This standard is issued under the fixed designation A/AM; the number 1 This practice is under the jurisdiction of ASTM Committee A05 on Metallic-. In all cases only the current version of the standard as published by ASTM is to be considered the official document. Designation: A – 76 (Reapproved ) . ASTM A – A M – 02 – Download as PDF File .pdf), Text File .txt) or read online.
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In welding any intermediate lengths along one side of a common member, care should be taken to prevent warpage of the common member due to the application of high heat on the same side at various intervals along its length.
A38 published as A – 55 T.
ASTM A384 Recommendations
The following displays various methods to reduce or eliminate the potential for warpage and distortion. Inch pounds and SI units are not necessarily exact equivalents.
I the f frame has to be dipped one half at a time, it will be better to have the sheets galvanized, rolled flat after galvanizing, and assembled to the galvanized frame by the use of aluminum alloy or galvanized rivets.
Wherever possible, galvanize thick and thin portions separately and join them after galvanizing. Asymmetrical Design Symmetrical sections such as I-beams and tubing will be less likely to distort than asymmetrical pieces camber beams, channels, tees, custom beams, girders because the thermal expansion forces above and below the natural axes balance each other.
This specification deals with safeguarding against warpage and distortion during hot-dip galvanizing of steel assemblies.
Necessary precautions to fabricate properly and prepare the material for galvanizing to prevent embrittlement are described in Practice A Where welding before galvanizing cannot be avoided, the internal stresses in the connections can be minimized by avoiding joint designs or weld lengths which are greater than statically required, and by placing welds near to and symmetrically around the neutral axis – aligning welds so that shrinkage and opposing forces are balanced rather than all pulling in the same direction.
This is not true of an I-beam, pipe, H-column, or any other section that is symmetrical about both its major axes.
It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. If the angie steel frame and sheets are punched prior to galvanizing the recommended procedurethe use of drift pins to bring the holes into alignment should be avoided as far as possible at the time the sheets and frame are assembled.
Oftentimes sheet or plate can be returned to a flattened state using a jig or by weighing the product down on a flat surface during the cool-down. It is recommended that welding procedures be carried out in conformancewith the pertinent specificationsof the American Welding Society. Current edition approved Oct. In nearly every case, regardless of size, channels require straightening after galvanizing.
Welding results in significant residual stress in small areas of an assembly due to the extreme temperature differences experienced. Symmetrical sections such as I-beams and tubing will be less likely to distort than asymmetrical pieces camber beams, channels, tees, custom beams, girders because the thermal expansion forces above and below the natural axes balance each other.
ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date. Suggested Corrections for Panel Fabrication 4. Optimize Welding Before Hot-Dip Galvanizing Welding results in significant residual stress in small areas of an assembly due to the extreme temperature differences experienced. A – 76 Reapproved Standard Practice for Safeguarding Against Warpage and Distortion During Hot-Dip Galvanizing of Steel Assemblies’ This standard is issued under the fixed designation A ; the number immediately foliowing the designation indicates the year of original adoption or, in the case of revision, the year of last revision.
Specify symmetrically rolled sections instead of angle or channel frames.
Steel invariably contains internal stresses induced at the mill from rolling operations used to bring structures, aetm, and sheet to the final thickness. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters.
ASTM A Recommendations | American Galvanizer’s Association
Common distorted and warped members of assemblies are sheets or plates assembled by welding or riveting. Last previous edition A – asrm Minimize Thick and Thin Material in the Same Assembly When two steels of different thicknesses are assembled and brought up to galvanizing temperature, the thinner steel heats up and expands more quickly than the thicker steel.
Channels and other nonsymmetrical sections should be avoided for the framework of a sheet metal assembly that is to be hot-dip galvanized whenever it is possible to use symmetrical shapes or sections.
Suggested corrections adtm panel fabrication are detailed. Avoid Susceptible Thin Sheet Steels Steel invariably contains internal stresses induced at the mill from rolling operations used to bring structures, plate, and sheet to the final thickness. A number in parentheses indicates the year of last reapproval. When ashm steels of different thicknesses are assembled and brought up to galvanizing temperature, the thinner steel heats up and expands more quickly than the thicker steel.
Within the text of this specification and where appropriate, SI units are shown in parentheses. Where excessive cold working or tight bend radii cannot be avoided, the product should be stress relieved per the guidelines provided within ASTM A, Section 6. This abstract is a brief summary of the referenced standard. Factors in Warpage and Distortion 3. The design and fabrication of the product to be galvanized are the responsibilities of the designer and the fabricator.
Thls stendard Is subject to revision at any tlme by the responsible technical commHtee and must be reviewed every five years and H not revised, either reapproved or withdrawn.
Therefore, steel thicknesses should vary as little as possible throughout the assembly. Practice ASTM A provides guidance on safeguarding against warpage and distortion for optimum hot-dip galvanizing and shall be complied with in both design and fabrication.