment from which they take suction. This is an important consideration. Consideration should be made to locate pumps under structures or with their motor ends under a pipe rack, allowing an access aisle for mobile handling equipment. Pump suction lines generally are larger than discharge lines, to avoid problems arising from a low net positive suction head (NPSH). End suction with top discharge is the preferable option for pumps, when taking suction directly from tanks or vessels located at grade. Pumps should be arranged in rows with the center line of discharges on a common line. Clearances between pumps or pumps and piping generally are a minimum of 900 mm. 4 Chapter 1-Basic Plant Layout 1.1.3 Compressors It is important to locate reciprocating compressors, anchors, and restraints for pipes belonging to the compressor system on foundations that are independent of any building, structure, or pipe track or rack. This independence gives the associated piping stability and minimizes unnecessary fatigue and possible failure. Spacing between compressors and other equipment varies with the type of machine and its duty. Particular attention must be paid to withdrawal of engine and compressor pistons, cam shaft, crank shaft, and lube oil cooler bundle; cylinder valve maintenance clearance with the least possible obstruction from piping supports. Compressors generally are provided a degree of shelter, that is, a sheets building. Keep the sides up to 8 feet above grade and open and vent the ridge to allow for escape of flammable gas, which might leak from the machines. Certain types of compressors, owing to the height of the mass foundation above grade level, require a mezzanine floor of a grid construction to avoid trapping any gas and for operation and maintenance. 1.1.4 Exchangers Tubular exchangers usually have standard length tubes of 2.5, 4, 5, and 6 m. Whenever possible locate exchangers at grade to facilitate maintenance and tube withdrawal. Two or more shells forming one unit can be stacked or otherwise arranged as indicated on the exchanger specification sheet, which is delineated by the manufacturer. Exchangers with dissimilar service can be stacked, but rarely more than three high, except for fin-tube-type units. Horizontal clearance of at least 900 mm should be left between exchangers or between exchangers and piping. Where space is limited, clearance may be reduced between alternate exchangers, providing sufficient space is left for maintenance and inspection access. Tube bundle removal distance should be a minimum of a tube length plus 900 mm. Minimum removal distance plus 600 mm should be left behind the rear shell cover of floating head exchangers. 1.1 Introduction 5 Where a rear shell cover is provided with a davit, allow clearance for the full swing of the head. Set overhead vapor exchangers or condensers at such elevation that the exchanger is self-draining. Arrange outlets to a liquid hold pot or trap, so that the underside of the exchanger tubes is above the liquid level in the trap. Arrange exchangers so that the fixed end is at the channel end. Vertical exchangers should be set to allow lifting or lowering of the tube bundle. Consult the Vessel Department as to the feasibility of supporting vertical exchangers from associated towers. Space should be left free for tube or bundle withdrawal, with the exchanger channels preferably pointing toward an access area or road. If an exchanger is situated well within the plot, leave a free area and approach for mobile lifting equipment. Air fin exchangers, preferably, should be located in a separate row outside the main equipment row, remote from the central pipe way. Consider locating air fin exchangers over the central pipe way if plot space if very limited. Fired Heaters Fired heaters should be located at least 15 m away from other equipment that could be a source of liquid spillage or gas leakage. To avoid accumulation of flammable liquids, no pits or trenches should be permitted to extend under furnaces or any fired equipment, and if possible, they are to be avoided in furnace areas. Ensure ample room at the firing front of the fired heater for operation and removal of the burners and for the burner control panel, if required. Bottom-floor fired furnaces require adequate headroom underneath the furnace. Wall fired furnaces require an adequate platform width with escape routes at each end of the furnace. Apart from an adequate platform and access to the firing front, other structural attachments and platforms around 6 Chauter 1-Basic Plant Layout furnaces should be kept to a minimum. Peepholes should be provided only where absolutely necessary. Access by means of a stepladder is sufficient. Arrange fired heaters on a common center line, wherever possible. Provide unobstructed space for withdrawal. Operation and maintenance platforms should be wide enough to permit a 1-m clear walkway. Escape ladders should be provided on large heaters. Vertical heaters usually are supplied with stub supporting feet; ensure drawings show adequate supports elevated to the required height. Headroom elevation from the floor level to the underside of heater should be 2.3 m, to provide good firing control operation. Columns Columns usually are self-supporting with no external structures. Circular or segmental platforms with ladders are supported from the shell. The maximum allowable straight run of a ladder before a break platform should not exceed 9 m. The factors influencing column elevation are the provision of a gravity flow system and installation of thermosyphon reboilers. Depending on the plant arrangement, columns may have to be elevated to a height in excess of the normal requirements to allow for headroom clearance from lower-level piping off- takes. The skirt height of all columns or vessels providing suction to pumps, particularly if handling hot or boiling liquids, should be adequate for the pump NPSH requirements. Access platforms should be provided on columns for all valves 3" and above, instrument controllers and transmitters, relief valves, manholes and blinds or spades, and other components that require periodic attention. For access to valves 2" and smaller, indicating instruments, and the like, a ladder is acceptable. 1.1 Introduction 7 Platforms for access to level gauges and controllers should not be provided if underside of supporting steelwork is less than normal headroom clearance from grade. Adjacent columns should be checked, so that platforms do not overlap. For layout, 2.0-2.5 m between shells, depending on insulation, should suffice. Allow a 900 mm minimum clearance between column foundation and the adjacent plinth. Provide clearance for the removal of internal parts and attachments and for davits at top of columns, if relevant. The center line of manholes should be 900 mm above any platform. Horizontal vessels should be located at grade, with the longitudinal axis at a right angle to the pipe way, if possible. Consider saving plot space by changing vessels from the horizontal to the vertical, if possible, and combining vessels together with an internal head (subject to project or process approval). The size and number of access platforms on horizontal vessels should be kept to a minimum and are not to be provided on horizontal vessels or drums when the top of the vessel is 2.5 m or less from the grade. The channel end of vessels provided with internal tubular heaters should face toward an open space. The withdrawal area must be indicated on studies, general arrangements (GAS), and plot plans. Internal agitators or mixers are to be provided with adequate clearance for removal. Removal area must be indicated on studies, GAS, and plot plans Tanks The layout of tanks, as distinct from their spacing, should always take into consideration the accessibility needed for firefighting and the potential value of a storage tank farm in providing a buffer area between process plant and, for example, public roads and houses, for safety and environmental reasons. The location of tankage relative to process units must be such as to ensure maximum safety from possible incidents. 8 Chauter 1-Basic Plant Layout 1.1.8 Pipe Racks and Pipe Ways Ideally, all piping within a process area should be run above grade; however, for many reasons this is not possible. Trenched or buried piping should be avoided but, sometimes, is unavoidable. Pipe racks at higher elevations, using supports, are preferred. Pipe racks may contain one, two, or more layers of pipework; however, triple-layer pipe racks should be limited to very short runs. Run piping external to the process area at grade on sleepers generally 300 mm high. Pipe ways at grade are cheaper but more liable to interfere with access. Locate the largest bore and the heaviest piping as close to stanchions as possible. Lines requiring a constant fall (relief headers) can be run on cantilevers from pipe-rack stanchions or on vertical extensions to pipe-track stanchions. Run the hot line requiring expansion loops on the outside edge of pipe way to permit loops to have greatest width over the pipe way and facilitate nesting. Takeoff elevations from pipe ways should be at a constant elevation, consistent with the range of pipe sizes involved. Change elevation whenever banks of pipes, either on pipe ways at grade or at higher elevations on pipe racks, change direction. Elevations to the underside of pipe racks should be the minimum for operation and mobile maintenance equipment and consistent with allowable clearances. Open pipe trenches may be used between plants where there is no risk of flammable vapors collecting. It sometimes is convenient to run open trenches alongside roadways. (Soil from the trench can be used to build up the road.) Where a pipe way or road changes from a parallel direction, the pipe generally is run beneath the road. Occasionally, it is permissible to run pipes in trenches to overcome a difficult piping problem. Such trenches should be of concrete, drained, and covered. Although trenched piping is to be avoided, due to the expense and hazards associated with open trenches, piping