What changes have occurred to the ASTM A325 specification since it was incorporated into the F3125 specification?

In December 2015, ASTM committee F16 approved the new F3125 standard, which combined six structural bolt standards, A325, A325M, A490, A490M, F1852, and F2280. The goal was to clean up inconsistencies within those various standards and combine them, so that future updates would be easier and less costly.

The goal was not to drastically change any of the requirements of the bolts, as they had been used and functioning in the marketplace for decades without major issues. However, in order to better align with each other and with current design standards, minor changes were made. The most notable change was the increase in mechanical properties of large diameter A325 bolts. Originally, bolts ½” through 1” diameter had a minimum tensile requirement of 120ksi, whereas for bolts above 1” diameter, the requirement dropped to 105ksi.  AISC design guides had used the 120ksi value for design loads all along regardless of bolt size, so this increase by ASTM aligns the design strength with the actual strength.

The table below outlines the mechanical changes. This is not meant to be a comprehensive comparison, there is much more information both on our website and within the F3125 standard at ASTM.org

Mechanical Requirements

A325 ½” – 1” A325 above 1” F3125 Gr.A325, all sizes
Tensile, min ksi 120 105 120
Yield, min ksi 92 81 92
Elongation, min % 14 14 14
RA, min % 35 35 35
Hardness, HBN 253-319 223-286 253-319

Additional Revisions

After much clamoring by the industry, a supplemental requirement was added to address alternate bolt configurations. Supplement S2 allows the purchaser to specify nonstandard dimensions for thread length, head style, etc. Bolts ordered to S2 are marked with an “S” to signify that these bolts vary from the ASME B18.2.6 dimensional standard, for example A325S.

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8 comments

    Good Day,

    As per my client requirement All bolts shall have a maximum Rockwell C hardness of 32, we have ASTM A193 B7, 316, & ISO 898-1 Gr. 10.9; however supplier says B7 Bolts Hardness can go up to a Max of 35 HRC and Gr. 10.9 has Min 32 HRC

    @Rajani- We are not sure what your question is here. If you are having trouble locating bolts that meet your customer’s requirement, you might need to go back and discuss options with your customer. Most of the grades you list span that hardness range, but you are correct that none have a hard cap at 32HRC.

    Dear Sir,
    I hope you are fine and doing well
    I am glad to be the part of this platform.
    My client’s requirement is mentioned below.Please suggest me what grade shall I quote.
    MACHINE BOLTS GRADE ASTM F3125, 1 No. HEAVY HEX NUT GRADE ASTM A563 WITH Washer 1No. ASTM F436/436M,HOT DIP SPUN GALVANIZED

    @Raj- ASTM F3125 has more than one grade, so you should clarify what they are needing. Normally the A490 grade is not galvanized, so I would assume that the A325 grade is what they want. The corresponding nut would be A563 grade DH.

    Dear Sir,
    Good day!
    I have question, That if purchaser do not mention the requirement as “Supplementary requirement” in purchase request for “Full Threaded” Bolt produced >4D. what will be head marking A325M or A325S ? where “S” is for special requirement as supplementary clauses S2.2.
    please confirm

    @Sajjad- If the bolt is manufactured with full thread, and it is 4x or less long, it should be marked A325T. If the bolt is longer than 4x, it should be marked A325S.

    Good day Dane,
    Thank you for posting this important message, I do have a query. The ASTM A325M-09 has the table 5, it shows the from M12 to M36 (Metric standard) the yield and tensile strength is same, so the revision in F3125 is only the standards that combines 4 different standards together to single platform. No difference in mechanical properties.

    Reference : ASTM A325M-2009 , Table 5. Pg 5.

    Your comment on this pls.

    @Sathish- There were six structural standards combined, A325, A325M, A490, A490M, F1852, and F2280. The idea behind combining them was for ease of maintenance and to clear up some conflicting language in the individual standards. With one small exception, none of the mechanical or chemical requirements were changed, they were simply combined into one standard. An A325M manufactured under A325M-09 shouldn’t be any different from one made per F3125-17 gr.A325M.

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