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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Inch pounds and SI units are not necessarily exact equivalents. Thls stendard Is subject asfm revision at any tlme by the responsible technical commHtee and must be reviewed every five years and H not revised, either reapproved or withdrawn. ASTM does not give a34 warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.
Additionally, the installation of diagonal members should be performed after galvanizing. It is recommended that welding procedures be carried out in conformancewith the pertinent specificationsof the American Welding Society.
Furthermore, cylindrical structures are less likely to warp or distort than rectangular or elliptical ones. Historical Version s – view previous versions of standard.
ASTM A384 Recommendations
Where welding before galvanizing cannot be w384, 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.
Therefore, steel thicknesses should vary as little as possible throughout the assembly.
The following can cause warpage and distortion: In welding any intermediate sstm 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.
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The design and fabrication of the product to be galvanized are the responsibilities of the designer and the fabricator. 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.
In nearly every case, regardless of size, channels require straightening after galvanizing. Factors in Warpage and Distortion 3.
ASTM A _图文_百度文库
Suggested corrections for panel fabrication are detailed. Necessary precautions to fabricate properly and prepare the material for galvanizing to prevent embrittlement are described in Practice A All efforts should be made to keep the stresses astn the construction as low as possible right from the beginning to enable the steel to absorb the internal stresses completely.
Specify symmetrically rolled sections instead of angle or channel frames. Welding results in significant residual stress in small areas of an assembly astj to the extreme temperature differences experienced.
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. The following displays various methods to reduce or eliminate the potential for a34 and distortion. Suggested Corrections for Panel Fabrication 4.
Steel invariably contains internal stresses induced at the mill from rolling operations used to bring structures, plate, and sheet to the final thickness. 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 adtm of last revision.
A number in parentheses indicates the year of last reapproval. 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.
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. Minimize A348 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. Asymmetrical Design Symmetrical sections such as I-beams and tubing will be less likely to distort than asymmetrical pieces camber beams, channels, tees, custom qstm, girders because the thermal expansion forces above and below the natural axes balance each other.
It is informational only and not an official part of the standard; the full text of the standard adtm must be referred to for its use and application. Originally published as A – 55 T. Common distorted and warped members of assemblies are sheets or plates assembled by welding or riveting. Avoid Susceptible Thin Sheet Steels Steel aatm contains internal stresses induced at the mill from rolling operations used to bring structures, plate, and sheet to the final thickness.