2013 HDG Specification Updates
What are the new changes to ASTM A123?
The new changes to ASTM A123/A123M-13, Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products are part of the continuing evolution of the specification to accurately depict the outcome of industry practices to produce quality galvanized products and to tweak the language to make it more understandable and objective.
ASTMs A05.13 subcommittee, which is chaired by our AGA Technical Director Dr. Tom Langill, is wholly responsible for the oversight of our most critical specification, ASTM A123. Because of his influence and persuasive argument, the specification issued this past week reflects the reality of our business; it is difficult to achieve coating thickness on some steel plate thicknesses due to the steel chemistry of the plate material in thicknesses below 5/8. The same is true for strip and bar products which are made from plate material.
As it appears in the revised specification, the table below reflects new coating grades for plate steel, which is now a separate material category from structural shapes, new coating thicknesses for strip and bar, and a new column for steel thickness of >5/8 (16 mm) for all material categories.
ASTM A123 TABLE 1: MINIMUM AVERAGE COATING THICKNESS BY MATERIAL CATEGORY
| Material Category | All Specimens Tested- Steel Thickness Range (Measured), in. (mm) | |||||
|---|---|---|---|---|---|---|
<1/16 [<1.6] | >1/16 to <1/8 [>1.6 to <3.2] | >1/8 to <3/16 [>3.2 to < .8] | >3/16 to <1/4 [>4.8 to <6.4] | >1/4 to <5/8 [>6.4 to <16.0] | >5/8 [>16.0] | |
| Structural Shapes | 45 | 65 | 75 | 75 | 100 | 100 |
| Strip and Bar | 45 | 65 | 75 | 75 | 75 | 100 |
| Plate | 45 | 65 | 75 | 75 | 75 | 100 |
| Pipe and Tubing | 45 | 45 | 75 | 75 | 75 | 75 |
| Wire | 35 | 50 | 60 | 65 | 80 | 80 |
| Reinforcing Bar | - | - | - | - | 100 | 100 |
The highlight of the changes is plate and strip and bar < 5/8 thick now have a minimum coating grade of 75 which will ease the burden many galvanizers have to meet the specification. This is especially true for those galvanizers processing steel that is aluminum killed, which has very low silicon content and on the other end of the reactive steel spectrum.
If you haven't looked at Table 1 for a while you may also notice a change made in 2012. That change added a reinforcing bar as a material category and was done to address the deficiency of ASTM A767 which did not provide a coating thickness requirement for reinforcing steel used in a weldment with, for example, plate embedments.
The other changes to A123 are simple text changes but significant in that they modify paragraph 7.3 to replace the words test specimens with test articles so the paragraph is in agreement with what is represented in Figure 1 of the specification.
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