HVAC rectangular industrial duct construction standards

New Chapter of practical examples with step-by-step instructions New Duct Class 5 - for systems handling corrosives Expanded data for the selection of duct supports, fasteners, gaskets a

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RECTANGULAR

ONSTRUCTION STANDARDS

SHEET METAL AND AIR’ CONDITIONING CONTRACTORS’

NATIONAL ASSOCIATION, INC

w w w s macna o rg

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RECTANGULAR INDUSTRIAL DUCT CONSTRUCTION STANDARDS

I-P SECOND EDITION - AUGUST, 2004

SHEET METAL AND AIR CONDITIONING CONTRACTORS’

4201 Lafayette Center Drive Chantilly, VA 20151 -1 209 www.smacna.org

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RECTANGULAR INDUSTRIAL DUCT CONSTRUCTION STANDARDS

COPY RIGHT02004

All Rights Resewed

by

SHEET METAL AND AIR CONDITIONING CONTRACTORS’

4201 Lafayette Center Drive

Chantilly, VA 201 51 -1 209

Printed in the U.S.A

FIRST EDITION - 1980 I-P SECOND EDITION - AUGUST, 2004

Except as allowed in the Notice to Users and in certain licensing contracts, no part of this book may be reproduced, stored in a retrievable system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher

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While the new text includes many of the same assumptions as the original work, a number of new features have been added:

Six different types of carbon galvanized and aluminized steels

Seven different types of stainless steel alloys

Three different types of aluminum alloys

Consideration of wind, snow, ice, and other loads

Design check for localized and global modes of side panel buckling

Design capability for high temperature systems up to 800 “F, and higher with design review by a specialized professional

New Chapter of practical examples with step-by-step instructions

New Duct Class 5 - for systems handling corrosives

Expanded data for the selection of duct supports, fasteners, gaskets and joint sealants

Accepted Industry Practice for Rectangular Industrial Ducts

New Chapter on Welding

New Guide Specification for the fabrication and Installation of industrial duct systems

The Rectangular Industrial Duct Construction Task Force is deeply indebted to Doctor Michael C Soteriades who did the original work for the first edition and contributed greatly to the improvements and expansion of the technical scope

in the new edition Likewise, the task force is deeply indebted to Joseph M Plecnik, PhD, P.E of California State Uni- versity at Long Beach, who is responsible for the physical testing, finite element analysis (FEA) studies, and design guidance related to the issue of Non-Linear Elastic Buckling of Duct Side Panels on Rectangular Industrial Duct

SHEET METAL AND AIR CONDITIONING CONTRACTORS’

NATIONAL ASSOCIATION, INC

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RECTANGULAR INDUSTRIAL TASK FORCE

Steven P Graves, P.E., Chairman

Du-Mont Company

Peoria, IL

Blake L Anderson, P.E

Climate Engineers, Inc

Joseph M Plecnik, PhD, P.E

Cal State University, L.B

Fremont, CA

Ernest R Menold, P.E

Ernest D Menold, Inc

Westewille, Ohio

Dr Michael C Soteriades Catholic University Washington, DC

FORMER COMMITTEE MEMBERS AND

OTHER CONTRIBUTORS

Donald Partney Granite City, IL

Michael G Poja Milwaukee, WI

Francis J Walter Evansville, IN

Harold Weisgerber Cincinnati, Ohio

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FITNESS FOR PARTICULAR PURPOSE

c) By using the data contained in the product user accepts the Data “AS IS’ and assumes all risk of loss, harm or injury that may result from its use User acknowledges that the Data is complex, subject to faults and requires verification by competent professionals, and that modification of parts of the Data by user may impact the results or other parts of the Data

d) IN NO EVENT SHALL SMACNA BE LIABLE TO USER, OR ANY OTHER PERSON, FOR ANY INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES ARISING, DIRECTLY OR mDIRECTLY, OUT OF OR RELATED TO USER’S USE OF

SMACNA’S PRODUCT OR MODIFICATION OF DATA THEREIN This limitation of liability applies even if SMACNA has been advised of the possibility of such damages IN NO EVENT SHALL SMACNA’S LLABILITY EXCEED THE AMOUNT PAID BY

USER FOR ACCESS TO SMACNA’S PRODUCT OR $~,ooO.OO, WHICHEVER IS GREATER, REGARDLESS OF LEGAL THEORY

e) User by its use of SMACNA’s product acknowledges and accepts the foregoing limitation of liability and disclaimer of warranty and agrees to indemnify and hold harmless SMACNA from and against all injuries, claims, loss or damage arising, directly or indirectly, out of user’s access to or use of SMACNA’s product or the Data contained therein

This document or publication is prepared for voluntary acceptance and use within the limitations of application defined herein, and otherwise as those adopting it or applying it deem appropriate It is not a safety standard Its application for a specific project is contin- gent on a designer or other authority defuing a specific use SMACNA has no power or authority to police or enforce compliance with the contents of this document or publication and it has no role in any representations by other parties that specific components are, in fact, in compliance with it

a) A formal interpretation of the literal text herein or the intent of the technical committee or task force associated with the document

or publication is obtainable only on the basis of written petition, addressed to the Technical Resources Department and sent to the Association’s national office in Chantilly, Vuginia In the event that the petitioner has a substantive disagreement with the interpretation, an appeal may be filed with the Technical Resources Committee, which has technical oversight responsibility The request must pertain to a specifically identified portion of the document that does not involve published text which provides the requested information In considering such requests, the Association will not review or judge products or components as being in compliance with the document or publication Oral and written interpretations otherwise obtained from anyone affiliated with the Association are unoffi-

cial This procedure does not prevent any committee or task force chairman, member of the committee or task force, or staff liaison

from expressing an opinion on a provision within the document, provided that such person clearly states that the opinion is personal and does not represent an official act of the Association in any way, and it should not be relied on as such The Board of Directors of SMACNA shall have final authority for interpretation of this standard with such rules or procedures as they may adopt for processing same

b) SMACNA disclaims any liability for any personal injury, property damage, or other damage of any nature whatsoever, whether special, indirect, consequential or compensatory, direct or indirectly resulting from the publication, use of, or reliance upon this document SMACNA makes no guaranty or warranty as to the accuracy or completeness of any information published herein

a) Any standards contained in this publication were developed using reliable engineering principles and research plus consultation with, and information obtained from, manufacturers, users, testing laboratories, and others having specialized experience They are

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subject to revision as further experience and investigation may show is necessary or desirable Construction and products which com- ply with these Standards will not necessarily be acceptable if, when examined and tested, they are found to have other features which impair the result contemplated by these requirements The Sheet Metal and Air Conditioning Contractors’ National Association and other contributors assume no responsibility and accept no liability for the application of the principles or techniques contained in this

publication Authorities considering adoption of any standards contained herein should review all federal, state, local, and contract regulations applicable to specific installations

b) In issuing and making this document available, SMACNA is not undertaking to render professional or other services for or on behalf of any person or entity SMACNA is a t undertaking to perform any duty owed to any person or entity to someone else Any person or organization using this document should rely on his, her or its own judgement or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstance

The SMACNA logo is registered as a membership identification mark The Association prescribes acceptable use of the logo and expressly forbids the use of it to represent anything other than possession of membership Possession of membership and use of the logo in no way constitutes or reflects SMACNA approval of any product, method, or component Furthermore, compliance of any such item with standards published or recognized by SMACNA is not indicated by presence of the logo

vi

Rectangular Industrial Duct Construction Standards I-P Second Edition

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TABLE OF CONTENTS

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TABLE OF CONTENTS

FOREWORD iii

RECTANGULAR INDUSTRIAL TASK FORCE iv

FORMER COMMITTEE MEMBERS AND OTHER CONTRIBUTORS iV NOTICE TO USERS OF THIS PUBLICATION V TABLE OF CONTENTS vi¡

CHAPTER 1 INTRODUCTION Page 1.1 SCOPE 1.1 1.2 PURPOSE 1.1 1.3 DEVELOPMENT OF THE SECOND EDITION 1.1 1.4 INDUSTRIAL DUCT DESIGN 1.1 1.5 HOW TO USE THIS MANUAL 1.2 1.6 MANUAL CONTENTS 1.2 CHAPTER 2 INDUSTRIAL DUCT APPLICATIONS 2.1 INTRODUCTION 2.1 2.2 DEFINITION OF INDUSTRIAL DUCT 2.1 2.3 DUCT SYSTEM CLASSIFICATION 2.1 2.4 MATERIAL (PARTICULATE) CHARACTERISTICS AND CLASSES 2.2 CHAPTER 3 DUCT MATERIALS 3.1 INTRODUCTION 3.1 3.2 MATERIAL TYPES 3.1 3.3 CARBON AND COATED STEEL DATA 3.4 3.4 STAINLESS STEEL DATA 3.9 3.5 ALUMINUM DATA 3.12 3.6 MATERIAL PROPERTIES SUMMARY 3.14 3.7 CORROSION 3.15 CHAPTER 4 DESIGN CRITERIA 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 INTRODUCTION

GENERAL PROVISIONS

NOMENCLATURE

LOADS

LIMITS AND TOLERANCES

SERVIC EA6 I LITY AND DU RAB I LITY DESIGN OF DUCT THICKNESS

DESIGN OF STIFFENER SIZE

DESIGN OF SUPPORT SPACING

BOLTING OF CONNECTIONS

CHECKING SHEAR CAPACITY OF DUCT SIDE WALLS

CRITERIA FOR THE DESIGN OF SYSTEMS WITH INTERNAL SUPPORTS

HANGERS AND SUPPORTS

THERMAL EXPANSION

4.1 4.1 4.1 4.3 4.7 4.7 4.7 4.11 4.12 4.13 4.16 4.21 4.24 4.26

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CHAPTER 5 DESIGN EXAMPLES Page

5.1 DESIGN EXAMPLES 5.1 5.2 SUBDIVIDING PANELS AND SELECTING INTERNAL SUPPORTS 5.30 EXAMPLE #5-1 5.2 EXAMPLE #5-2 5.5 EXAMPLE #5-3 5.7 EXAMPLE #5-4 5.12 EXAMPLE #5-5 5.15 EXAMPLE #5-6 5.21 EXAMPLE #5-7 5.25

6.1 INTRODUCTION 6.1 6.2 SCOPE 6.1

6.4 USE OF THE TABLES 6.1 6.5 DESIGN PROCESS 6.5 6.6 DUCT SELECTION TABLES 6.9 6.7 AUXILIARY TABLES 6.96

7.4 USE OF THE TABLES 7.1 7.5 DESIGN PROCESS 7.5

7.6 DUCT SELECTION TABLES 7.9

7.7 AUXILIARY TABLES 7.17

8.4 USE OF THE TABLES 8.1 8.5 DESIGN PROCESS 8.5 8.6 DUCT SELECTION TABLES 8.9 8.7 AUXILIARY TABLES 8.17

9.1 INTRODUCTION AND SCOPE 9.1

9.3 GENERAL GUIDELINES 9.1 9.4 METHODS FOR HANGING AND SUPPORTING DUCT 9.2

CHAPTER 1 O WELDING

10.1 INTRODUCTION 10 1

10.5 WELDING PROCEDURES 10.8 10.6 WELDING SYMBOLS 10.16

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Page CHAPTER 11 ACCEPTED INDUSTRIAL CONSTRUCTION PRACTICES

APPENDIX A COMMENTARY ON FORMULA DERIVATIONS AND UNITS

APPENDIX B SUPPLEMENTARY DESIGN DATA

B.l INTRODUCTION 6.1

APPENDIX C COMMENTARY ON SURFACE PREPARATION TECHNIQUES

C.l INTRODUCTION C.l C.2 METAL SURFACE PREPARATION C.l

APPENDIX D REFERENCED DOCUMENTS

D.2 ANSI STANDARDS D.2 D.3 NFPASTANDARDS D.2 D.4 ASME STANDARDS D.2

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TABLES Page

2-1 Duct Classes and Minimum Conveying Velocities

2-2 Material Class Descriptions

2-3 Specific Materials Classes

3-1 Hot-rolled Steel Gages

3-2 Cold-rolled Steel Gages

Galvanized and Aluminized Steel Gages

3-3 3-4 3-5 Yield Strength Reduction Factor (vf) at Elevated Temperatures for Carbon and Coated Steels

Modulus of Elasticity Reduction Factor (77, ) at Elevated Temperatures for Carbon and Coated Steels

Yield Strength Reduction Factor (qf) at Modulus of Elasticity Reduction Factor (7, ) at Yield Strength Reduction factor ( r l f ) Modulus of Elasticity Reduction Factor (ve) 3-6 Stainless Steel Gages

Elevated Temperatures for Stainless Steel

3-9 Aluminum Sheet Gages

3-1 O at Elevated Temperatures for Aluminum

3-11 at Elevated Temperatures for Aluminum

3-1 2 Material Properties and Temperature Limits

3-1 3 Corrosion Chart

4-1 Coefficients for Mode B Analysis

5-1 Design Example Variables

6.1 -XAX List of Commercial Grade 32 ksi Carbon Steel Tables 6.2-XAX List of Structural Grade 36 ksi Carbon Steel Tables 6.3-XAX List of Structural Grade 50 ksi Carbon Steel Tables

6-X List of Auxiliary Carbon Steel Tables

7-A.X List of 35 ksi Stainless Steel Tables

7-X List of Auxiliary Stainless Steel Tables

8-A.X List of 20 ksi Aluminum Tables

8-X List of Auxiliary Aluminum Tables

9-1 Support Capacity of Horizontal Channel

9-2 Support Capacity of Horizontal Angle

9-3 Standard Steel Pipe Column - Loads

9-4 Hanger Rod Capacity

9-5 Hanger Bar Capacity

9-6 Hanger Angle Capacity

9-7 9-8 9-9 Bolt Stress Area

9-10 Grade Markings for Steel Bolts

9-11 Gaskets Caulking and Joint Sealants

9-11 10-1 Allowable Stress For Stitch Welds

10-2 Welded Joint Designs - Butt Joints (6)

10-3 Welded Joint Designs - Corner and Butt Joints (C and 9)

10-4 Welded Joint Designs - Corner and Tee Joints (C and T)

10-5 Gas Metal Arc Welding of Carbon Steel

10-6 Shielded Metal Arc Welding (SMAW) of Carbon Steel

10-7 Gas Tungsten Arc Welding (GTAW) of Carbon Steel

10-8 Gas Metal Arc Welding (GMAW) of Galvanized Steel

10-9 Shielded Metal Arc Welding (SMAW) of Galvanized Steel

10-10 Gas Tungsten Arc Welding (GTAW) of Galvanized Steel

10-11 Gas Metal Arc Welding of Stainless Steel

10-12 Shielded Metal Arc Welding (SMAW) of Austenitic Stainless Steel

10-13 Gas Tungsten Arc Welding (GTAW) of Austenitic Stainless Steel

10-1 4 Gas Metal Arc Welding of Aluminum

10-1 5 Gas Tungsten Arc Welding (GTAW) of Aluminum

3-7 3-8

Knee Brace Hanger Capacity

Knee Brace Support Capacity

Gaskets Caulking and Joint Sealants (continued)

4.10 2.4 2.5 3.4 3.5 3.6 3.7 3.7 3.10 3.10 3.11 3.12 3.13 3.13 3.14 3.16 4.10 5.1 6.9 6.43 6.69 6.95

7.9

7.17 8.9 8.17 9.6 9.7 9.8 9.9 9.9 9.9 9.10 9.11 9.12 9.13 9.14 9.15 10.3 10.4 10.5 10.6 10.10 10.11 10.11 10.12 10.12 10.12 10.13 10.14 10.14 10.15 10.15

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6-1 Conversion of Wind Loads 6.3

8-2 Insulation Physical Data 8.7

6-3 Lagging Physical Data 6.8 8-4 Thermal Expansion Chart B.9

C-1 Surface Conditions and Recommended Treatment C.2 C-2 Surface Preparation Methods C.2

Rectangular Industrial Duct Construction Standards 0 I-P Second Edition

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FIGURES Page

4-1 Critical Load Diagrams for Worst Case Conditions

4-2 Particulate Load

4-3 Panel Loading-Mode A

4-4 Panel Loading-Mode B

4-5 Stiffener Loading

4-6 Equivalent Beam Cross-Section

4-7 Flanged Connection

4-8 Types of Sidewall Buckling

4-9 Reinforcement Patch

4-10 Comparison of Critical Buckling Loads for 48 x 24 in duct

4-11 Comparison of Critical Buckling Loads for 72 x 36 in duct

4-12 Internal Supports

4-13 Fixed Stiffeners

4-1 4 Unfixed Stiff eners

4-1 5 Definition of Riser Support Loads

5-1 Subdividing Panels

5-2 Internal Pipe Supports

6-2 Stiffening Guidelines for Flat Panels

6-3 Sample Panel capacity Options from Table 6.1 -1 A l

6-4 Panel Thickness ¿? Deflection per Stiffener Spacing

6-5 Stiffener Size per Stiffener Spacing

7-3 Sample Panel capacity Options from Table 7-A.3

7-4 Panel Thickness & Deflection per Stiffener Spacing

8-3 Sample Panel Capacity Options from Table 8-A.2

8-4 Panel Thickness & Deflection per Stiffener Spacing

9-1 Hanger Attachments to Structures

9-2 Upper Attachment Devices - Typical

10-1 Joints, Welds, and Grooves

10-2 10-3 Supplementary Symbols

10-4 Typical Weld Symbols Used for Sheet Metal and Light Plate

10-5 Plate Welding Symbols

11 -1 Longitudinal Seams

11 -2 Longitudinal Seams (continued)

11-3 Transverse Seams or Joints

11 -4 Crossbraking Light Gage Panels

11-5 Types of Stiffeners

11-6 Types of Stiffeners (continued)

11 -7 Internal Pipe Supports

11 -8 Types of Flanged Connections

11 -9 Expansion Joints

11 -1 O Flexible Connections

11-11 Access Doors

11 -1 2 Explosion Door

11-13 Various Fittings

6-1 Basic Wind Speed (mph)

B-2 Snow Ground Load - Western U.S (Ib/sq ft)

B-3 Snow Ground Load - eastern U.S (Ib/sq ft)

B-4 Glaze Ice Accretion Zone

Standard Location of Elements of a Welding Symbol

4.4 4.5 4.8 4.10 4.11 4.13 4.13 4.17 4.18 4.19 4.20 4.21 4.22 4.22 4.25 5.31 5.33 6.4 6.6 6.7 6.7 6.8 7.4 7.6 7.7 7.7

7.8

8.4 8.6 8.7 8.7 8.8 9.3 9.4 10.7 10.18 10.18 10.19 10.20 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 11.10 11.11 11.12 11.13 11.14 B.2

8.4

8.5 B.6

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CHAPTER 1

INTRODUCTION

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CHAPTER 1 INTRODUCTION

thorities

The scope of this manual includes the determination of

the necessary construction details for the fabrication

and installation of rectangular metallic industrial duct

within the following general categories, and as further

detailed in the scope of individual chapters, through a

variety of both analytical and empirical methods:

Fabricated from flat sheet or plate panels, us-

ing welded seam, grooved lockseam, Pitts-

burgh lock, and standing seam techniques

From commercial grades of carbon, galva-

nized, aluminized, or stainless steel, or alu-

minum of the various grades and types as de-

scribed in Chapter 3

For a design pressure within the range from

negative 150 in wg to positive 150 in wg

To be supported at intervals not exceeding

30 ft

For a design temperature not exceeding the

specific operating limits listed for each type

and grade of metal included in Chapter 3

With panel widths (w) up to 12 ft

Listing of rated stiffeners, flanges, hanger

and support elements, and the methods for se-

lecting them for specific structural loads

An accepted industry practices for the fab-

rication and installation of rectangular metal-

lic industrial duct, with its fittings, appurte-

nances, accessories, insulation, lagging,

hangers and supports

PURPOSE

There were three primary purposes behind the devel-

opment of this manual:

To develop minimum standards for the fab-

rication and installation of metallic rectangu-

lar industrial duct systems

To develop new, and collect existing, duct

construction practices and data to serve as an

authoritative source of accepted industrial

practices for contractors, design engineers,

To provide an authoritative source of docu- mentation and terminology for operations in- volved in the construction and installation of rectangular metallic industrial duct

EDITION

The objectives behind the development of this second

edition of SMACNA’s Rectangular Industrial Duct

first edition; update the theoretical basis for design; improve the presentation to make the expanded publication more “user friendly;” to cover both the simple, low or moderate temperature and pressure indoor systems, as well as the more complex outdoor systems, operating at moderate to high temperature and pressure, and subjected to higher and more complex exter- nal loading

To achieve these objectives the following steps were taken:

al and localized shear capacity of the side walls

Laboratory testing and data analysis on rectangular duct were completed to support the addition of a side wall shear capacity check

to those already introduced in the first edition

Material previously covered in broad terms was expanded through in-depth coverage New chapters were added covering such duct fabrication topics as Stiffeners, Flanges, and Fasteners; Hangers and Supports; Welding; Accepted Industrial Construction Practices; and a Guide Specification

To provide for the design process of duct systems from the very simple to the complex, while making the process %er friendly,” the design or duct selection process was developed as a Table Driven Process

INDUSTRIAL DUCT DESIGN

The approach, or avenue to rectangular industrial duct design is as described here:

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Table Driven Process - The selection data for rectan-

gular duct is divided into three chapters, each dealing

with a different material type: Carbon, Galvanized,

and Aluminized Steel (Chapter 6), Stainless Steel

(Chapter 7), and Aluminum (Chapter 8) Each chapter

has its own detailed example covering the main selec-

tion options Use of this design process is not limited

to indoor applications, but includes wind loads and

snowhce or maintenance loads, in addition to internal

particulate loads

As described in the above, it has been an objective of

the Rectangular Industrial Duct Construction Task

Force to make this publication more “user friendly”

than its predecessor

The following tips are intended to familiarize the user

with the content and organization of this manual They

are also intended to guide the user in selecting the right

chapter or sequence of chapters to consult depending

on the immediate objective

a Chapters 2 and 3 are especially important to

the specifying engineer or to a “designibuild”

contractor Chapter 2 contains basic informa-

tion necessary for identifying and speciQing

the duct class

b Chapter 3 deals entirely with detailed infor-

mation on the mechanical characteristics of

all the metals covered by these construction

standards; it also includes a corrosion table

covering various metals and liner materials

and their corrosion performance when sub-

jected to various corrosive agents Chapter 3

information is useful in either selecting and

speci@ing a duct material or in identifjing

the mechanical characteristics of specified

duct materials

c Chapters 4 and 5 are of interest to all users

There is useful information, examples, and

guidance in these two chapters that may be of

greatest benefit to speci@ing engineers, de-

signers, and contractors

d Chapters 6,7, and 8 constitute the bulk of the

material needed for duct selection

e Chapter 9, 10, and 11 all deal with construc-

tion details and accepted industry practices

for rectangular duct and appurtenances

These chapters are of interest to all users

The Appendices and Glossary contain terminology, design data, and other supplementary information useful to both specifiers and contractors

MANUAL CONTENTS

The introduction outlines the format and layout of the manual, provides instruction for its use, and contains

a summary of the contents of each chapter

APPLICATIONS

This chapter contains various definitions and information related to industrial duct classes, as well as rele- vant physical characteristics of materials frequently conveyed in industrial duct systems It is envisioned that the designer will use the information contained in this chapter (or similar information from other sources such as those listed in section 2.2) to speci@ the most appropriate Duct Class for the system under consideration, and the concentration and characteristics of the

materials being conveyed The specification of the

This chapter contains detailed information on the physical characteristics of the most common materials used in industrial duct construction Also included are brief descriptions of each material type, its most common uses, and some limitations that may apply It is envisioned that this chapter may be used as a reference when selecting duct materials

This chapter contains design criteria-subject to the limitations expressed in section 4.2-for the construction of rectangular industrial duct

This chapter contains several industrial duct design cases, fully developed with references to the applicable sections, equations, tables, and figures contained

in other parts of the manual including internal pipe supports, stiffeners, support spans, flanges, and side wall buckling

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CHAPTER 6 DUCT SELECTION TABLES

CARBON,GALVANIZED, AND ALUMINIZED STEEL

This chapter contains the basic duct selection tables

for rectangular industrial ducts, fabricated using longi-

tudinal welded seam or lockseam techniques, from

carbon, galvanized, or aluminized steels as described

in Chapter 3

any of the stainless steel alloys described in Chapter 3

STAINLESS STEEL

ALUMINUM

any of the aluminum alloys described in Chapter 3

TENERS, GASKETS, CAULK- ING, AND JOINT SEALANTS

This chapter contains the necessary tables, instruc-

tions, and examples to assist the user in selecting from

among various s p e s of hangers, supports, fasteners,

gaskets, caulking, and joint sealants

CHAPTER 10 WELDING

The information contained in this chapter is designed

to identify the welding assumptions used in the struc-

tural design of SMACNA rectangular industrial ducts

Additionally, there is useful commentary on accepted

industry practice concerning welding, guidelines for

the application of partial and full (or complete) joint

penetration designs, tables describing full and partial penetration joint designs, data useful in developing welding procedures, and a description and commentary on the use of AWS welding symbols

CHAPTER 11 ACCEPTED INDUSTRIAL

CONSTRUCTION PRACTICES

This chapter contains those features of rectangular duct fabrication for which there exists a body of accepted field experience with practices having a proven record of satisfactory performance

CHAPTER 12 GUIDE SPECIFICATION

This chapter provides a guide for specifying rectangular industrial duct for industrial ventilation systems The guide specification is not intended as a reference document, but rather as a guide for the development of specifications for a particular project The guide specification must be edited to fit the conditions of use and work assignments Particular attention should be giv-

en to the deletion of inapplicable provisions and inclu- sion of necessary items related to a specific project

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D GLOSSARY INDEX

COMMENTARY ON FORMULA DERIVATION§ AND UNITS

SUPPLEMENTARY DESIGN DATA

COMMENTARY ON SURFACE PREPARATION TECHNIQUES REFERENCED DOCUMENTS

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THIS PAGE INTENTIONALLY LEFT BLANK

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CHAPTER 2

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CHAPTER 2 INDUSTRIAL DUCT APPLICATIONS

fire protection, and drainage

This chapter contains various definitions and informa-

tion related to industrial duct classes as well as rele-

vant physical characteristics of materials frequently

conveyed in industrial duct systems It is envisioned

that the designer will use the information contained in

this chapter or similar information from other sources,

such as those listed in section 2.2, to specify the most

appropriate Duct Class for the system under consider-

ation, and the concentration and characteristics of the

materials being conveyed We can not over-emphasize

the importance that the specification of the Duct Class

and an accurate appraisal of the conveying character-

istics of the materials being conveyed have on the suc-

cessful design of an industrial duct system

DUCT

Industrial duct is a broad classification of duct work

used for many diverse applications Air pollution con-

trol systems, industrial exhaust systems, general plant

process ventilation, and systems outside the pressure

range of commercial system standards are classified as

industrial systems

Independent of the operating temperature and pres-

sure, industrial duct usually conveys air or gases con-

taminated with particulate or corrosive aerosols at ve-

locities in excess of 2000 fpm OSHA defines the

exhaust ventilation system as a system for removing

contaminated air from a space The general list of in-

dustrial contaminants includes dusts, fumes, mists, va-

pors, and gases

Some industrial applications may include ducts oper-

ating at pressures within the range typical of systems

covered by SMACNA's HVAC Duct Construction

Standards, Metal and Flexible, Second Edition, 1995,

(Addendum No i, 1997) that is i 10 in wg While

there may exist an overlap in operating pressures and

temperatures, closer inspection reveals marked differ-

ences between industrial and HVAC applications in

performance, maintenance, and structural require-

ments

Industrial duct is found in industries such as: automo-

tive, foundry, mining, petrochemical, pulp and paper,

semiconductors, and other manufacturing Industrial

ducts are also used in pneumatic conveying systems

These systems often require special structural consid-

erations due to the possibiliîy of erosion, corrosion,

and particulate accumulation loading They may also

Industrial duct used in food processing and in systems handling materials such as rubber and paper requires smooth internal surfaces to prevent accumulation or contamination; this requirement often dictates the joining methods, which may therefore be limited to welding

There are currently five classes of industrial duct The designer should carefully analyze his application and specify the duct classification that most closely de- scribes the intended use, to ensure proper construction While round duct is preferred in industrial ventilation, air pollution control and dust collection systems due to its efficient air flow and superior strength characteristics, there exist many circumstances where only the compact nature of rectangular ducts wil suffice While this manual deals with construction standards for rectangular industrial duct, it is not intended to be

a source of system design information For that purpose, some of the more widely used sources are:

Conference of Governmental Industrial Hy-

gienists, Inc., Cincinnati, OH 2004

ANSIINFPA 91, Standard for Exhaust Sys-

tems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Sol- ids National Fire Protection Association,

Quincy, MA 1999

ANSUAIHA Standard 29.2, Fundamentals

Governing the Design and Operation of Lo- cal Exhaust Ventilation Systems American

National Standards Institute, New York, New York ibid 2001

ANSI/CEMA Standard 550-2003, Class$-

cations and Dejìnitions of Bulk Materials,

Conveyor Equipment Manufacturers Associ- ation, Naples, Florida 2003

DUCT SYSTEM CLASSIFICATION

There are five classifications of industrial duct systems:

Class 1: Non-abrasive, non-corrosive applica-

tions, including contaminated duct sections of make-up air and general ventilation systems, and gaseous emission control systems

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NOTE: At the option of the specifier, Class I in-

make-up air, general ventilation and distribution

systems in industrial plants and production areas

duct may more adequately meet the physical de-

mands of exposure to heavy traflc andfrequent

system modjìcations resulting j?om changes in

production processes and plant layout

Class 2: Applications with light to moderately

abrasive particulate in light concentration: buff-

ing and polishing, woodworking, grain dust, etc

Class 3: Applications with highly abrasive par-

ticulate in low concentrations or moderately abra-

sive particulate in higher concentrations; such as

abrasive cleaning operations, dryers and kilns,

boiler breaching, sand handling, etc

Class 4: Applications with highly abrasive particu-

late in high concentrations; such as: high concentra-

tions of particulate ffom any of the examples listed

under Class 3 (used in heavy industrial plants, such

as: steel mills, foundries, mining, and smelting)

Class 5: Applications with corrosives, such as

acid vapors

The first four classifications were originally adopted

by the American Conference of Governmental Indus-

trial Hygienists and published in the Industrial Ven-

received wide acceptance throughout the industrial

ventilation industry Class 5 appeared in the Uniform

Mechanical Code in 1991

Table 2-1 lists duct classes and recommended mini-

mum conveying velocities

ACTERISTICS AND CLASSES

The successful design of an industrial duct system be-

gins with an accurate appraisal of the characteristics of

the matenal to be conveyed A few important charac-

teristics merit special consideration

The abrasiveness of the material being conveyed must

be determined in order to select the most appropriate

duct class

The concentration of the material is determined by the

customer’s exhausting and conveying requirements

and also affects Duct Class selection

The corrosiveness of the material is determined from

the customer’s material specifications or material safety data sheets

Consideration should also be given to the weight per cubic foot of the material, its dustiness, wetness, stick- iness, and temperature The data given in these tables

is for average conditions and materials Each charac- teristic may vary in specific instances

Assigning classes to a material quantifies its characteristics of particle size, flowability, and abrasiveness

among others Table 2-2 is an index of material characteristics, each is represented by a letter or number Combining these letters and numbers to form a Class Identification string, renders a concise description of the material Table 2-3 lists many common materials and their Class Identification, which serve as a conve- nient cross-reference to the actual material characteristics as listed in Table 2-2

The following example illustrates how these tables may be used A designer locates Salt (common dry,

coarse) in Table 2-3 It lists a densiîy that varies between 45 and 50 lb/ft3 and its Class C37PL identifies the following characteristics: The first letter represents Particle Size; referring to Table 2-2, the letter C corresponds to a particle size described as: “Granular

-% in mesh and under.” The second position on the Class Identification string represents Flowability and

is occupied by the number 3, which in Table 2-2 is described as “Sluggish - with an angle of repose of 45”

or greater.” The next position represents Abrasiveness and is occupied by the number 7 which in Table 2-2 is

described as: “Moderately Abrasive.” The balance of the Class description consists of one or more letters identifying other characteristics such as: P indicates Moderately Corrosive, and L represents Hygroscopic, which means that salt tends to absorb moisture from the environment and becomes wet Based on this type

of information, the concentration of the particulate to

be conveyed, and the definitions of Duct Class in Table 2-1, the designer can then specify the duct class that he deems most closely representative of the design application

In the case of materials not listed in Table 2-3 the user

is directed to other design sources, such as those listed

in section 2.2, which may have more extensive materi-

al lists In the absence of more definitive information from other sources, a rough appraisal may be made by comparison with other listed materials of the same general type

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Minimum Eonveying Velocities

Zinc and aluminum oxide fumes, welding fumes, paint overspray, etc

Cotton lint, wood flour, litho pow-

Moderate

High

Fine rubber dust, Bakelite molding powder dust, jute lint, cotton dust, light shavings, leather shavings, soap dust, dry fine sawdust, grain dust, and buffing and polishing dust

Dry Dusts and

Class 3 materials in low to moderate concentrations, including granite dust, silica flour, material handling (general), brick cutting, clay dust, foundry (general), limestone dust, abrasive cleaning operations, dryers, kilns, boiler breaching, sand handling, manganese, steel chips, coke, etc

Class 2 materials in moderate to high concentrations, including sawdust (heavy and wet), grinding dust, buffing lint (dry), wool jute dust (shaker waste), coffee beans, shoe dust, etc

Lead dust with small chips, moist cement dust, wet furnace slag, wet mortar, buffing lint (sticky), quick lime dust, etc

Corrosive applications; laboratory fume hoods, plating tanks containing corrosive chemicals, etc

Table 2-1 Duct Classes and Minimum Conveying Velocities

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Lumpy-containing lumps over Yz in

Irregular-fibrous, stringy, or the like

D

H

Flowability

I Very free flowing-angle of repose up to 30" 1 1

Free flowing-angle of repose 30" to 45"

Sluggish-angle of repose 45" and up

I Packs under pressure

2

1 Contaminable, affecting use or saleability I K

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Rectangular Industrial Duct Construction Standards i-P Second Edition 2.9

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THIS PAGE INTENTIONALLY LEFT BLANK

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CHAPTER 3

DUCT MATERIALS

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CHAPTER 3 DUCT MATERIALS

This chapter contains detailed information on the

physical characteristics of the most common materials

used in industrial duct construction Also included are

brief descriptions of each material type, its most com-

mon uses, and some limitations that may apply It is en-

visioned that this chapter will be used as a reference by

contractors and duct designers following the design

procedures lì-om Chapter 4, and the examples in Chap-

ter 5 or using the design tables in Chapters 6 through

8

There is a wide range of materials available for indus-

trial duct construction Following are descriptions of

the most common materials covered by this manual

Hot-rolled (carbon) steel is the most common material

used in industrial duct construction It is often referred

to as IIRS It is understood that this refers to carbon

steel, it is also known as mild steel Many different

shapes and sizes of HRS structural members are avail-

able for duct reinforcement This material is extremely

versatile in its fabrication and uses It is easily shaped,

formed and joined, using every metal fabrication pro-

cess known to man Specifications for the various

types of hot-rolled steel include:

Hot-rolled steel sheet, ASTM A1011 in com-

mercial, structural, and high strength grades

Hot-rolled steel plate, ASTM A283 in low

and intermediate tensile strength, and ASTM

A572 in high sîrength grades

Hot-rolled structural steel shapes and plate,

ASTM A36

NOTES:

a Carbon steel is not recommended for applica-

tions where temperatures exceeding 650°F

are expected unless consideration (which is

beyond the intended scope of this document)

is given to this higher temperature in duct de-

sign

b Carbon steels are generally not recom-

mended for systems conveying corrosive

aerosols

Cold-rolled (carbon) steel is fi-equently used in the fabrication of industrial duct systems We will often refer

to it as CRS ASTM A1008 is the standard specification for cold-rolled steel sheet in commercial, structur-

al, and high strength grades This material is easily fabricated and welded Cold-rolled steel is often se- lected where good to excellent paint finishing properties are required

NOTES:

a

b

3.2.3

As noted in the previous section, the maxi-

mum recommended operating temperature for all carbon steels is 650°F

Carbon steels are generally not recommended for systems conveying corrosive aerosols

Galvanized Steel

Galvanized steel sheet is also used in the fabrication of industrial duct systems The specifications for galvanized steel sheet are ASTM A924 and A653

Galvanized steel is typically not available beyond 10 ga When necessary, carbon steel is hot-dipped galvanized prior to fabrication

Aluminized Steel

Aluminized steel is sheet carbon steel that has been hot-dip coated on both sides with an aluminum silicon alloy, thus meeting the requirements of ASTM A463lA463M It is intended principally for heat-resistant applications or where atmospheric type corrosion (mild industrial, salt spray, or marine environment) is present Since aluminized steel is currently only available in 11 gage and lighter, its use in industri-

al duct construction is, unfortunately, somewhat limit-

ed Structural considerations in duct construction require that, as the design temperature increases, the duct thickness be increased to offset the reduction in material strength Therefore, with the limited thickness availability of aluminized steel, its use becomes

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dependant on designs that can be satisfied by 11 gage

or lighter metal

Aluminized steel is most often used as an alternative

to galvanized and carbon steels due to its better high

temperature and corrosion resistance characteristics

Except for its unavailability in heavier gages, it also

appears promising for use in higher temperature

(650°F to 1050°F) industrial duct applications filling

the gap between the less expensive materials (carbon

steel and galvanized steel), that lack the durability or

the necessary properties, and the more expensive

stainless steels that may deliver better properties than

are required

Stainless steel in sheet, plate, and a limited selection

of structural shapes is often used in industrial duct sys-

tems Stainless steel alloys, highly resistive to corro-

sion and high temperatures are available for use where

extreme conditions are anticipated (See cautionary

notes below and on Table 3-12)

The following material specifications for stainless

steel alloys are frequently used in the fabrication of in-

dustrial duct systems: ASTM A480lA480M Standard

Rolled Stainless and Heat-Resisting Steel Plate, Sheet

Heat-Resisting Chromium and Chromium-Nickel

Stainless Steel Plate, Sheet and Strip

Among the many alloy types included in the ASTM

standards referenced above, the following list repre-

sents those most commonly encountered in industrial

duct construction and for which design data is offered

in this manual:

Types 304 (commonly known as 18-8 stain-

less steel) and 304-L

Types 316,316-L, 310,321, and 347

Types 410 and 430

NOTES:

a The stainless steels mentioned above are gen-

erally the most common of their type How-

ever, there are other specialty stainless steels

corresponding to each one of those listed,

which have characteristics similar to the gen-

eral type, only more so Some examples are:

Type 3 17 is similar to Type 3 16, except it has

higher chromium for increased corrosion re-

sistance; Types 416 and 440 are similar to

Type 410, except that 416 has improved ma-

Always consult steel manufacturers to obtain their recommendation or to veri9 the selection of the material best suited for challeng- ing applications Corrosive chemicals and high operating temperatures, alone or in various combinations, present an operating environment that merits approaching with caution

Because the yield strength of stainless steel declines rapidly at temperatures in excess of 800°F and because other material selection considerations are also critical at high temperatures, duct designers are cautioned about the potentially severe risks that may be encountered in designing ducts for operation at high temperature SMACNA has established graduated temperature limits for the most common stainless steels and corresponding levels of caution in approaching such high

temperature duct design, see Table 3-12

Aluminum sheet, Alloy 3003-H14, ASTM B209

Aluminum sheet, Alloy 5052-H32, ASTM B209

Aluminum plate, Alloy 6061-T6, ASTM B209

Aluminum structural shapes, Alloy 6061-T6 and T4, ASTM B209

Aluminum can be easily worked into any form and readily accepts a wide variety of surface finishes Al- most any method of joining is applicable to aluminum including welding, brazing, riveting and lock-formin-

g Aluminum is resistant to some types of corrosion;

however, the contractor is cautioned to consult the sup- plier about specific applications Aluminum ducts fabricated under this standard are only recommended for

Class 1 industrial duct applications (See section 2.3

for definition and limitations of the different industrial duct classes.)

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400 Y, or systems conveying corrosive, flammable or

explosive vapors, fumes, mists, or particulates of any

type

where their use in exhausting corrosive and toxic fumes may be a sound alternative Duct fabrication standards for these types of applications are covered in the following SMACNA publications:

First Edition, June 1997

Thermoset and Thermoplastic Materials are frequent-

ly specified for a wide range of industrial applications,

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