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Structural Design of Air and Gas Ducts for Power Stations and Industrial Boiler Applications PDF

279 Pages·2020·13.423 MB·English
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Structural Design of Air and Gas Ducts for Power Stations and Industrial Boiler Applications Second Edition Prepared by the Air and Gas Duct Structural Design Committee Published by the American Society of Civil Engineers Library of Congress Cataloging-in-Publication Data Names: American Society of Civil Engineers. Air and Gas Duct Structural Design Committee. Title: Structural design of air and gas ducts for power stations and industrial boiler applications / Air and Gas Duct Structural Design Committee of the Energy Division of the American Society of Civil Engineers. Description:Secondedition.|Reston,Virginia:ASCE,AmericanSocietyofCivilEngineers, 2020.|Includesbibliographicalreferencesandindex.|Summary:“Thisreportwillassist structural engineers in understanding the structural behavior of a duct system and in analyzing and designing its many structural components”– Provided by publisher. Identifiers:LCCN2020007322|ISBN9780784415580(paperback)|ISBN9780784483008 (adobe pdf) Subjects:LCSH:Powerplants–Equipmentandsupplies.|Steam-boilers.|Airducts–Design and construction. | Flue gases. Classification: LCC TJ164 .S87 2020 | DDC 621.31/21–dc23 LC record available at https://lccn.loc.gov/2020007322 Published by the American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia 20191-4382 www.asce.org/bookstore | ascelibrary.org Anystatementsexpressedinthesematerialsarethoseoftheindividualauthorsanddonot necessarily represent the views ofASCE, whichtakes no responsibility foranystatement made herein. No reference made in this publication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. The materials are for general information only and do not represent a standardofASCE,noraretheyintendedasareferenceinpurchasespecifications,contracts, regulations, statutes, or any other legal document. ASCE makes no representation or warrantyofanykind,whetherexpressorimplied,concerningtheaccuracy,completeness, suitability, or utility of any information, apparatus, product, or process discussed in this publication,andassumesnoliabilitytherefor.Theinformationcontainedinthesematerials shouldnotbeusedwithoutfirstsecuringcompetentadvicewithrespecttoitssuitabilityfor anygeneralorspecificapplication.Anyoneutilizingsuchinformationassumesallliability arisingfromsuchuse,includingbutnotlimitedtoinfringementofanypatentorpatents. ASCEandAmericanSocietyofCivilEngineers—RegisteredinUSPatentandTrademark Office. Photocopiesandpermissions.PermissiontophotocopyorreproducematerialfromASCE publicationscanberequestedbysendinganemailtopermissions@asce.orgorbylocatinga title in the ASCE Library (http://ascelibrary.org) and using the “Permissions” link. Errata: Errata, if any, can be found at https://doi.org/10.1061/9780784415580. Copyright © 2020 by the American Society of Civil Engineers. All Rights Reserved. ISBN 978-0-7844-1558-0 (print) ISBN 978-0-7844-8300-8 (PDF) Manufactured in the United States of America. 26 25 24 23 22 21 20 1 2 3 4 5 Acknowledgments This publication never could have been completed without the hard work and dedication of all the committee members. I thank all of them for donating their time and sharing their knowledge for the betterment of our industry. Air and Gas Duct Structural Design Committee Matthew Rosecrans, Chair Sargent & Lundy Kevin Como Burns & McDonnell Jason Fifarek Sargent & Lundy John Liu Kiewit Paul Nystedt Babcock Power Lucas Pachal Nederveld, Inc. Douglas Polack American Electric Power Dennis Richard Black & Veatch (retired) Dan Sack Becht Engineering David Six Babcock & Wilcox Eric Skibbe Kiewit Jeffrey Thompson Consulting Engineer Original Air and Gas Duct Structural Design Committee Ron Schneider* Gilbert/Commonwealth Engineers Dan Blackwood Southern Company Services Vic Bochicchio Zurn Balcke-Durr, Inc. Bob Bucelwicz Boston Edison Co. Joe Clark* ABB Combustion Engineering Systems Roy Hogan* ABB Environmental Systems Bill Jacks Tennessee Valley Authority Ron Johnson* Babcock & Wilcox Paul Kokosinski* Public Service Electric & Gas Tim Laughlin* Sargent & Lundy Tom Longlais Sargent & Lundy Jim Newell Stone & Webster Engineering Corp. Rod Simonetti* Gilbert/Commonwealth Engineers Mike Stiefermann* Central Electric Company Ken Tamms American Electric Power Walt Van Dyke* Foster Wheeler Energy Corp. Ray Warren* Warren Engineering Heim Weinstein Public Service Electric & Gas Jim Whitcraft* Bechtel Power Corp. *Individuals of the original committee providing significant and time- consuming contributions to author various sections of this publication. ix x ACKNOWLEDGMENTS Otherengineersanddesignersinthecommitteemembers’organizationsalso contributed to the development of this ASCE publication. Some significant contributors are (cid:129) Daniel Biss, David Wagner, Timothy Frymoyer, and Kenneth Bauer from Gilbert/Commonwealth Engineers; (cid:129) Kurt Wachholder and Edward Hanko from Sargent & Lundy; and (cid:129) Suzana Rufener from Babcock & Wilcox. Matthew R. Rosecrans, P.E., S.E., M.ASCE PREFACE This ASCE publication has been created by a select committee of structural and mechanicalengineerswhoareextremelyexperiencedinthestructuralanalysisand designofairandflue-gasductworkforpowerstationsandlargeindustrialboiler applications. TheneedforthisASCEpublicationwasidentifiedin1991bytheASCEFossil Power Committee under the chairmanship of Thomas Longlais to capture industry practices for the design of air and gas ducts because they were not directlycoveredbybuildingcodesorotherpublicationsatthetime.Theoriginal Air&GasDuctStructuralDesignCommitteewasformedunderRonSchneider, andthiscommitteefinalizedtheoriginalASCEpublicationin1995.Over20years later the original publication was useful, but had become dated because of new industrypractices,codechanges,andadvancementsintechnology.TheAir&Gas Duct Structural Design Committee was revived by the ASCE Energy Division in February 2016 to update the publication. A group of industry experts was assembled, and all 12 committee members were given the opportunity to review andcommentonall13chaptersofthepublication.TheresultingASCEpublica- tion was unanimously agreed to by the committee. vii Contents Preface..............................................................................................................................................vii Acknowledgments........................................................................................................................ix Chapter 1 Introduction..................................................................................1 1.1 Statement of Intent and Expected Use of This Book.............................1 1.2 Limitations and Scope of This Book................................................................2 1.3 Ductwork Systems Descriptions.........................................................................4 1.4 Glossary/Definitions...............................................................................................11 1.5 Descriptions of Major Ductwork Equipment............................................19 1.6 Ductwork Accessories...........................................................................................21 References..............................................................................................................................22 Chapter 2 Ductwork Arrangement and Behavior...................................23 2.1 Overview.....................................................................................................................23 2.2 Interfaces with Equipment.................................................................................25 2.3 Thermal Expansion.................................................................................................32 2.4 Supports......................................................................................................................41 2.5 Duct Geometries.....................................................................................................51 2.6 Internal Trusses and Struts................................................................................54 2.7 Effects of the Arrangement on Loads..........................................................58 References..............................................................................................................................62 Chapter 3 Structural Material: Selection, Application, and Properties............................................................................63 3.1 Introduction...............................................................................................................63 3.2 Availability of Materials........................................................................................63 3.3 Material Properties.................................................................................................64 3.4 Material Selection...................................................................................................75 3.5 Bolts...............................................................................................................................78 3.6 Welding Electrodes................................................................................................79 3.7 Ductwork Protection.............................................................................................80 3.8 Hanger Elements.....................................................................................................82 References..............................................................................................................................82 Chapter 4 Service Conditions and Design Loads...................................85 4.1 Service Conditions..................................................................................................85 4.2 Design Loads.............................................................................................................91 References............................................................................................................................100 iii iv CONTENTS Chapter 5 Load Combinations and Associated Design Strengths....101 5.1 Design Considerations........................................................................................101 5.2 Stress-Based versus Strength-Based Design...........................................101 5.3 Strength at Temperatures within the Creep Range...........................102 5.4 Load Definitions....................................................................................................103 5.5 Developing Load Combinations for Ductwork Design......................104 5.6 Load Combinations for Allowable-Strength Design............................107 5.7 Load Combinations for Load and Resistance Factor Design.........109 References............................................................................................................................111 Chapter 6 Ductwork Global Structural Analysis...................................113 6.1 Introduction.............................................................................................................113 6.2 Global Approach...................................................................................................114 6.3 Structural Model Considerations...................................................................120 References............................................................................................................................131 Chapter 7 Plate Design..............................................................................133 7.1 Introduction.............................................................................................................133 7.2 Rectangular Ductwork Plate Design............................................................135 7.3 Circular Ductwork Plate Design.....................................................................142 7.4 Other Considerations..........................................................................................147 References............................................................................................................................150 Chapter 8 Structural Element Design.....................................................151 8.1 General Considerations......................................................................................151 8.2 Rectangular Ducts.................................................................................................152 8.3 Circular Ducts..........................................................................................................164 8.4 Internal Trusses and Struts..............................................................................168 8.5 Duct Supports.........................................................................................................175 8.6 Lateral External Tie Elements.........................................................................178 8.7 Serviceability and Deflection Limits............................................................178 References............................................................................................................................179 Chapter 9 Structural Design of Flow Distribution Devices.................181 9.1 Function of Flow Distribution Devices......................................................181 9.2 Flow Devices for Process Equipment.........................................................182 9.3 Flow Layout and Structural Considerations............................................183 9.4 Support Considerations.....................................................................................184 9.5 Structural Analysis................................................................................................185 9.6 Structural Design...................................................................................................188 References............................................................................................................................190 CONTENTS v Chapter 10 Drawing, Fabrication, and Construction: Techniques and Considerations..........................................191 10.1 General Considerations...................................................................................191 10.2 Drawings and Specifications........................................................................198 10.3 Fabrication.............................................................................................................201 10.4 Welding...................................................................................................................203 10.5 Shop Inspection..................................................................................................205 10.6 Surface Preparation...........................................................................................206 10.7 Handling and Shipping...................................................................................207 10.8 Erection...................................................................................................................210 References............................................................................................................................211 Chapter 11 Insulation and Lagging.........................................................213 11.1 Introduction...........................................................................................................213 11.2 Purpose of Insulation and Lagging...........................................................213 11.3 Types of Insulation and Lagging...............................................................215 11.4 Effects of Insulation and Lagging on the Structural Design of Ducts..................................................................................................217 11.5 Methods of Installation and Quality of the Work.............................218 11.6 Construction Details..........................................................................................222 References............................................................................................................................225 Chapter 12 Maintenance Examination of Existing Duct Systems.....227 12.1 Factors That Influence the Need for Structural Examinations....227 12.2 Field Examination Techniques.....................................................................231 12.3 Potential Damage Areas.................................................................................237 12.4 Examination Data, Evaluation, and Disposition..................................241 References............................................................................................................................244 Chapter 13 Reinforcement of Existing Ductwork.................................245 13.1 Introduction...........................................................................................................245 13.2 Evaluation of Existing Ductwork.................................................................246 13.3 Ductwork Walkdown........................................................................................246 13.4 Ductwork Modification....................................................................................247 13.5 Reinforcement......................................................................................................249 13.6 Other Considerations........................................................................................254 References............................................................................................................................256 Index.................................................................................................................257 CHAPTER 1 Introduction 1.1 STATEMENT OF INTENT AND EXPECTED USE OF THIS BOOK This ASCE publication has been created to assist structural engineers in the structural analysis and design of air and flue-gas ducts for power stations and industrial boiler applications. It is not intended to be used to size or configure ductwork for flow and pressure drop considerations. Theinformationinthisbookwaswrittenspecificallyforstructuralengineers. TheASCEcommitteeresponsibleforcreatingthisbookstronglyrecommendsthat the structural analysis and design of ducts be performed by qualified structural engineers, and not by technicians, designers, or drafters. Thestructuralengineeriscautionedagainstreadingselectedsectionswithout firstreadingandunderstandingtheentirepublication.Muchoftheinformationin each section depends on information in other sections. The structural engineer should read all the information presented in Chapters 1 through 13 and understand how it is interrelated before proceeding with analysis and design activities. Air and gas ducts for power stations and industrial boiler applications are uniquestructures.Thestructuralanalysisanddesignoftheseductsiscurrentlynot referenced or governed by any national code or design standard, and few published data on ductwork structural analysis and design procedures are available. Ductwork structural analysis and design is complicated by the need toaccommodatelargethermalmovementsandtoassessthebehaviorofmaterials at high temperatures, sometimes in a corrosive or erosive environment. The structuralbehaviorofsteelductworkcanbedifficulttounderstandforstructural engineers inexperienced in ductwork analysis and design. Usually, ductwork is initially routedand configured considering only flow and pressure drop require- ments, but the final arrangement must also consider structural support and structural behavior. In some organizations, ductwork design responsibility is divided between the mechanical process engineering and structural engineering disciplines. Often, problems that arise can be attributed to the failure to clearly assign and accept responsibilities between the disciplines. Communication between the disciplines and establishment of clear areas of responsibility are vital to ensure successful ductwork performance. 1 2 AIRANDGASDUCTS Ductwork arrangements have become more complex, and the design pressureshaveincreasedsignificantly,becauseofprecipitators,fabricfilters,NO x removal systems (also known as selective catalytic reduction, or SCR), and scrubbers being added to the boiler exhaust system as flue-gas emission require- mentsbecamemorestringentovertheyears.Iftheexperiencedstructuralengineer is not allowed input into the ductwork arrangement, a structural system could evolvethatispronetostructuraldistress.Also,higherboileroutlettemperatures andmorecorrosivescrubberoutletgaschemistryhaveincreasedtheimportance of choosing the proper materials and the proper design strengths. There is a history in the power industry of failures and major degradation of flue-gas ductwork. There are many reasons for these failures or degradation, but many of the problems might have been avoided by better initial designs or material selection. The information in this book may be used for international projects. However, if the materials to be used are different from those referenced in this book, special attention will be required from the structural engineer. Materials referenced byotherinternationalstandardsmay beused andshouldbe carefully assessed by the structural engineer, including mechanical properties, chemical composition, and material properties at elevated temperatures. Materials equivalentatambienttemperaturemaynothaveequivalentpropertiesatelevated temperatures. Withthisbook,ASCEhopestofillavoidinthestructuralengineeringfield.It isexpectedtobeusedasaguideforstructuralengineersastheyparticipateinthe routing and configuration of a ductwork system, including the duct and its support structure. This book is also expected to be a valuable tool for structural engineers in understanding the structural behavior of a duct system and in analyzing and designing its many structural components. 1.2 LIMITATIONS AND SCOPE OF THIS BOOK 1.2.1 Scope Thisbookpresentscurrentapproachestothestructuralanalysisanddesignofair andflue-gasductwork.Includedaresectionsonmaterialselection,behavior,and performance; design loads, loading combinations, and design strengths; thermal considerations; vibration considerations; structural arrangement and behavior; toggle duct behavior and expansion joint considerations; overall duct structural analysisanddesignmethods;anddesignconsiderationsforlocalelementsofthe structure,suchasstiffeners,internalbraces,connections,turningvanes,andother flow distribution devices. It also discusses drawing and specification content, fabrication and construction techniques and considerations, duct support methods, and special considerations in the design of duct support structures. It discusses field maintenance examinations and inspections for preventative

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