HVAC rectangular industrial duct construction standards

RECTANGULAR INDUSTRIAL DUCT ONSTRUCTION STANDARDS - Inch-Pound Version SHEET METAL AND AIR’ CONDITIONING CONTRACTORS’ NATIONAL ASSOCIATION, INC w w w smacna org RECTANGULAR INDUSTRIAL DUCT CONSTRUCTION STANDARDS I-P SECOND EDITION - AUGUST, 2004 SHEET METAL AND AIR CONDITIONING CONTRACTORS’ NATIONAL ASSOCIATION, INC 4201 Lafayette Center Drive Chantilly, VA 20151-1 209 www.smacna.org RECTANGULAR INDUSTRIAL DUCT CONSTRUCTION STANDARDS COPYRIGHT02004 All Rights Resewed by SHEET METAL AND AIR CONDITIONING CONTRACTORS’ NATIONAL ASSOCIATION, INC 4201 Lafayette Center Drive Chantilly, VA 20151-1 209 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 FOREWORD These duct construction standards are intended for use by contractors, fabricators and designers of air pollution control, pneumatic conveyance and industrial ventilation systems The 1980 edition of these standards was the first publication dealing with the selection of duct gauge and reinforcement for rectangular industrial duct systems While the first edition served industry very well for many years, technology has continued to evolve and in response to our membership’s request, SMACNA’s Rectangular Industrial Duct Construction Task Force led a comprehensive review and update of the fist edition, resulting in this greatly expanded and more “user friendly” version of the original publication 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 - 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 University 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 Rectangular Industrial Duct Construction Standards I-P Second Edition iii RECTANGULAR INDUSTRIAL TASK FORCE Steven P Graves, P.E., Chairman Du-Mont Company Peoria, IL Mitchell Hoppe Melrose Metal Products, Inc Fremont, CA Blake L Anderson, P.E Climate Engineers, Inc Cedar Rapids, IA Ernest R Menold, P.E Ernest D Menold, Inc Lester, PA John Gundlach McKinstry Company Seattle, WA G A Navas, Staff Liaison SMACNA, lnc Chantilly, VA CONSULTANTS Douglas S Barno DSB Marketing Group, N.A Granville, Ohio Simon J Scott Scott Consulting Services, Inc Westewille, Ohio Joseph M Plecnik, PhD, P.E Cal State University, L.B Long Beach, CA Dr Michael C Soteriades Catholic University Washington, DC FORMER COMMITTEE MEMBERS AND OTHER CONTRIBUTORS Harry Basore Kansas City, MO Donald Partney Granite City, IL Wallace E Fizer Lexington, KY Michael G Poja Milwaukee, WI William Harbaugh Houston, TX Francis J Walter Evansville, IN Marvin Hicks Idaho Falls, Idaho Harold Weisgerber Cincinnati, Ohio iv Rectangular Industrial Duct Construction Standards I-P Second Edition NOTICE TO USERS OF THIS PUBLICATION DISCLAIMER OF WARRANTIES a) The Sheet Metal and Air ConditioningContractors’National Association (“SMACNA”) provides its product for informational purposes b) The product contains “Data” which is believed by SMACNA to be accurate and correct but the data, including all information, ideas and expressionstherein, is provided strictly “AS IS”, with all faults SMACNA makes no warranty either express or implied regarding the Data and SMACNA EXPRESSLY DISCLAIMS ANY IMPLED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR PARTICULAR PURPOSE c) By using the data contained in the product user acceptsthe Data “AS IS’ and assumes all risk of loss, harm or injury that may result from its use User acknowledgesthat the Data is complex,subjectto faults and requires verification by competent professionals, and that modificationof 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, SPECIALOR CONSEQUENTIAL DAMAGES ARISING, DIRECTLY OR mDIRECTLY, OUT OF OR RELATED TO USER’S USE OF SMACNA’S PRODUCT OR MODIFICATIONOF DATA THEREIN.This limitationof liability applies even if SMACNAhas been advised of the possibility of such damages IN NO EVENT SHALL SMACNA’S LLABILITYEXCEED 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’sproduct acknowledges and accepts the foregoinglimitation 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 ACCEPTANCE This document or publication is prepared for voluntary acceptance and use within the limitations of applicationdefined herein, and otherwise as those adopting it or applying it deem appropriate.It is not a safety standard.Its applicationfor a specificproject is contingent on a designeror other authoritydefuing a specificuse SMACNAhas no power or authority to police or enforce compliance with the contentsof this document or publication and it has no role in any representationsby other parties that specific components are, in fact, in compliancewith it AMENDMENTS The Association may, from time to time, issue formal interpretationsor interim amendments, which can be of significance between successive editions PROPRIETARY PRODUCTS SMACNA encouragestechnologicaldevelopment in the interest of improving the industryfor the public benefit SMACNAdoes not, however, endorse individual manufacturersor products FORMAL INTERPRETATION 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, addressedto the Technical ResourcesDepartment and sent to the Association’snational office in Chantilly,Vuginia In the event that the petitioner has a substantivedisagreement with the interpretation, an appeal may be filed with the Technical Resources Committee, which has technical oversightresponsibility The request must pertain to a specificallyidentified portion of the document that does not involve published text which provides the requestedinformation 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 unofficial 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, consequentialor compensatory, direct or indirectly resulting from the publication, use of, or relianceupon this document SMACNA makes no guaranty or warranty as to the accuracy or completenessof any informationpublished herein APPLICATION a) Any standards contained in this publication were developedusing reliable engineeringprinciples and research plus consultation with, and information obtained from, manufacturers,users, testing laboratories, and others having specializedexperience.They are Rectangular Industrial Duct Construction Standards I-P Second Edition V subject to revision as further experience and investigationmay show is necessary or desirable Construction and products which comply with these Standards will not necessarily be acceptableif, 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 standardscontained 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 REPRINT PERMISSION Non-exclusive, royalty-free permission is granted to government and private sector specifying authorities to reproduce only any construction details found herein in their specifications and contract drawings prepared for receipt of bids on new constniction and renovation work within the United States and its territories, provided that the material copied is unaltered in substance and that the reproducer assumes all liability for the specific application, including errors in reproduction THE SMACNA LOGO The SMACNA logo is registered as a membership identification mark The Associationprescribes 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 Manufacturers Standardization Society of the Valve and Fittings Industry, Inc 127 Park Street, N.E Vienna, VA 22 180-4602 Phone: 703-281-6613 Fax: 703-281-6671 SP-58-2002, Pipe Hungers und Supports Materials, Design und Manufacture Manufacturers Standardization Society of the Valve and Fittings Industry, Inc., Vienna, VA 2002 SP-69-2002, Pipe Hungers and Supports Selection and Application ibid., 2002 D.4 D.7 OTHERRESOURCES Khan, M Z., and Walker, A C “Buckling of Plates Subjected to Localized Edge Loading” The Structural Engineer, Vol 50, NO 6, pp 225-23 June, 1972 Timoshenko, S and Woinowsky-Krieger, S., Theory of Plates and Shells, McGraw-Hill Book Company, New York, NY, 2nd Edition, 1959 Corrosion Resistant Materials Handbook, Noyes Data Corporation, Park Ridge, NJ, 1985 Handbook of Corrosion Datu, Second Edition, ASM International,Materials Park, OH, 1995 Rectangular Industrial Duct Construction Standards I-P Second Edition GLOSSARY GLOSSARY -AAbrasive - Material that, when conveyed, tends to cause surface erosion of base metal, particularly at turns or points of converging air streams Abrasion allowance - Added metal thickness beyond the structural requirements of the duct wall to compensate for future metal loss due to the abrasive action of the particulate flowing in the duct system This allowance varies from 0.006 to 0.024 in depending on the industrial duct class assigned to the application NOTE: The allowances listed in this manual are a recommendation of the Tmk Forcefor typical applications within the individual industrial duct classes However, the designer should review those values in light of individual plant experience and life cycle costing to establish an economical basisfor a specifcproject Aerosol - A suspension of ultramicroscopic particles in air or gas Allowable stress - The maximum design force per unit of area to which a member may be subjected in service ANSI - American National Standards Institute Arc welding - A welding process that fuses a material by heating it with an electric arc Arrow side - A weld symbol indicating the surface to be welded (See Figure 10-2 for a listing and description of AWS welding symbols.) ASTM - American Society for Testing Materials AWS - American Welding Society -BBend - A change in direction of a metal surface or duct system Bending moment - Sum of the moments of external forces acting on either side of a cross-section of a structural member Blast gate - A sliding plate installed in a supply or exhaust duct at right angles to the duct for the purpose of regulating air flow BOD - Symbol used in drawings to indicate bottom of duct Bolt gage - The centerline distance of a bolt circle from the heel of an angle or other structural member fabricated into the the shape of a flange Bracing (Stiffener) - A structural reinforcement member attached to a duct wall to provide additional strength and rigidity Brazing - Brazing joins materiais by heating them in the presence of a filler metal having a liquidus above 840°F but below the solidus of the base metals Heating may be provided by a variety of processes The filler distributes itself between the closely fitted surfaces of the joint by capillary action Brazing differs from soldering in that soldering filler metals have a liquidus below 840°F Butt joint - A joint between two members lying in the same piane -CCapture velocity - Minimum hood-induced air velocity necessary to capture and convey contaminant into a hood The velocity is a result of hood air flow rate and hood configuration Centerline radius (CLR) - The turning radius of an elbow measured from the radius point to the center of the duct Centrifugal fan - A device for moving gas or air The gas or air enters the inlet or eye, passes through the rotor (changing direction 90°), and is directed by a scroll-type housing to the fan outlet Centroidal moment of inertia - Moment of inertia referenced to the center of gravity of the shape in question in beam flexure it relates an entire cross-sectional area to its neutra1 axis Its symbol is I Its units are wu- ally in? Cladding - Archaic terminology whose current synonym is lagging A protective covering applied to the surface of insulation to prevent erosion and shed moisture Coefficienf of expansion - The change in length per unit length-r the change in volume per unit volume-per degree change in temperature Coliar - As it relates to industrial duct, a collar is a straight segment of material attached to the ends of re- Rectangular Industrial Duct Construction Standards I-P Second Edition G.l ducers or tapers It can also be a ring of metal welded around the duct to attach additional supports or hangers Complete (Full) penetration - See Full (‘joint) penetration.” (The term “complete” reflects current AWS terminology, while the traditional term “full” is being phased out.) Concentrated loads - Generally, a gravity load (weight) or other concentrated force (from supports or hangers) acting at a specific point, not distributed over an area Concentration - The amount of particulate or dust present in the conveyed air stream Usually expressed as the weight of particulate per unit volume of air being conveyed Connection - The means of joining two fabricated duct sections together (See Joint, duct) Conveying velocity - The speed at which air must travel through a duct to transport dust and particulate Duct class - An arbitrary classification of industrial duct that relates to abrasion and the type and concentration of materials being conveyed (See Chapter 2.) Duct saddles - A duct support fabricated to the configuration of the duct Duct span - The length of a duct segment between adjacent supports Duct thickness - The decimal or gage thickness of a duct wall Dust - Small particles of matter formed from solid inorganic materials by crushing, grinding, high temperature, etc Particulate size ranges from microscopic to submicroscopic Particles thus formed are not usually called dust unless they are smaller than about 100 microns Dye Penetrant Test - A means of detecting flaws or cracks in a weld joint through the application of a special dye (Also referred to as Penetrant Testing (PT).) -ECorrosion - Metal deterioration (loss of metal) due to chemical action Critical load - Term used to describe the maximum combination of dead and live loads acting concurrently on each individual panel of a reactangular duct, and serving as the basis for selecting a panel thickness capable of absorbing that maximum load without exceeding the specified stress and deflection limits -DDead load - A load that acts on the duct permanently (See section 4.4.) Deformation - A forced change in the shape of a metal surface Density - A materials mass per unit of volume Design - A noun or verb denoting responsibilities relating to creations of persons other than a fabricator or installer, except in the case of a design-and-build contractor Edge preparation - Edge treatment of a metal surface for welding, generally falls under the class of beveling Effective throat - The distance from the root of a fillet weld to its face On a butt welded joint, it varies depending on the joint design Expansion joint - A transverse duct joint used to absorb linear growth, and rotational, or lateral movements caused by changes in duct temperature or other factors -FFastener - A mechanical means of attaching or joining two pieces together Flange - A perpendicular surface at the ends of the duct used for the purpose of joining segments together Flange may also have a duct reinforcement function, when so designed Design criteria - The principles and parameters on which the calculations are based Full (joint) penetration - The state in which the weld metal completely fills the groove and is fused to the base metal throughout its total thickness The term “complete” reflects current AWS terminology, while the traditional term “full” is being phased out Duct - Fabricated pipe, tube, or channel that conveys air between two points Fume - A term applied to the result of fine, solid particles dispersed in air or gases and formed by con- G.2 Rectangular Industrial Duct Construction Standards * I-P Second Edition densation, sublimation, or chemical reaction such as the oxidation of metals Insulation (thermal) - A blanket or covering applied to a duct surface to reduce heat transmission -G- Internal Supports - A system of structural members designed to provide the necessary stiffening or support of the indvidual panels of a rectangular duct, and installed within the interior of the duct They may act alone or in combination with other reinforcement installed external to the duct When used in combination with external reinforcement it is usually done to reduce the size of the external reinforcement on very wide panels G60 coatings - A hot-dipped coating of zinc applied to a base metal to develop a two-sided thickness equal to 0.60 ounce per square foot as defined in ASTM A653 G90 coatings - A hot-dipped coating of zinc applied to a base metal to develop a two-sided thickness equal to 0.90 ounce per square foot as defined in ASTM A653 Gage - A graduated numerical series representing the thickness of sheet metal Each number in the series having a defined range of decimal equivalents with minimum, nominal and maximum values Gasket - A preformed ring or strip of material having elastic and compressive properties that contribute to the formation of an effective seal or closure Global buckling - Term used in reference to a type of instability failure of duct side walls under shear loads, where the failure is characterized by plastic deformation bands appearing diagonally across a large area of the panel (See Localized buckling.) Gravity load - A load whose magnitude is the weight of individual or multiple components, and its direction is always vertically downward (See Dead load.) -JJoint, duct - Location and means by which duct components are held together to form a section of duct Joint, weld - The junction where two or more members are to be joined or have been joined by a welding process Joint design - The proper selection of a method to join two or more members together Joint efficiency - Ratio of joint strength to base metal strength Joint penetration - The minimum depth to which a groove or fillet weld extends from its face into ajoint, excluding reinforcement (See Full (joint) penetration and Partial (joint) penetration.) Joint root - That portion of a joint, a line, or an area where members approach closest to each other -HHanger - A device used to suspend a duct or pipe segment from an overhead structure -KKip - One thousand pounds Ksi - One kip per square inch, 1,000 psi -I- -L- Ice load - The equivalent weight of ice accumulated on the surfaces of an exterior installation The accumulation thickness is based on historical data, collected and published as regional and national maps by the United States Weather Service (See Figure B-4.) Lagging - a protective covering applied to the exterior surface of insulation to prevent erosion and shed moisture (See also cladding) Inches of water (in wg) - A unit of pressure equal to the pressure exerted by a column of liquid water, inch high A force of 5.2 pounds per square foot or 0.0361 psi Lateral bracing - bracing attached to a building or other structure, that prevents the duct or piping from moving perpendicularly or laterally to the dierection of its run Inertia, moment of - See Centroidal moment of inertia Lateral load - A force applied perpendicular to the wall of the duct (such as a wind load) Lap joint - Joint between two overlapping members Rectangular Industrial Duct Construction Standards I-P Second Edition G.3 Live load - A load that acts intermittently or periodically (See section 4.4.) Load ratio factor (a)-The ratio of top panel loading to bottom panel loading that initiates localized side wall buckling for a given panel geometry Localized buckling -Term used in reference to a type of instability failure of duct side walls under shear loads, where the failure is characterized by plastic deformation bands appearing on one or both side panels, perpendicular to, and in the immediate area over a horizontal support member (i.e trapeze support) (See Global Buckling.) Longitudinal bracing - Bracing that prevents a duct or pipe from moving in the direction of its run -MMagnetic Particle Test - A method used for detecting flaws in weld seams Magnetic Particle Testing (MT) -Weld examination procedure based on the characteristic behavior of ferromagnetic particles in the presence of magnetic field disturbances related to surface and near surface defects in the test specimen Maintenance load - External forces applied to the exterior of a duct during maintenance activity, such as the weight of a workman, tools, etc Material class - A method by which conveyed particulates are rated based on “size, flowability, and abrasiveness” to determine the class of duct construction to be used Micron - A measure of the size of dust particles equal to one thousandth of a millimeter (10” mm), or about 3.9 x inches MIG welding (metal inert gas) - A process that welds by heating with an electric arc between a continuous consumable electrode wire and the work Shielding is by gas, a gas mixture, or a mixture of a gas and flux It is also referred to as Gas metal arc weld (GMAW) Misalignment - The offset encountered when joining two metal surfaces Mist - Small droplets of materials that are ordinarily liquid at ambient temperature and pressure G.4 Modulus of elasticity - The quotient obtained by dividing the stress per square inch on a material by the elongation in one inch caused by this stress It is normally designated by the symbol E Moment - The product of force and the perpendicular distance from the point at which the moment is calculated to the line of action of the force -NNegative pressure - Internal forces, usually created by a fan’s suction or drawing of air, applied evenly to duct walls Also, static pressure within a duct or equipment that is lower than the pressure of the surrounding environment Neutral axis - In structural members subject to a bending moment, the neutral axis is an imaginary line that divides the structural member’s crossection into two parts, one in tension and the other in compression NFPA - National Fire Prevention Association Nominal thickness - A decimal thickness that represents the midrange of upper and lower tolerances for metal thickness The midpoint usually represents a gage equivalent -0OSHA - Occupational Safety and Health Administration A U S government agency established for the purpose of enforcing the Occupational Health and Safeîy Act which promotes safety in the work place -PPartial (joint) penetration - Where the depth to which the weld metal fills the groove and is fused to the base metal is less than the joints total thickness Partial joint penetration is also an arbitrary classification assigned to certain weldedjoint designs which are known to result in less than complete joint penetration Particulate - A term used as a general reference to solid material being conveyed or captured by a duct system Penetration - Depth of weld melting, measured from the original surface of the base metal Penetrant Testing (PT) - See Dye Penetrant test Pitch - The distance between centers of intermittent welds Rectangular Industrial Duct Construction Standards I-P Second Edition Poisson’s ratio - A material constant (v) expressing the ratio of lateral strain to longitudinal strain The ratio varies for different materials, usually ranging from 0.25 to 0.35 Porosity - Gas pockets or voids in metals Positive pressure - Internal forces, usually created by a fan’s discharge or blowing of air, applied evenly to the duct walls Also, static pressure within a duct or equipment that is higher than the pressure of the surrounding environment Pounds per square inch (psi) - A measure of the normal force (in pounds) exerted by a liquid or gas on every square inch of the duct wall Pressure - The normal force exerted by a liquid or gas, per unit of area, on the wall of its container Pressure, absolute - The sum of gage pressure and atmospheric pressure Pressure, atmospheric - The pressure indicated by a barometer Standard atmosphere is the pressure equivalent to 14.696psi or 29.921 inches of mercury at 32°F trating radiation through a test object as represented by the recording of an image on film or other recording media Reactions - Forces exerted by supports to offset load being supported Reduction factor (temperature) - Factor representing the reduced strength of metals when subjected to high operating temperatures Root opening - The distance between the members to be joined at the root of the weld -SSafety factor - A constant representing the ratio of the yield stress of a material to the intended design stress In other engineering publications safety factors are sometimes quoted on the basis of ultimate strength, instead of yield strength For safety factors used in the preparation of this standard see list of (R) values in Section 4.3 Sealant - A material with the necessary cohesive and adhesive properties to form a seal for the intended service Pressure, drop - Pressure loss along the airflow path of a duct, due to friction, dynamic losses, and changes in velocity pressure Seam - The joining of two metal surfaces in a longitudinal direction Pressure, static - The force per unit area acting in a direction perpendicular to the direction of flow Seismic Bracing - a combination of longitudinal and lateral bracing to prevent duct movement in the event of earthquake or seismic activity Pressure, total - In the theory of the flow of fluids, the sum of the static pressure and the velocity pressure at the point of measurement Pressure, velocity- The kinetic pressure in the direction of flow necessary to cause flow at the observed velocity Pressure class - The upper limit of positive or negative static pressure that is expected within a given duct Procedure qualification - Use of a weld procedure proven to meet a given standard -RRadiographic Test - Procedure using an X rays to detect flaws in welded seams Radiographic Testing (RT) - Weld examination procedure based on the differentials in absorption of pene- Shear - Straining action wherein applied forces produce a sliding or skewing type of deformation A shearing force acts parallel to a plane, as distinguished from tensile or compressive forces, which act normal to a plane Size of weld - Groove weld depth of bevel plus the root penetration Fillet weld-for equal leg fillet welds, the leg length of the largest isosceles triangle that can be inscribed within the fillet weld cross- section For unequal leg fillet welds, the leg lengths of the largest right triangle that can be inscribed in the weld cross-section Slide plate - A minimum friction duct support device used in lieu of rollers to accommodate thermal expansion Smoke - The airborne solid and liquid particulates and gases that evolve when a material undergoes pyrolysis or combustion Rectangular Industrial Duct Construction Standards I-P Second Edition G.5 Snow load - The accumulation or buildup of snowfall on the top of a duct surface, which adds to its bending load Historical data of snow accumulations is collected and published by the U.S Weather Bureau in regional and national maps (See Figures B-2 and B-3.) Span - Distance between duct hangers or supports Staggered welds - Weld beads applied at regular intervals on opposite sides of a reinforcement Toe of weld - The junction between the face of a weld and the base metal -UUltrasonic Testing (UT) - Weld examination procedure using high frequency sound waves (> 20,000 Hz) to differentiate material properties, inspect materials soundness, estimate defect size, and measure thickness or distance to defects -V- Stiffener - See Bracing Stiffener spacing - The intervals between reinforcements attached to a duct Stitch welds - See Weld, intermittent Superimposed (dead or live) loads - A term used to describe certain loads which can be theoretically distributed over a panel's surface (on an area basis) and summed for computational convenience V groove weld - A weld deposited in a bevel-edged butt joint Van Stone joint - Bending the duct wall over the heel of a flange to create a seal This type ofjoint is typically only used on ducts 16 gage or thinner Velocity - A vector quantity that denotes at once the time rate and the direction of linear motion Support - A device or means of holding a duct system in place Visual Testing (VT) - Weld examination procedures using the naked eye, magnifying devices, rigid and flexible boroscopes, dye penetrant systems, and cameras or other remote optical sensors -T- -W- Tack weld - A short weld made to hold parts of a weldment in proper alignment until the final welds are made Water gage (wg) - Frequently used to express pressure in inches water gage, where each unit of pressure equals the pressure exerted by a column of liquid water inch high at a temperature of 39.2"F Temperature - Measure of the relative activity of atoms, and observed as hot or cold Weight per cubic foot - A measure of the density of a given substance expressed in pounds per cubic foot Temperature, ambient - Generally, the air temperature surrounding an object Temperature, elevated - An increase in the temperature of an air stream, above ambient, resulting from the process being exhausted NOTE: The pressure exerted by an accumulated substance on a horizontal duct supface (in pounds per square foot) can be calculated by multiplying the weight per cubic foot (dens$) of the substance by the height of the accumulation (infeet) Test ports - A capped opening in a duct wall for the purpose of inserting an instrument or recording device Weight per linear foot - The given weight of common structural steel members measured per foot of length Thermal expansion - A relationship of growth or elongation in metal surfaces from an ambient (cold) position to an elevated operating temperature (hot) Weight per square foot - The given weight of one square foot of common steel sheet and plate measured by their thickness TOD - Symbol used in drawings to indicate top of duct Weld, airtight - A general welding term used to describe welding quality This terminology allows an occasional pin hole or vacuum leak This level of quality does not generally require weld testing for defects Toe of angle - The outside edges of an angle G.6 Rectangular Industrial Duct Construction Standards I-P Second Edition Weld, fillet - A weld of approximately triangular cross-section joining two surfaces at about right angles to each other in a lap tee or comer joint Weld, gas-tight - A general welding term used to describe welding quality This terminology does not allow an occasional pin hole or vacuum leak This level of quality does not generally require weld testing for defects Weld, groove - A weld made in the groove between two (butt jointed) metal surfaces (See V groove weld.) Weld, intermittent (stitch) - Short weld made between two surfaces to securely attach bracing or stiffeners Weld, length - The specified length of stitch or intermittent weld required to provide designed strength Weld, water-tight - A general welding term used to describe welding quality This terminology does not allow an occasional pin hole or vacuum leak This level of quality commonly requires dye penetrant or other types of weld testing for verification of quality Weld axis - A line through the length of a weld perpendicular to its cross-section Weld metal - The portion of a weld that has melted during welding Weld reinforcement -Weld metal on the weld face in excess of the metal necessary for the specified weld size Weld throat - The shortest distance from the root of a fillet weld to its face On a butt welded joint, the throat is equal to the thickness of the thinnest of the parts joined Welder qualification - Demonstration of a welder’s ability to produce welds that meet prescribed standards Welding, arc - A welding process that fuses material by heating it with an electric arc Wind load - The external forces applied to a duct wall by the wind blowing against it Historical data of wind speed is collected and published by the United States Weather Bureau in regional and national maps (See Figure B- 1.) Wind speed - The velocity at which wind applies external forces to a duct wall Working pressure - The normal pressure acting on a system during operation -YYield strength - The stress accompanying a specified permanent plastic strain, and which represents the practical elastic strength for materials having a gradual knee in the stress-strain curve Rectangular Industrial Duct Construction Standards I-P Second Edition G.7 TlìIS PAGE INTENTIONALLY LEFT &LANK 6.8 Rectangular Industrial Duct Construction Standards I-P Second Edition INDEX G A Abrasioq2.3 Access Doors, 11.12 Allowable Shear Stress, 4.1 Allowable Tensile Stress, 4.1 Aluminized Steel, 1.1, 3.1, 6.25-6.43, 6.110-6.120, 8.10-8.15, 8.18-8.29, 8.3 1-8.44 Aluminum, 1.1, 3.2 Bending Moment, 4.3 Bolt Stress Area, 9.12 Bolts, 4.13, 9.10-9.13 C Carbon Steel, 1.1, 3.1, 6.25-6.43, 6.44-6.67, 6.109-6.120 Caulking, 1.3 Caulks, 9.14, 9.15 Class 1,2.1 Class 2,2.2 Class 3, 2.2 Class 4, 2.2 Class 5,2.2 Coated Steels, 6.1 Commercial Grade Carbon, 6.9 Complete Penetration Welds, 10.1 Concentration, 2.2 Concrete Fasteners,, 9.2 Concrete Inserts, 9.2 Corrosion, 3.15 Critical Load, 6.5, 7.5, 8.5 Critical Load Diagrams, 6.4, 7.4, 8.4 Cross-Sectional Area, 4.2 D Dead Loads, 4.5 Design Pressure, 1.1, 4.5, 6.1, 7.1, 8.1 Design Temperature, I 1, 6.1, 7.1 Duct Class, 1.2 Duct Selection Tables, 6.1, 7.1, 8.1 E Earthquake Loads, 4.6 Expansion Joints, 11.10 Explosion Door, 11.13 F Fasteners, 1.3 Fillet Welds, 10.2 Flange Height, 4.2 Flange Thickness, 4.2 Flanged Connections, 4.13, 11.9 Flanges, 9.15 Flexible Connections, 11.11 Formula Derivations, A Full Penetration Welds, 10.2 Galvanized Steel, 1.1, 3.1, 6.25-6.43, 6.110-6.120 Gaskets, 1.3, 9.14, 9.15 Grade Markings for Steel Bolts, 9.13 Grooved Lockseam, 1.1 Guide Specification, 1.3 H Hanger Angle, 9.9 Hanger Bar, 9.9 Hanger Rod, 9.9 Hangers, 1.3, 9.2 Ice Load, B.6 Industrial Duct, 1.1 Industrial Duct Classes, 1.2 Insulation, B.7 J Joint Sealants, 1.3, 9.14, 9.15 Knee Brace Hanger, 9.10 Knee Brace Support, 9.11 Lagging, B.8 Limits and Tolerances, 4.7 Live Loads, 4.5 Longitudinal Seam, 11.1 Lower Attachment, 9.2 Maintenance Loads, 4.6 Material (Particulate), 9.13 Material Properties, 3.14 Minimum Conveying Velocities, 2.3 Misalignment, 4.7 Modulus of Elasticity, 4.3 Modulus of Elasticity Reduction, 3.7 Moment of Inertia, 4.3 P Partial Penetration Joint, 10.2 Particulate Load, 4.6 Physical Properties, 3.4, 9.14 Pittsburgh Lock, 1.1 Plastic Materials, 3.3 Pressure Capacity, 6.1, 7.1, 8.1 Rectangular Industrial Duct, 1.1 Rectangular Industrial Duct Construction Standards I-P Second Edition 1.1 Riser Supports, 9.2 S Safety Factor, 4.1 Seismic Restraint, 12.1 Shear Capacity, 4.16 Sidewall Buckling, 4.15 Snow Load (Ground), B.4, B.5 Stainless Steel, 1.1, 3.2, 7.10-7.15, 7.18-7.29, 7.3 1-7.44 Standing Seam, 1.1, 11.1 Steel Pipe, 9.8 Stiffener Size, 4.11 Stiffeners (Reinforcements), 1.1 Structural Steel Fasteners, 9.2 Support Capacity, 9.6 Support Spacing, 4.12 support span, 4.3 supports, 1.3 Surface Preparation, C.2 Surface Preparation Techniques, 1.3 System Pressure, 4.2 1.2 T Temperature Limits, 3.14, 9.15 Thermal Expansion, 4.2, B.9 Transverse Seams, 11.1 Trapeze Hanger, 9.5 Types of Joints, 10.8 U Upper Attachment, 9.2 W Welded Joint, 1O Welded Seam, 1.1 Welding Procedures, 10.8, 10.16, 10.17 Welding Symbols, 10.16, 10.17, 10.18, 10.19, 10.20 Wind Loads, 4.6 Y Yield Strength, 4.3 Yield Strength Reduction Factor, 3.7 Rectangular Industrial Duct Construction Standards I-P Second Edition SHEET METAL AND AIR CONDITIONING CONTRACTORS’ NAT1O NA L ASSO C I A i l O N, I NC ... DOCUMENTS GLOSSARY INDEX Rectangular Industrial Duct Construction Standards I-P Second Edition 1.3 THIS PAGE INTENTIONALLY LEFT BLANK 1.4 Rectangular Industrial Duct Construction Standards i-P Second... Rectangular Industrial Duct Construction Standards I-P Second Edition j: r Ir r rO )o0 I r m 'I > P ? I F C U c U c o E c c1 s C I c d E I ; I U E g Rectangular Industrial Duct Construction Standards. .. industrial practices for contractors, design engineers, 1.4 INDUSTRIAL DUCT DESIGN The approach, or avenue to rectangular industrial duct design is as described here: Rectangular Industrial Duct