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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Clamps may be applied to prevent shifting or movement during the welding operation. It is recommended that welding procedures be carried out in conformancewith asgm pertinent specificationsof the American Welding Society. It is informational only and q384 an official a834 of the standard; the full text of the standard itself must be referred to for its use and application.
The design and fabrication of the product to be galvanized are the responsibilities of the designer and the fabricator. 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 astmm axis – aligning welds so that shrinkage and opposing forces are balanced rather than all pulling in the same direction.
Current edition approved Oct. 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.
The following can cause warpage and distortion: Within the text of this specification and where appropriate, SI units are shown in parentheses. A number in parentheses indicates the year of last reapproval.
In the case of sheet metal, the product which has a right-angle bend in the sheet metal itself will remain flatter and be freer from distortion if the radius of the bend a38 as large as practicable. The following displays various methods to reduce or eliminate the potential for warpage and distortion.
Common distorted and warped members of assemblies are sheets or plates assembled by welding or riveting. 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. 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. 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.
Inch pounds and SI units are not necessarily exact equivalents. 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.
A superscript epsilon E indicates an editorial change since the last revision or reapproval. In nearly every case, regardless of size, channels require straightening after galvanizing. This is not true of an I-beam, pipe, H-column, or any other section that is symmetrical about both its major axes.
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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. Suggested corrections for panel fabrication are detailed.
Channels and other nonsymmetrical sections should be avoided a34 the framework of a sheet metal assembly that is to be hot-dip galvanized whenever it is possible to use symmetrical shapes or sections.
This specification deals with safeguarding against warpage and distortion during hot-dip galvanizing of steel assemblies.
ASTM A384 Recommendations
Last previous edition A – Therefore, steel thicknesses should vary as little as possible throughout the assembly. 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. This will prevent the rusting of the surfaces which are so connected that molten zinc cannot circulate through the crevices to galvanize the contacting surfaces.
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 abstract is a brief summary of the referenced standard. Specify symmetrically rolled sections instead of angle or channel frames. Link to Active This link will always route to the current Active version of the standard.
Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters.
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. 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.
All efforts should be made to keep the stresses in the construction as low as possible right from the beginning to enable the steel to absorb the internal stresses completely.
Furthermore, cylindrical structures are less likely to warp or distort than rectangular or elliptical ones.
Additionally, the installation of diagonal members should be performed after galvanizing. Welding results in significant residual stress in small areas of an assembly due to the extreme temperature differences experienced. Steel invariably contains internal stresses induced at the mill from rolling operations used to bring structures, plate, and sheet to the final thickness.
Factors in Warpage and Distortion 3. Suggested Corrections for Panel Fabrication 4. 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.
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. Necessary precautions to fabricate properly and prepare the material for galvanizing to prevent embrittlement are described in Practice A Originally published as A – 55 T.
The overall amount of welding can be minimized by using bolted connections or performing assembly after hot-dip galvanizing. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ASTM A Recommendations | American Galvanizer’s Association
These rivets can be countersunk or flat head if the protruding head of the ordinary button or round head asgm is objectionable. 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.
Wherever possible, galvanize thick and thin portions separately and join them after galvanizing. Historical Version s – view previous versions of standard.