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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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. This is not true of an I-beam, pipe, H-column, or any other section that is symmetrical about both its major axes.
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. Necessary precautions to fabricate properly and prepare the material for galvanizing to prevent embrittlement are described in Practice A Wherever possible, galvanize thick and thin portions separately and join them after galvanizing. Factors in Warpage and Distortion 3.
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.
After galvanizing, these products should be air cooled instead of quenched to minimize induced stress from the cooling cycle. Therefore, steel thicknesses should vary as little as possible throughout the 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. 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 year of last revision.
This specification deals with safeguarding against warpage and distortion during hot-dip galvanizing of steel assemblies. Last previous edition A – 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.
These rivets can be countersunk or flat head if the protruding head of the ordinary button or round head rivet is objectionable. The design and fabrication of the product to be galvanized are the responsibilities of the designer and the fabricator.
Clamps may be applied to prevent shifting or movement during the welding operation.
It is recommended that welding procedures be carried out in conformancewith the pertinent specificationsof the American Welding Society. 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.
ASTM A384 Recommendations
Specify symmetrically rolled sections instead of angle or channel frames. Originally published as A – 55 T.
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A number in parentheses indicates the year of last reapproval. 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.
Historical Version s – view previous versions of standard. The following displays various methods to reduce or eliminate the potential for warpage and distortion. 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. 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
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. This abstract is a brief summary of the referenced standard.
This will prevent the rusting of the surfaces which are so connected aastm molten zinc cannot circulate through the crevices to galvanize the contacting surfaces.
Current edition approved Oct.
Suggested corrections for panel fabrication are detailed. Welding results in significant residual stress in small areas of an assembly due to the extreme temperature differences experienced.
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.
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. The following can cause warpage and distortion: Additionally, the installation of diagonal members should be performed after galvanizing.