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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This is not true of an I-beam, pipe, H-column, or any other section that is symmetrical about both its major axes.
Wherever possible, galvanize thick and thin portions separately and join them after galvanizing. 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. Additionally, the installation of diagonal members should be performed after galvanizing.
ASTM A384 Recommendations
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. 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.
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. 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 is as large as practicable. 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.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. 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. Welding results in significant residual stress in small areas of an assembly due to the extreme temperature differences experienced. In nearly every case, regardless of size, channels require straightening after galvanizing.
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This abstract is a brief summary of the referenced standard. Inch pounds and SI units are not necessarily exact equivalents. Necessary precautions to fabricate properly and prepare the material for galvanizing to prevent embrittlement are described in Practice A This specification deals with safeguarding against warpage and distortion during hot-dip galvanizing of steel assemblies.
The overall amount of welding can be minimized by using bolted connections or performing assembly after hot-dip galvanizing.
ASTM A _图文_百度文库
Originally published as A – 55 T. The design and fabrication of the product to be galvanized are the responsibilities of the designer and the fabricator. Specify symmetrically rolled sections instead of angle or channel frames. 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. Furthermore, cylindrical structures are less likely to warp or distort than rectangular or elliptical ones.
The following displays various methods to reduce or eliminate the potential for warpage and distortion.
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. Last previous edition A – 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.
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. Historical Version s – view previous versions of standard. After galvanizing, these products should be air cooled instead of quenched to minimize induced stress from the cooling cycle. These rivets can be countersunk or zstm head if the protruding head of the ordinary button or round head rivet is objectionable.
It is informational only and not astj official part of the standard; the full text of the standard itself must be referred to for its use and application. 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.
Within the text of this specification and where appropriate, SI units are shown in parentheses.
ASTM A Recommendations | American Galvanizer’s Association
The following can cause warpage and distortion: 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. Current edition approved Oct.
It is recommended that welding procedures be carried out in conformancewith the pertinent specificationsof the American Welding Society. 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. A number in parentheses indicates the year of last reapproval.
Common distorted and warped members of assemblies are sheets or plates assembled by welding or riveting. 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, awtm assembled to the galvanized frame by the use of aluminum alloy or galvanized rivets.