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A contractor is stating that the nut and bolt that we are requiring is not to be spec. together.  Please review page 20 of the attached link.

<http://roadwaystandards.dot.wi.gov/standards/cmm/110.pdf>

"Post bolts are 5/8" diameter x 1'6" long ASTM A307 button head bolt. A post bolt requires a 5/8" diameter A563 DH heavy hex nut and a 5/8" diameter F436 flat washer."

This lists an A563 DH nut and a F436 flat washer. Technically, these are the nut and washer spec for A325 bolts. This is what we typically have listed on our details.

Because the A307 bolt is less strong than an A325, it is allowed to use lower strength nuts and washers. These are the A563A Heavy Hex and the F844 washer. Thus, this is the standard nut and bolt combo. What we typically use is stronger.

http://www.portlandbolt.com/technicalinformation/astm/ASTM_A307.html

Use of the A563A Heavy Hex and the F844 washer is perfectly ok and meets the AASHTO Hardware guide listing for the bolts.