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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Eliminate or reduce unwanted emissions with the piping engineering techniques and strategies contained in this book Piping Engineering: Preventing Fugitive Emission in the Oil and Gas Industry is a practical and comprehensive examination of strategies for the reduction or avoidance of fugitive emissions in the oil and gas industry. The book covers key considerations and calculations for piping and fitting design and selection, maintenance, and troubleshooting to eliminate or reduce emissions, as well as the various components that can allow for or cause them, including piping flange joints. The author explores leak detection and repair (LDAR), a key technique for managing fugitive emissions. He also discusses piping stresses, like principal, displacement, sustained, occasional, and reaction loads, and how to calculate these loads and acceptable limits. Various devices to tighten the bolts for flanges are described, as are essential flange fabrications and installation tolerances. The book also includes: * Various methods and calculations for corrosion rate calculation, flange leakage analysis, and different piping load measurements * Industry case studies that include calculations, codes, and references * Focuses on critical areas related to piping engineering to prevent emission, including material and corrosion, stress analysis, flange joints, and weld joints * Coverage of piping material selection for offshore oil and gas and onshore refineries and petrochemical plants Ideal for professionals in the oil and gas industry and mechanical and piping engineers, Piping Engineering: Preventing Fugitive Emission in the Oil and Gas Industry is also a must-read resource for environmental engineers in the public and private sectors.
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Piping Engineering
Preventing Fugitive Emission in the Oil and Gas Industry
Karan Sotoodeh
Hovik
Norway
This edition first published 2023
© 2023 John Wiley & Sons, Inc.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.
The right of Karan Sotoodeh to be identified as the author of this work has been asserted in accordance with law.
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Limit of Liability/Disclaimer of Warranty
In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of experimental reagents, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each chemical, piece of equipment, reagent, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.
A catalogue record for this book is available from the Library of Congress
Hardback ISBN: 9781119852032; ePub ISBN: 9781119852056; ePDF ISBN: 9781119852049; oBook ISBN: 9781119852063
Cover image: © Shazrul Edwan/Shutterstock
Cover design by Wiley
Set in 9.5/12.5pt STIXTwoText by Integra Software Services Pvt. Ltd, Pondicherry, India
Contents
Cover
Title page
Copyright
Author Biography
1 An Introduction to Fugitive Emission, Piping Engineering, and LDAR
1.1 Introduction to Fugitive Emission
1.2 Introduction to Piping Engineering
1.3 Causes of Piping Failure and Leakage
1.4 Leak Detection and Repair (LDAR)
1.4.1 Composite Repair
1.4.2 Mechanical Clamp Repair
1.4.3 Welded Leak Box Repair
1.4.4 External Weld Overlay
1.4.5 Sleeve Repair
1.5 Questions and Answers
Further Readings
2 Piping Pressure Design to Prevent Leakage and Emission
2.1 Introduction to Piping Design
2.2 Piping and Pipeline Wall Thickness Calculation
2.2.1 Piping Wall Thickness Calculation as per ASME B31.3
2.2.2 Pipeline Wall Thickness Calculation
2.3 Pipe Fittings Wall Thickness/Pressure Rating
2.4 Flange Pressure Rating and Thickness Selection
2.5 Questions and Answers
Further Readings
3 Piping Stress Analysis to Prevent Operational Failure
3.1 Introduction to Piping Stress Analysis
3.2 Principal Piping Stresses
3.3 Sustained Loads
3.4 Occasional Loads
3.4.1 Earthquake and Blast Load
3.4.2 Wind Load
3.5 Displacement Stress
3.5.1 Stress Intensification Factor (SIF)
3.6 Piping Reaction Forces
3.6.1 Pressure Safety/Relief Valve Reaction Force
3.6.2 Slug Flow Reaction Force
3.6.3 Water Hammering Load Calculation
3.7 Conclusion
3.8 Questions and Answers
Further Readings
4 Piping Flange Joints
4.1 Introduction
4.2 Flanges
4.2.1 Flange Standards
4.2.2 Flange Types
4.2.3 Flange Faces
4.2.4 Flange Surface (Face) Finish
4.2.5 Flange Identification
4.2.6 Flange Installation
4.3 Gaskets
4.3.1 Nonmetallic Flat Gaskets
4.3.2 Semimetallic Gaskets
4.3.3 Metallic Gaskets
4.4 Bolting (Bolts and Nuts)
4.4.1 Bolt Tightening
4.5 Mechanical Joints (Hubs and Clamps)
4.6 Compact Flanges
4.7 Questions and Answers
Appendix A
Further Readings
5 Piping Flange Joint Calculations
5.1 Introduction
5.2 Bolt Length Determination and Calculation
5.2.1 Long Bolt Length Calculation for Wafer Body Valves
5.2.2 Long Bolt Length Calculation for Flanges with Line Blanks
5.3 Flange Leakage Analysis
5.3.1 Bolting Characteristics
5.3.2 Gasket Behavior
5.3.3 Combination of Bolt Loads and Gasket Reaction
5.3.4 Flange Loading
5.3.5 Pressure Equivalent Method
5.4 Questions and Answers
Appendix A
Further Readings
6 Piping Material Selection and Corrosion Prevention
6.1 Introduction
6.2 Onshore Pipeline
6.2.1 Onshore Pipeline Material Selection
6.2.2 External Corrosion
6.2.3 Pipeline External Corrosion Protection
6.2.4 Pipeline Internal Corrosion Types and Mitigation
6.3 Onshore Piping
6.3.1 Onshore Piping Material Selection
6.3.2 Onshore Piping Corrosion Types
6.4 Offshore Piping
6.4.1 Offshore Piping Material Selection
6.4.2 Offshore Piping Corrosion Study
6.5 Questions and Answers
Further Readings
7 Piping Component Selection and Identification
7.1 Introduction and Overview
7.2 Pipe
7.3 Pipe Fittings
7.3.1 Fittings for Piping Route Change
7.3.2 Fittings for Pipe Size Change
7.3.3 Fittings for Branching
7.3.4 Fittings for Pipe Termination or Blinding
7.4 Questions and Answers
Further Readings
8 Piping Fabrication, Inspection, and Testing
8.1 Introduction and Overview
8.2 Fabrication, Assembly, and Erection
8.2.1 Welding
8.3 Inspection
8.3.1 Introduction
8.3.2 Welding Inspection
8.4 Piping Pressure Test
8.4.1 Test Media
8.4.2 Test Preparation
8.4.3 Test Implementation
8.5 Questions and Answers
Further Readings
Index
End User License Agreement
List of Illustrations
Chapter 1
Figure 1.1 Fugitive emission...
Figure 1.2 Fugitive emission...
Figure 1.3 Fugitive emission...
Figure 1.4 Effects of global...
Figure 1.5 Pressure flow...
Figure 1.6 Typical engineering...
Figure 1.7 Typical costs...
Figure 1.8 Typical field...
Figure 1.9 Types of flange...
Figure 1.10 Flange misalignment...
Figure 1.11 Gasket failures due...
Figure 1.12 Gasket sealing failure...
Figure 1.13 Corrosion of flange...
Figure 1.14 Flange joint disconnection...
Figure 1.15 Dent in piping.
Figure 1.16 Gouges in piping.
Figure 1.17 Stress cracking of a pipe...
Figure 1.18 Burst elbow in a piping...
Figure 1.19 Causes of piping failure...
Figure 1.20 LDAR steps and flow chart...
Figure 1.21 Corroded piping.
Figure 1.22 Composite wrapping around...
Figure 1.23 Mechanical clamp...
Figure 1.24 Clamp installation...
Figure 1.25 Welded leak box...
Figure 1.26 External weld...
Figure 1.27 Type B sleeve...
Figure 1.28 Flange alignment...
Figure 1.29 Piping failure...
Figure 1.30 Bolting problem...
Chapter 2
Figure 2.1 Part of the West-East...
Figure 2.2 Piping system...
Figure 2.3 Piping failure...
Figure 2.4 Longitudinal weld...
Figure 2.5 A mandrel and a piece of seamless pipe.
Figure 2.6 Creep in a steam line.
Figure 2.7 Liquid pipeline...
Figure 2.8 Pipe thread...
Figure 2.9 National pipe...
Figure 2.10 Electrical resistance...
Figure 2.11 Spiral wound...
Figure 2.12 A 90...
Figure 2.13 A tee...
Figure 2.14 A lateral...
Figure 2.15 Using 2...
Figure 2.16 Cap welded...
Figure 2.17 An olet...
Figure 2.18 Section of...
Figure 2.19 Bevel end...
Figure 2.20 Making a...
Figure 2.21 Hot extrusion...
Figure 2.22 A tee...
Figure 2.23 A wrought...
Figure 2.24 A socket...
Figure 2.25 A coupling...
Figure 2.26 Flange thickness...
Figure 2.27 Flanged fittings...
Figure 2.28 Flange schematics...
Figure 2.29 Correlation between...
Figure 2.31 A piping...
Figure 2.32 A lap...
Figure 2.30 Weld Olet...
Chapter 3
Figure 3.1 Hoop and...
Figure 3.2 Radial stress...
Figure 3.3 Pipe burst...
Figure 3.4 Radial, axial...
Figure 3.5 Rest support...
Figure 3.6 Maximum bending...
Figure 3.7 A pipe...
Figure 3.8 A pipe...
Figure 3.9 Ice load...
Figure 3.10 A 12...
Figure 3.11 Relationship between...
Figure 3.12 Two piping...
Figure 3.13 Flange weld...
Figure 3.14 Significant damage...
Figure 3.15 Piping joint...
Figure 3.16 Piping arrangement...
Figure 3.18 Expansion loops...
Figure 3.19 A rubber...
Figure 3.17 Pipe deflection...
Figure 3.20 Change of...
Figure 3.21 Distance of...
Figure 3.22 Piping expansion...
Figure 3.23 SIF values...
Figure 3.24 SIF values...
Figure 3.25 Buttweld connection...
Figure 3.26 Eccentric and...
Figure 3.27 Pressure relief...
Figure 3.28 Fluid pressure...
Figure 3.29 Slug flow...
Figure 3.30 Swing check...
Figure 3.31 Water hammering...
Figure 3.32 Water hammering...
Figure 3.33 Load classification...
Figure 3.34 Pipe split...
Figure 3.35 PSV on...
Chapter 4
Figure 4.1 A flange...
Figure 4.2 Bolt circle...
Figure 4.3 Flange bolting...
Figure 4.4 Different dimensions...
Figure 4.5 A weld...
Figure 4.6 A socket...
Figure 4.7 A socket...
Figure 4.8 Slip on...
Figure 4.9 A lap...
Figure 4.10 A threaded...
Figure 4.11 A blind...
Figure 4.12 An orifice...
Figure 4.13 An orifice...
Figure 4.14 Smooth finish...
Figure 4.15 Flat face...
Figure 4.16 A ring...
Figure 4.17 Raised face...
Figure 4.18 RTJ flanges...
Figure 4.19 Comparing oval...
Figure 4.20 Gasket sealing...
Figure 4.21 Comparing API...
Figure 4.22 R, RX...
Figure 4.23 Tongue and...
Figure 4.24 Male and...
Figure 4.25 Roughness illustration...
Figure 4.26 Damaging the...
Figure 4.27 Uncoated nut...
Figure 4.28 Bolt plugs...
Figure 4.29 Effect of...
Figure 4.30 Flange faces...
Figure 4.31 Flange faces...
Figure 4.32 Misalignment of...
Figure 4.33 Misalignment of...
Figure 4.34 Angular misalignment...
Figure 4.35 Correct flange...
Figure 4.36 Flange installation...
Figure 4.37 Maximum misalignment...
Figure 4.38 Flat rubber...
Figure 4.39 Semimetallic spiral...
Figure 4.40 Marking on...
Figure 4.41 Spiral wound...
Figure 4.42 Acceptable graphite...
Figure 4.43 Rejected spiral...
Figure 4.44 Metal jacket...
Figure 4.45 Double metal...
Figure 4.46 RTJ gasket...
Figure 4.47 A stud...
Figure 4.48 Comparing fine...
Figure 4.50 Washer installation...
Figure 4.49 Bolts and...
Figure 4.51 Manual wrench...
Figure 4.52 Manual and...
Figure 4.53 Flange bolt...
Figure 4.54 Lubrication of...
Figure 4.55 Typical crisscross...
Figure 4.56 Bolt tensioning...
Figure 4.57 Pulling out...
Figure 4.58 Tightening a...
Figure 4.59 Space and...
Figures 4.60 and 4.61 Hub and clamp assembly. (Courtesy: SFF/Galperti).
Figure 4.62 Inappropriate seal...
Figure 4.63 Proper seal...
Figure 4.64 Size comparison...
Figure 4.65 Compact flange...
Figure 4.66 Flange inspection...
Figure 4.67 Flange inspection...
Figure 4.68 Bolt tightening...
Figure 4.69 Bolt tightening...
Chapter 5
Figure 5.1 Lack of...
Figure 5.2 Typical flange...
Figure 5.3 A wafer...
Figure 5.4 Long stud...
Figure 5.5 Stud bolts...
Figure 5.6 Stud bolt...
Figure 5.7 A stud...
Figure 5.8 Basic flange...
Figure 5.9 Wafer type...
Figure 5.10 Wafer butterfly...
Figure 5.11 Spade, spacer...
Figure 5.12 8ʺ...
Figure 5.13 8ʺ...
Figure 5.14 Flange rotation...
Figure 5.15 Flange disconnection...
Figure 5.16 Flange bolt...
Figure 5.17 Stress-strain...
Figure 5.18 Typical gasket...
Figure 5.19 Bolt load...
Figure 5.20 Applied flange...
Figure 5.21 Flange symbols...
Figure 5.22 12ʺ...
Chapter 6
Figure 6.1 Offshore platform...
Figure 6.2 Onshore refinery...
Figure 6.3 Pitting corrosion...
Figure 6.4 A tanker...
Figure 6.5 Upheaval buckling...
Figure 6.6 Chloride stress...
Figure 6.7 Coal tar...
Figure 6.8 Pipe with...
Figure 6.9 Cathodic protection...
Figure 6.10 Carbon dioxide...
Figure 6.11 Carbon dioxide...
Figure 6.12 HIC crack...
Figure 6.13 Hydrogen blistering...
Figure 6.14 Schematic of...
Figure 6.15 SSC regions...
Figure 6.16 High seawater...
Figure 6.17 Crevice corrosion...
Figure 6.18 Galvanic corrosion...
Figure 6.19 Galvanic series...
Chapter 7
Figure 7.1 90- and...
Figure 7.2 Long and...
Figure 7.3 Pipe return...
Figure 7.4 Pipe bending...
Figure 7.5 A 16...
Figure 7.6 Miter bends...
Figure 7.7 Eccentric and...
Figure 7.8 Eccentric reducer...
Figure 7.9 Pipe size...
Figure 7.10 Correct choice...
Figure 7.11 Correct installation...
Figure 7.12 Eccentric and...
Figure 7.13 Swage nipples...
Figure 7.14 Female threaded...
Figure 7.15 Weldolet welded...
Figure 7.16 A sweepolet...
Figure 7.17 A sockolet...
Figure 7.18 Threadolets...
Figure 7.20 A flangeolet...
Figure 7.21 Reinforcement pads...
Figure 7.22 A reinforcement...
Figure 7.23 Pipe-to...
Figure 7.24 Wrought cap...
Figure 7.25 A cap...
Figure 7.26 Blinding the...
Figure 7.27 A plug...
Figure 7.28 Swage nipple...
Chapter 8
Figure 8.1 Maximum allowable...
Figure 8.2 Pipe spools...
Figure 8.3 Heat affected...
Figure 8.4 Distance between...
Figure 8.5 Buttweld connection...
Figure 8.6 Fillet welds...
Figure 8.7 Welding positions...
Figure 8.8 Examples of...
Figure 8.9 Cracks in...
Figure 8.10 Different welding...
Figure 8.11 Transverse crack...
Figure 8.12 Porosity in...
Figure 8.13 Spatter in...
Figure 8.14 Welding misalignment...
Figure 8.15 Overlap and...
Figure 8.16 Underfill (lack...
Figure 8.17 Overfill (excessive...
Figure 8.18 Root and...
Figure 8.19 Lack of...
Figure 8.20 Lack of...
Figure 8.21 Welding visual...
Figure 8.22 Magnetic particle...
Figure 8.23 Liquid penetration...
Figure 8.24 Porosity in...
Figure 8.25 Ultrasonic examination...
Figure 8.26 Hydrostatic pressure...
Figure 8.27 Hydrotest of...
Figure 8.28 An arc...
Figure 8.29 Fabrication of a pipe spool.
List of Tables
Chapter 1
Table 1.1 Equipment and component...
Chapter 2
Table 2.1 Longitudinal weld joint...
Table 2.2 Weld joint strength...
Table 2.3 Material coefficient as...
Table 2.4 Excerpt from Table...
Table 2.5 14ʺ Piping...
Table 2.6 14ʺ Piping...
Table 2.7 Weld joint factor...
Table 2.8 Yield and allowable...
Table 2.9 Basic dimensions of...
Table 2.10 10ʺ and...
Table 2.11 Basic design factor...
Table 2.12 18ʺ and...
Table 2.13 Correlation of the...
Table 2.14 Socket weld fitting...
Table 2.15 Size range of...
Table 2.16 Pressure-temperature rating...
Table 2.17 Pressure–temperature...
Table 2.18 List of material...
Table 2.19 Typical tee branch...
Table 2.20 Pressure-temperature rating...
Table 2.21 Dimensions of flange...
Table 2.22 Dimensions of flange...
Table 2.23 Dimensions of flange...
Chapter 3
Table 3.1 20ʺ piping...
Table 3.2 Allowable yield and...
Table 3.3 12ʺ standard...
Table 3.4 A 12ʺ...
Table 3.5 Allowable stress values...
Table 3.6
Seismic or
...
Table 3.7 Stress reduction factor...
Table 3.8 Thermal ASTM A53...
Table 3.9 Thermal coefficient of...
Table 3.10 Modulus of elasticity...
Table 3.11 Stress intensification factor...
Table 3.12 Stress intensification factor...
Table 3.13 Flexibility factor and...
Table 3.14 Definitions of parameters...
Table 3.15 Provided data for...
Table 3.16 Outside diameter and...
Table 3.17 Flexibility factor,...
Table 3.18 Thickness of an...
Chapter 4
Table 4.1 Flange tightness class...
Table 4.2 Dimensions of large...
Table 4.3 Dimensions of large...
Table 4.4 Comparing a 30...
Table 4.5 Dimensions of Series...
Table 4.6 Dimensions of Series...
Table 4.7 Stub end dimensions...
Table 4.8 R style gasket...
Table 4.9 Maximum hardness values...
Table 4.10 Heavy hexagonal nut...
Table 4.11 Bolt and nut...
Table 4.12 Nut factors (dimensionless...
Table 4.13 G-Lok hub...
Table 4.14 Stud bolt and...
Table 4.15 Metric and inch...
Chapter 5
Table 5.1 Stud bolt diameter...
Table 5.2 Approximate distance values...
Table 5.3 Flange and bolting...
Table 5.4 Wafer butterfly valve...
Table 5.5 Wafer butterfly valve...
Table 5.7 CL150 flange dimensions...
Table 5.6 Wafer check valve...
Table 5.8 Spectacle blind size...
Table 5.9 Male RTJ CL600...
Table 5.10 CL600 raised face...
Table 5.11 Bolting information for...
Table 5.12 Chemical composition of...
Table 5.13 Gasket factor m...
Table 5.14 Gasket factor...
Table 5.15 Pressure-temperature rating...
Table 5.16 Values of moment...
Table 5.17 Stud bolt and...
Table 5.18 Metric and inch...
Chapter 6
Table 6.1 Final corrosion rate...
Table 6.2 Stainless steel grades...
Table 6.3 Stainless steel grades...
Table 6.4 Material selection summery...
Table 6.5 ASTM Material grade...
Table 6.6 Environmental and material...
Table 6.7 6MO and nickel...
Table 6.8 Mechanical properties of...
Table 6.9 Chemical properties percentage...
Table 6.10 Austenitic stainless-steel...
Chapter 7
Table 7.1 A branch table...
Table 7.2 Branch table...
Table 8.2 Example of welding...
Table 8.3 Definition of NDT...
Table 8.4 NDT extension as...
Guide
Cover
Title page
Copyright
Table of Contents
Author Biography
Begin Reading
Index
End User License Agreement
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Author Biography
Karan Sotoodeh, an Iranian author and engineer, previously worked for Baker Hughes as a senior/lead valve and actuator engineer in the subsea oil and gas industry. He earned a doctor of philosophy in safety and reliability in mechanical engineering from the University of Stavanger in 2021. Karan Sotoodeh has nearly 16 years of experience in the oil and gas industry, mainly with valves, piping, actuators, and material engineering. He has written eight books about piping, valves, actuators, corrosion, and material selection and more than 30 papers in peer-reviewed journals. He has also been selected in international conferences in USA, Germany, and China to lecture on valves, actuators, and piping. Karan Sotoodeh has worked with many valve suppliers in Europe in countries such as UK, Italy, France, Germany, and Norway. He loves traveling, running, swimming, and spending time in nature.
1 An Introduction to Fugitive Emission, Piping Engineering, and LDAR
1.1 Introduction to Fugitive Emission
Fugitive emission is defined as the unintentional and undesirable emission, leakage, or discharge of gases or vapors from pressure-containing equipment or facilities, and from components inside industrial plants, such as valves, piping flanges, pumps, storage tanks, compressors, etc. Fugitive emission is also known as leak or leakage. The term “fugitive” is used because these emissions are not taken into account and calculated during the design of the equipment and components.
Volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) are considered the main fugitive emission compounds. HAPs, also referred to as toxic air pollutants, are those that can cause serious health problems such as cancer. The Environmental Protection Agency (EPA) has detected 187 types of HAPs, such as lead, ozone, nitrogen dioxide, etc. VOCs are organic compounds or chemicals that have high vapor pressure at ordinary room temperature and low water stability. Many VOCs are synthetic chemicals used in industry. VOCs are typically emitted as gasses from solids or liquids. Methane is a kind of VOC. VOCs and HAPs are categorized as gases and compounds that are harmful to the atmosphere. The leakage of oxygen or nitrogen from piping and valves is not considered a fugitive emission, since oxygen and nitrogen already exist in the atmosphere and do not cause any environment pollution.
Fugitive emission typically occurs in different industries such as oil and gas, chemical, automotive, etc., as per Figure 1.1. The concentration of this book is on fugitive emission from oil, gas, and chemical plants, such as refineries and petrochemical plants, which are responsible for almost half of total fugitive emission. In addition to fugitive emission associated with vapors and gases, any other type of emission, such as liquid hydrocarbon (oil), hydraulic oil, etc., that is harmful to the environment is addressed in this book.
Figure 1.1 Fugitive emission percentage from different industry sectors.
Figure 1.2 illustrates an oil and gas refinery, including piping, structures, and facilities—and fugitive emission. All of the piping and connections, such as flanges, could be points of leakage and emission to the environment. A flange is a ring-shaped, bulk piping component that is used to join two pieces of pipe together or connect piping to equipment in general. Flanges are typically welded to the connected pipe, but may also be threaded. Two flanges are connected with bolting (bolts and nuts), and a gasket is placed between them for sealing. Chapters 4 and 5 provide comprehensive information about flange joints, and present calculations for leakage analysis and prevention.
Figure 1.2 Fugitive emission from a refinery. (Courtesy: Shutterstock).
The EPA is an independent, executive agency of the US federal government involved in environmental protection issues. The main aims of the EPA are to protect human and environment health, improve the quality of the air and water, prevent pollution, promote energy usage efficiency, etc. In 1995, the EPA performed research to evaluate the contribution of each component or facility in oil and gas refineries to fugitive emission. The result of this research is provided in the chart illustrated in Figure 1.3. Industrial valves make up 60% of fugitive emission to the environment; thus, they are known as the most critical components when it comes to fugitive emission in the oil and gas industry. Fugitive emission from valves is discussed and reviewed by the author in a separate book named Prevention of Valve Fugitive Emissions in Oil and Gas Industry. Flanges as an important piping connection are responsible for 5.3% of the fugitive emission into the environment. Yet leakage from piping is not limited to flange connections; internal fluid can be leaked from each piping component such as the pipe itself, and fittings and pipe joints such as threads and welds. Pipe fittings are defined as piping components that are used to change the size, direction, or routing of the piping, to make a branch from the piping or to blind the end of a pipe. The main aim of this book is to provide solutions in connection to the design and selection, manufacturing, fabrication, installation, inspection, and testing of piping components and their connections to prevent leakage and fugitive emission.
Figure 1.3 Fugitive emission from different components in oil and gas refineries.
The important fact about connectors, such as flanges, that are used for piping connections is that the average number of flange connectors is higher than that of other sources of emission such as pumps, valves, drains or open-end lines, compressors, and pressure relief valves. Table 1.1 compares the range and average quantities of fugitive-emission–producing components and equipment in a typical refinery or petrochemical plant.
Table 1.1 Equipment and component quantities in a typical refinery or chemical plant as per EPA.
Component
Range
Average
Pumps
10–360
100
Valves
150–46,000
7,400
Connectors
600–60,000
12,000
Open-ended lines
1–1,600
560
Sampling connections
20–200
80
Pressure relief valves
5–360
90
The negative impact and consequences of fugitive emission are significant, and include environmental pollution and damage and loss of production, and fines are levied on companies that produce a high amount of fugitive emission. In 2003, Chevron had to pay 3.5 million USD for fugitive emissions from its refineries. It is important to bear in mind that regulatory agencies are growing less and less tolerant of fugitive emissions. The greenhouse effect and global warming are well known as negative impacts of fugitive emission on the environment. Global warming is the gradual heating of the earth’s surface, oceans, and atmosphere caused by air pollutants such as methane and carbon dioxide and the greenhouse effect. The greenhouse effect is a natural process that warms the earth’s surface. When the sun’s energy reaches the earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases. Global warming has many negative impacts on the environment, such as melting the glaciers, increasing the incidence of draught, fire, hurricanes and rain storms, causing the rise of seawater, etc. These consequences are illustrated in Figure 1.4.
Figure 1.4 Effects of global warming. (Courtesy: Shutterstock).
In summary, fugitive emission is a hazardous phenomenon that leads to atmospheric pollution and economic loss for oil and gas plants. End users, engineers, and managers of oil and gas plants have many reasons to implement fugitive emission reduction; these include ensuring the safety of the people who work in the plants and those who live nearby; avoiding fines by complying with the rules and regulations, including those that are strict about air pollution; optimizing the plant’s energy production and maximizing the plant’s safety and reliability.
1.2 Introduction to Piping Engineering
Piping engineering is a specialized discipline of mechanical engineering that involves the design and analysis of piping and the layout of piping and equipment in refineries, petrochemical plants, and other production units in the oil and gas industry. Piping or a piping system is defined as an assembly of piping components, such as pipes, fitting, and valves, used to transport and distribute process fluid between different locations. A pipe is a hollow cylinder usually with a circular cross-section used to convey substances that can flow, such as liquids, gases, powders, and solids. In fact, pipes and piping systems are like veins and arteries in oil and gas plants that transport the fluid. Piping is exposed to a combination of the pressure, temperature, load, and flow of the fluid. Additionally, piping systems are subject to corrosion and erosion, mainly due to internal erosive and corrosive fluid service, and external corrosion in the offshore environment. Some fluid services are toxic, like those that contain a considerable amount of hydrogen sulfide . Leakage of hydrogen sulfide, even in relatively low concentrations such as 100 parts per million (ppm), can kill a human. All of the above-mentioned parameters and concerns call for proper piping design and selection, fabrication and assembly, and inspection and testing to prevent leakage and ensure trouble-free operation for the long design life of a plant.
The function of piping engineering is to apply the knowledge and techniques of material and mechanical engineering, such as stress analysis, and the skills of piping layout in order to convert the process documents, such as a piping & instrument diagram (P&ID) and process flow diagram (PFD), into piping drawings and data from which the piping components can then be purchased, assembled, and tested. In short, piping engineering activities in oil and gas projects are divided into piping layout/design engineering, piping stress and analysis engineering, and piping material engineering. The main tasks involved in piping layout/design engineering are to generate a plot plan and equipment layout and a three-dimensional (3D) model of the piping and equipment. The main tasks of piping stress analysis are to define the piping stress design basis and philosophy, perform piping stress calculations, and produce an analysis report. The main tasks involved in piping material engineering are to define the piping material in cooperation with the process department, perform a corrosion study, prepare the piping specifications, define the required piping components for the purchasing department by preparing material take-off and material requisition, and produce data sheets for special piping components. Special piping components are those components that are not defined in any piping engineering standard, e.g., strainers installed before pumps or compressors to collect the particles in the fluid.
A PFD is a diagram commonly used in the oil and gas industry. It is generated by the process department to show the main process, including the main piping and equipment. A PFD shows the process of the oil, gas, and water treatment in oil field developments. PFDs in refineries and petrochemical plants illustrate how the feed fluid service that enters the plant is converted to the final product. Figure 1.5 illustrates a PFD showing the gas input to a compressor station and a knockout drum installed after the compressor to separate the liquids from the compressed gas generated in the compressor.
Figure 1.5 Pressure flow diagram (PFD) sample.
A P&ID is a diagram that show the process, including the interconnection of process equipment and the instrumentation used to control the process. P&IDs are more detailed compared to PFDs.
Piping engineering, procurement, and construction are common activities in a typical oil and gas plant. Piping engineering, including detail design, accounts for 25% of total engineering personnel hours to design the whole plant, as per Figure 1.6.
Figure 1.6 Typical engineering design personnel man-hours.
As an example, the cost of purchasing piping components, including pipe, fitting, flanges, bolts, gaskets, etc., is around 15% of the overall material cost. As shown in Figure 1.7, the cost of piping components in oil and gas projects is second only to the cost of major equipment.
Figure 1.7 Typical costs of equipment and components percentages.
The labor cost of piping construction is the highest compared to the installation of other components such as instruments, electrical components, and mechanical facilities. Refer to Figure 1.8; piping field labor cost makes up 40% of the total construction cost of the plant.
Figure 1.8 Typical field labor cost percentages.
1.3 Causes of Piping Failure and Leakage
Piping is jointed together through different approaches, such as threaded, welded, and flange connections. A flange is a component used for connecting pipes, valves, pumps, and other equipment together to form a piping system. It provides easy access for cleaning, inspection, or modification of the piping. Flanges are usually welded or screwed to the pipe. Flanged joints are made by bolting two flanges together with a gasket between them to provide a seal. A variety of factors could result in piping system failure and leakage, such as poor material selection; material corrosion; improper piping component design and selection; poor machining or corrosion of the flange face; poor gasket selection; and poor fabrication, installation, and alignment of components such as the flange during installation (see Figures 1.9 and 1.10).
Figure 1.9 Types of flange misalignment.
Figure 1.10 Flange misalignment close to a pump. (Courtesy: Shutterstock).
A study found that 80% of gasket failures in piping systems are associated with installation issues, such as gasket misalignment and lack of applied loads on the gasket from the bolting on the flange connections (see Figure 1.11). In fact, three parameters are required to maintain gasket sealing successfully: the first is resilience, such that the gasket sits on and fills the space between the flange mating surfaces and their irregularities. The second is sufficient toughness to resist loads such as blowout and extrusion. The last important factor is sufficient force from the bolting and flange joints to deform the gasket in order to provide sealing. Lack of bolt load causes insufficient flange pressure to compress the gasket and provide effective sealing, while excessive bolt and flange load can damage the flange and crush the gasket. As indicated in Figure 1.11, 69% of gasket failures are caused by lack of load and 12% are caused by gasket crushing, which can occur due to high bolt torque on the flange connection. Figure 1.12 illustrates a flange connection whose gasket failed to seal due to excessive bolt torque or force application on the right (labeled over-tight) and insufficient bolt torque implementation on the left (labeled under-tight).
Figure 1.11 Gasket failures due to insufficient bolt load and improper installation. (Courtesy: GPT).
Figure 1.12 Gasket sealing failure due to improper bolt torque application (over-tight on the right and under-tight on the left).
Figure 1.13 illustrates leakage or emission from the area between two mating flanges. The leakage illustrated in the figure could be attributed to different factors, such as corrosion of the flange or the presence of dirt and particles between the two mating flange faces. A flange face is defined as the area that holds the gasket. Additionally, lack of stress analysis and piping flexibility can result in excessive loads on the piping system, leakage from flanges, fatigue failure, damage to the piping and connected equipment, and operational problems. Figure 1.14 illustrates a disconnection of two flange joints from each other due to vibration and axial stresses.
Figure 1.13 Corrosion of flange and leakage. (Courtesy: Shutterstock).
Figure 1.14 Flange joint disconnection due to vibration and stress. (Courtesy: Shutterstock).
Corrosion is well known as the main cause of pipeline leakage in the oil and gas industry. Dents and gouges in the piping system are other reasons for piping and pipeline failures and leakage. A dent in piping and pipelines is defined as an inward, permanent, plastic deformation of the pipe wall that causes a distortion in the pipe cross-section (see Figure 1.15). A dent causes local stress and strain concentration as well as local reduction in piping diameter. A dent results in reduction of pipe strength against static and cycling loads, which could lead to bursting and leakage. Dents can be created by dropped objects, stresses and loads on the piping, poor manufacturing, accidents during shipping and installation of the piping components, etc.
Figure 1.15 Dent in piping.
Gouges are defined as defects on the pipe wall where the thickness is locally reduced. Gouges are created when metal is removed from the pipe wall through mechanical means. Figure 1.16 illustrates gouges on the piping created during installation. The sharp edges of a gouge increase the stress concentration in the piping and can threaten piping integrity. Reduction in piping wall thickness lowers the pressure containment capacity of the pipe and could put the pipe at the risk of cracking and corrosion. Figure 1.17 illustrates stress cracking in the vicinity of four gouges on a pipe.
Figure 1.16 Gouges in piping.
Figure 1.17 Stress cracking of a pipe in the vicinity of four gouges. (Courtesy: Transportation Safety Board of Canada).
Different defects on the piping system could result in pipeline failure and leakage due to busting or rupture. Bursting or rupture of a pipe due to stress or corrosion, or a combination of both, is defined as a condition in which the pipe breaks open. Figure 1.18 illustrates a burst piping elbow in a refinery that failed due to erosion corrosion. Further investigations revealed that the leakage occurred from an elbow used to change the direction of the piping. The thickness of the elbow had been reduced from 7 or 8 mm to 0.3 mm due to erosion corrosion. Rupture of a pipe is a very severe type of pipe failure that results in significant emission and leakage to the environment. The hazards for the environment and for the people who are working onsite resulting from a burst or ruptured pipe are much greater than from piping leakage.
Figure 1.18 Burst elbow in a piping system in a refinery. (Courtesy: Shutterstock).
In conclusion, causes of piping leakage and emission are related to different aspects of material selection and corrosion analysis, piping component design and selection, manufacturing, transportation, fabrication, installation, and operation. Figure 1.19 shows the different factors that can cause piping failure, leakage, and emission. These can be summarized as poor piping component design; poor material selection and corrosion study; poor piping component selection; manufacturing issues; transportation, fabrication, and installation problems; and failures during operation. Piping failures due to loads and vibration are mainly categorized as problems during operation.
Figure 1.19 Causes of piping failure and emission (leakage).
International and national codes and standards, American Society of Mechanical Engineers (ASME) and Norwegian petroleum standards (NORSOK), as well as piping handbooks and existing piping literature are used in this book to address the points that cause leakage from piping and piping components (excluding industrial valves) and to propose solutions to prevent leakage from piping systems.
Referring to the causes of piping failure and leakage illustrated in Figure 1.19, each chapter of this book is dedicated to solutions for preventing piping failure due to each cause. Chapter 2 focuses on design aspects of piping and piping components, such as wall thickness calculation and selection, as well as flange and fitting pressure class or rating determination. Chapter 3 addresses piping stress analysis due to different loads; such analysis is performed to mitigate piping failure due to loads during operation. Chapters 4 and 5 are dedicated to piping flange components, including gaskets and bolting; flange joint integrity; and leakage analysis. In addition, the application and usage of mechanical joints and compact flanges are discussed in Chapter 4. Mechanical joints and compact flanges, like standard flanges, are used to connect piping together with the possibility of dismantling the piping for maintenance or repair. But mechanical joints and compact flanges are more compact and lighter than standard flanges and have other additional benefits. Some calculations related to flanges, such as bolt length and loads and flange leakage analysis, are included in Chapter 5. Chapter 6 addresses piping material selection and corrosion prevention in different sectors of the oil and gas industry, such as offshore, refineries, petrochemical plants, etc. Poor piping component selection is another reason for piping failure. Thus, some tips for the selection of piping components based on piping codes and standards as well as industrial practices are provided in Chapter 7. Fabrication and installation of piping components as well as inspection and testing are discussed in detail in Chapter 8.
1.4 Leak Detection and Repair (LDAR)
LDAR programs are required by many standards and regulations. The main benefit of LDAR implementation is that it reduces emission from plants significantly. The EPA estimates that leakage rate can be reduced by 63% through the successful implementation of an LDAR program. LDAR is a work practice designed to identify leaks from possible leakage points, including piping and connections, and to repair them in order to reduce emission. Best practice for LDAR includes five steps: The first step is to identify the components that are at risk of leakage. All possible leakage points, such as flanges, should be selected and an identification number allocated to each one. The next step is to select the definition of leak. The lowest level of leak, such as 500 parts per million (ppm), is recommended. The third step is to monitor the components to detect possible defects and leaks. The proposal is to use EPA method 21 and an automatic data logging approach in order to save time and improve accuracy. The fourth step is to repair the components. Tightening or adjusting the bolts on the flanges could be a repair action. Different repair techniques for piping systems, mainly pipelines, are mentioned in this section. The last step is to keep a record and a data base of the components that are repaired. All of these essential LDAR steps are summarized in the flow chart illustrated in Figure 1.20.
Figure 1.20 LDAR steps and flow chart as per EPA.
Repairs could be undertaken by modifying or replacing the leaking components with leak-free components. ASME PCC-2 is one of the standards that addresses the repair of piping and pressure vessels. Different types of piping and pipeline defects may result in the need for maintenance and repair; these include corrosion and cracks, dents, welding defects, manufacturing defects, and gouges. Different techniques for repairing corroded or damaged piping to prevent leakage are discussed briefly below.
1.4.1 Composite Repair
Composite overwrap repair is a method of piping rehabilitation. It is a popular choice of repair for piping and pipeline leakage due to corrosion, denting, cracking, and other causes listed in ASME PCC-2. The main objective of composite overwrap is to reinforce the corroded wall of the piping. The use of a nonmetallic composite repair system for piping, pipeline, and pressure vessel equipment is fully explained in Article 401, part 4 of the ASME PCC-2 standard. Figure 1.21 illustrates a corroded pipe; repairing such a pipe by wrapping it with composites is illustrated in Figure 1.22.
Figure 1.21 Corroded piping.
Figure 1.22 Composite wrapping around a pipeline as a means of repair.
The materials used in composite wrapping repair include but are not limited to glass, aramid, and carbon fiber reinforcement in a thermoset polymer such as polyester, polyurethane, phenolic, epoxy, etc. The composite strip is wrapped around the pipe by hand several times. It is important that the workers are well-trained and skillful in wrapping the composite around the pipe. The personnel should be aware of the hazards associated with wrapping composite around a degraded, pressure-containing pipe.
1.4.2 Mechanical Clamp Repair
A mechanical clamp consists of two split fitting clamps that are bolted together (see Figure 1.23). The mechanical clamps are installed on the leaked or damaged part of the piping to seal and/or reinforce the area. The surface of the pipe where the clamp is installed should be cleaned properly and be free from dirt and other contaminations. The clamp could be welded to the piping after installation. Figure 1.24 illustrates the installation of a clamp on some damaged piping and flanges. A vent and drain plugs could be placed on the repair clamp to release the leaked fluid from the pipe through the clamp during assembly and before tightening the clamp bolts on the piping.
Figure 1.23 Mechanical clamp for piping repair.
Figure 1.24 Clamp installation on piping for repair.
1.4.3 Welded Leak Box Repair
Welded leak box repair consists of placing a pipe jacket with end pieces around the damaged or leaking section and seal welding it to the pipe. Seal welding is performed on two joints to provide some tightness against leakage. Figure 1.25 illustrates a welded leak box; as its name indicates, it is welded around a pipe like a jacket.
Figure 1.25 Welded leak box welded around a pipe.
1.4.4 External Weld Overlay
The main concept of external weld overlay, as illustrated in Figure 1.26, is to deposit weld reinforcement on the surface of a pipe. Several considerations should be taken for the welding task, such as the compatibility of the welding filler with the base material, the number of welding passes and the application of a post-weld heat treatment (PWHT) or other treatment to reduce the residual stress. PWHT is a method in which the welding joint is heated to a specific temperature and held at that temperature for a certain amount of time in order to release the residual stresses accrued during the welding. It should be noted that PWHT is not always required as per piping code requirement. As an example, typically PWHT is not applied on austenitic stainless steels since this type of stainless steel can be corroded in high temperature. More information about austenitic stainless steels and the intergranular stress cracking corrosion of them at high temperature is provided in Chapter 6. As an example, if some part of a pipe has a flaw or defect that reduces the pipe wall thickness at that area, welding an external overlay plate on the defective area of the pipe can compensate for the insufficient thickness of the pipe and PWHT could be applied after welding the overlay plate to relief the residual stress of the welding.
Figure 1.26 External weld overlay.
1.4.5 Sleeve Repair
A sleeve is a hollow, cylindrical tube placed around a damaged, corroded, or degraded pipe as a means of repair and to prevent leakage from the pipe. Full encirclement steel reinforcing sleeves for piping is explained in Article 206 of ASME PCC-2. The welding of the sleeve is performed along two longitudinal seams. Figure 1.27 illustrates a sleeve welded around a damaged pipe. One longitudinal weld is shown in the figure; the other longitudinal weld is located on the other side of the figure, which is not visible. Two ends of the sleeve are fillet welded to the pipe, which is known as a Type B sleeve. A Type A sleeve is another type of pipe repair sleeve without any circumferential weld (fillet weld) to the carrier pipe. Buttweld is a type of welding in which the whole cross-section areas of the pipe are welded together. Fillet weld is a type of welding between two joints when they are perpendicular or at an angle to each other.
Figure 1.27 Type B sleeve for pipe repair.
1.5 Questions and Answers
Which sentences are correct regarding fugitive emission from piping components?
Piping joints, such as flanges, are responsible for the highest percentage of fugitive emission from refineries.
Leakage of methane from a flange connection can contribute to the greenhouse effect and global warming.
Leak detection and repair (LDAR) is a good strategy for reducing fugitive emission.
Fugitive emission does not have any financial consequences for the companies responsible.
Answer: The highest percentage of fugitive emission comes from valves. In facts, 60% of fugitive emission in refineries comes from valves, while just 5.3% of fugitive emission comes from piping joints (flanges). Thus, the highest percentage of fugitive emission is not associated with flanges and piping joints, so option A is not correct. Option B is correct, because the leakage of methane from a flange or any other component does contribute to the greenhouse effect and global warming. Option C is correct, since LDAR is a good approach and strategy for reducing fugitive emission. Option D is not correct, since fugitive emission from refineries, chemical plants, and other production units does result in fines for these companies.
Which piping problem is illustrated in
Figure 1.28
, and at what stage in the lifecycle of the piping can this problem occur?
Bolting removal from flanges during installation
Flange face damage during installation
Flange misalignment during either installation or operation
Piping ovality during manufacturing
Figure 1.28 Flange alignment process. (Courtesy: Shutterstock).
Answer: The problem is misalignment of the flange. The misalignment could happen either during installation or operation. To align the flange, the bolts and nuts should be removed from the flange before aligning the two flanges together. Thus, option C is correct. The face of the flange where the gasket sits is not visible in the figure, so option B is not correct. The misalignment of the flange could occur during operation due to the effect of loads and vibration. Piping out of roundness or ovality is not a problem in this case, so option D is not correct. Out of roundness or ovality is a piping problem that can occur during manufacturing.
What is the cause of most pipeline failures? What type of piping failure is illustrated in
Figure 1.29
?
Erosion is the main cause of pipeline failure; the figure shows a corrosion failure.
Stress and loads are the main causes of pipeline failure; the figure shows an erosion failure.
Soil and sunlight are the main causes of pipeline failure; the figure shows an erosion failure.
Corrosion is the main cause of pipeline failure; the figure shows a corrosion failure.
Figure 1.29 Piping failure. (Courtesy: Shutterstock).
Answer: The main cause of pipeline failure is corrosion; the figure illustrates a corrosion failure in the piping. Thus, option D is the correct answer.
Which sentence is correct about piping repair?
Repairing the piping components is the last step of an LDAR program.
Composite piping repair is covered by ASME PCC-2.
Working with mechanical clamps during piping repair is not hazardous.
Using piping repair sleeves requires both fillet weld and buttweld.
Answer: Option A is not correct, since repairing damaged or defective piping components is one step before the last step, which is to keep a record of the emission and the repair or maintenance. Option B is correct; composite piping repair is covered by ASME PCC-2. Option C is not correct, since working with damaged, high-pressure piping while it is covered by a mechanical clamp during the repair process is hazardous. Option D is not correct, because sleeves could be Type A or B as per the ASME PCC-2 definition. A Type B sleeve has both fillet weld and buttweld, whereas a Type A sleeve has only buttweld.
Which joint problems lead to the leakage illustrated in
Figure 1.30
?
Poor welding between flange and pipe
Improper bolt and nut connection/engagement
Lack of bolt and nut engagement
None of the above
Figure 1.30 Bolting problem on a flange joint. (Courtesy: Shutterstock).
Answer: Option A is not correct. Option B is correct, because two of the bolts and nuts on the flange have a poor connection. In fact, the bolt located at approximately 6 o’clock in the flange circle is too short, so there is a lack of thread engagement between the bolt and nut. Thus, options B and C are correct. This problem is categorized as both a design and an installation issue. Lack of bolting design and length calculation during the engineering process makes the bolt shorter than it should be; as a result, the flange connection is not as strong as it should be.
Further Readings
American Society of Mechanical Engineers (ASME) PCC-2. (2018). Repair of pressure equipment and piping. New York. NY, USA.
Cosham, A. and Hopkins, P. (2003). The effect of dents in pipelines—Guidance in the pipeline defect assessment manual. Proceedings ICPVT-10. July 7–10, Vienna, Austria.
Jones, R.P., Turner, S., and Hopkins, P. (2008). A proposal for the development of an international recommended practice in pipeline defect assessment and repair selection. International conference on the evaluation of rehabilitation of pipelines. Prague.
Sotoodeh, K. (2019). Handling the pressure drop in strainers.
Journal of Marine Systems & Ocean Technology
14: 220–26. Springer.
https://doi.org/10.1007/s40868-019-00063-2
.
UHDE. (2009). Training manual—Piping. Introduction to piping engineering. Document No. 29040-PI-UFR-001. Rev. R0.
United States Environmental Protection Agency (EPA). (2007). Leak detection and repair. A best practice guide. Washington DC. USA.
Wacker, R. (2014). Prevent gasket blowout—What’s most important? Sealing sense, pumps and systems. [online] available at:
https://www.fluidsealing.com/sealingsense/Apr14.pdf
(Accessed 28 December 2020).
2 Piping Pressure Design to Prevent Leakage and Emission Wall Thickness Calculations and Pressure Rating Selection
2.1 Introduction to Piping Design
Vast quantities of flammable and explosive gases and liquids are handled each year in the oil and gas industry. The majority of accidents and emissions are due to engineering and technical faults, and failures in piping systems are frequent. Thus, the main aim of this chapter is to provide some piping and pipeline design points to prevent failure during operation. It will address calculations for piping, pipeline, and fitting wall thickness; fittings and flange pressure class or rating selection; and flange thickness selection for cases in which the flange is welded to a pipe or fitting. Different piping codes, such as ASME B31.3 “Process piping code,” ASME B31.4, “Pipeline transportation systems for liquids and slurries,” and ASME B31.8 “Gas transmission and distribution piping systems including gas pipeline,” are used for the calculation of piping and pipeline systems as well as stress analysis. Different ASME standards, such as ASME B16.5 and ASME B16.47, are referenced for piping flange pressure rating calculations. ASME B36.10M/19M are standards for piping from which standard pipe wall thickness values can be chosen. Piping stress analysis is outside the scope of this chapter; it is reviewed in Chapter 3.
Piping and pipelines are both used to transport liquids, gasses, and slurries. But what is the difference between piping and pipelines? A pipeline is a series of straight pieces of pipe welded together over a long distance. As an example, China’s West-East gas pipeline, illustrated in Figure 2.1, is approximately 9 km long. In contrast, piping is a complex network of pipes and fittings within the defined boundaries of a refinery or petrochemical plant, as illustrated in Figure 2.2. Pipelines can be above or below ground, but piping is above ground in almost all cases.
Figure 2.1 Part of the West-East gas pipeline in China. (Courtesy: Shutterstock).
Figure 2.2 Piping system in a refinery. (Courtesy: Shutterstock).
2.2 Piping and Pipeline Wall Thickness Calculation
2.2.1 Piping Wall Thickness Calculation as per ASME B31.3
Piping and pipeline wall thickness calculation is one of the most important, basic activities of piping engineers. Piping and pipelines in the oil and gas industry handle high-pressure fluid within a specific temperature range. The intention of this section is to provide guidelines and equations for the calculation of piping and pipeline wall thickness in order to prevent piping and pipeline failure and emission due to internal pressure. Insufficient pipe thickness can result in piping failure and emission, as illustrated in Figure 2.3. It should be borne in mind that different piping and pipeline ASME B31. codes provide different methods and equations for piping and pipeline calculations. This section will review the wall thickness calculations for piping and pipeline in three codes: ASME B31.3 “Process piping,” ASME B31.4, “Liquid pipeline,” and ASME B31.8, “Gas pipeline.”
Figure 2.3 Piping failure due to insufficient pipe wall thickness calculation.
Let’s start with the ASME B31.3 process piping code, which is mainly used for the design, fabrication, erection, inspection, and testing of piping in petroleum refineries, chemical plants, offshore platforms, and natural gas processing plants. Equation 2.1, as per ASME B31.3, is used to calculate piping wall thickness in relation to internal fluid pressure.
Equation 2.1 Piping wall thickness calculation as per ASME B31.3 before adding corrosion allowance and mill tolerance
where
t: piping thickness (inch);
P: piping internal pressure (pounds per square inch; psi);
D: piping outside diameter (inch);
E: longitudinal weld joint quality factor (dimensionless);
Y: material coefficient (dimensionless);
S: allowable stress (psi).
