Do A325 Bolts Sometimes Run Short on Length?

The answer is yes, A325 structural bolts very often run around 1/8” short.

It is important to realize that ASTM A325 Structural bolts fall into a class of their own and cannot be compared to other fastener Grades. These bolts are designed specifically for steel-to-steel connections. Because the application is so specific, they have dimensional properties that are unique and very limited.

Here are a few of the things that are unique to A325 bolts:

- Length tolerances allow for bolts lengths to be .12” - .25” under the published length.

- The thread Lengths are shorter than most other grades.

- Available in Heavy Hex Head only

- Stock sizes are very limited. This specification only covers diameters ½” – 1-1/2”

As you can see, ASTM A325 is very restrictive. For Bolts over 1-1/2” diameter it is impossible to make them to the A325 specification. Bolts over 1-1/2” diameter must be manufactured per A449.

The A449 specification has the identical mechanical properties of A325, however many of the restrictions are lifted. Most notably, A449 allows for variable thread lengths, alternate head styles and covers diameters up to 3.”

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