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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Thls stendard Aatm 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by the responsible technical commHtee and must be reviewed every five years and H not revised, either reapproved or withdrawn. This is not true of an I-beam, pipe, H-column, or any other section that is symmetrical about both its major axes. Practice ASTM A provides asstm on safeguarding against warpage and distortion for optimum hot-dip galvanizing and shall be complied with in both design and fabrication.
Minimize Thick and Thin Material in the Same Assembly When two steels of different thicknesses are assembled and brought up to galvanizing temperature, awtm 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. 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.
Current edition approved Oct. 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. 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.
Welding results in significant residual stress in small areas of an assembly due to the extreme temperature differences experienced. Last previous edition A – After galvanizing, these products should be air cooled instead of quenched to minimize induced stress from the cooling cycle.
ASTM A Recommendations | American Galvanizer’s Association
Steel invariably contains internal stresses induced at the mill from rolling operations used to bring structures, plate, zstm sheet to the final thickness.
Suggested corrections for panel fabrication are detailed. 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. 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.
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 astk, girders because the thermal expansion forces above and below the natural axes balance each other.
The design and fabrication of the product to be galvanized are the responsibilities of the designer and the fabricator. Link to Active This link will always route to the current Active version of the standard. 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. Clamps may be applied to prevent shifting or movement during the welding operation.
Furthermore, cylindrical structures are less likely to warp or distort than rectangular or elliptical ones. Therefore, steel thicknesses should vary as little as possible throughout the astn.
Factors in Warpage and Distortion 3. Within the text of this specification and where appropriate, SI units are shown in parentheses.
Oftentimes sheet or plate can be returned to a flattened state using a jig or by weighing qstm product down on a flat surface during the cool-down. These rivets can be countersunk or flat head if the protruding head of the ordinary button or round head rivet is objectionable.
Suggested Corrections for Panel Fabrication 4. This specification deals with safeguarding against warpage and distortion during hot-dip galvanizing of steel assemblies.
A number in parentheses indicates the year of last reapproval.
Specify symmetrically rolled sections instead of angle or channel frames. 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.
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.
Additionally, the installation of diagonal members should be performed after galvanizing. 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.
The following can cause warpage and distortion: The following displays various methods to reduce or eliminate the potential for warpage and distortion. Necessary precautions to fabricate properly and prepare the material for galvanizing to prevent embrittlement are described in Practice A 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.
ASTM A384 Recommendations
This will prevent the rusting of the surfaces which are so connected that molten zinc cannot circulate through the crevices asttm galvanize the contacting surfaces.
This abstract is a brief summary of the referenced standard. Originally published as A – 55 T. It is recommended that welding procedures be carried out in conformancewith the pertinent specificationsof the American Welding Society. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. The overall amount of welding can be minimized by using bolted connections aetm performing assembly after hot-dip galvanizing.
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. 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.
Historical Version s – view previous versions of standard. Inch pounds and SI units are not necessarily exact equivalents. In nearly every case, regardless of size, channels require straightening after galvanizing. 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.
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.