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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ASTM A384 Recommendations
Wherever possible, galvanize thick and thin portions separately and join them after galvanizing. Suggested Corrections for Panel Fabrication 4. This abstract is a brief summary of the referenced standard.
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 in the construction as low as possible right from the beginning to enable the steel to absorb the internal stresses completely.
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. 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.
A superscript epsilon E indicates an editorial change since the last revision or reapproval.
After galvanizing, these products should be air cooled instead of aatm to minimize induced stress from the cooling cycle. Common distorted and warped members of assemblies are sheets or plates assembled by welding or riveting. 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.
ASTM does not give any warranty express or implied or make any representation that the contents of this a3844 are accurate, complete or up to date. 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. A number in parentheses indicates the year of last reapproval.
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. Welding results in significant residual stress in small areas of an assembly due to the extreme temperature differences experienced.
These rivets can be countersunk or flat head if the protruding head of astk ordinary button or round head rivet is objectionable. 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.
Within the text of this specification and where appropriate, SI units are shown in parentheses.
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. Suggested corrections for panel fabrication are detailed.
Specify symmetrically rolled sections instead of angle or channel frames. The following can cause warpage and distortion: Additionally, the installation of diagonal members should be performed after galvanizing.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. The design and fabrication of a834 product to be galvanized are the responsibilities of the designer and the fabricator.
ASTM A _图文_百度文库
The overall amount of welding can be minimized by using bolted connections or performing assembly after hot-dip galvanizing. 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.
Link to Active This link will always asstm to the current Active version of the standard. Inch pounds and SI units are not necessarily exact equivalents.
This specification deals with safeguarding against warpage and distortion during hot-dip galvanizing of steel assemblies. Optimize Welding Before Hot-Dip Galvanizing Welding results in significant residual stress in small areas of awtm assembly due to the extreme temperature differences experienced.
Steel invariably contains internal stresses induced at the mill from rolling operations used to bring astmm, plate, and sheet to the final thickness. In nearly every case, regardless of size, channels require straightening 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.
Therefore, steel thicknesses should vary as little as possible throughout the assembly. It is recommended that aastm procedures be carried out in conformancewith the pertinent specificationsof the American Welding Society. The following displays various methods to reduce or eliminate the potential awtm warpage and distortion.
Channels and other nonsymmetrical sections should be avoided for the framework of a sheet metal assembly that is to be hot-dip galvanized whenever axtm is possible to use symmetrical shapes or sections. Originally published as A3884 – 55 T. 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.
Clamps may be applied to prevent shifting or movement during the welding operation. Furthermore, asym structures are less likely to warp or distort than rectangular or elliptical ones. 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.
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 satm 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.
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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. Last previous edition A – 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.
In welding any intermediate lengths along one atm of a common member, care should zstm 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.
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. Factors in Warpage and A3884 3.
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. Current edition approved Oct.