ASTM A325 Structural Steel Bolts, Heat Treated

ASTM A325 Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength

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Hardness Requirements for Bolts

Bolt Size, in.	Bolt Length, in.	Brinell		Rockwell C
Bolt Size, in.	Bolt Length, in.	Min	Max	Min	Max
1⁄2 to 1, incl	Less than 2 D ^A	253	319	25	34
	2 D and over	. . .	319	. . .	34

11⁄8 to 11⁄2 , incl	Less than 3 D ^A	223	286	19	30
	3 D and over	. . .	286	. . .	30
^A Sizes 1.00 in. and smaller having a length shorter than 2 Dand sizes larger than 1.00 in. having a length shorter than 3 D are subject only to minimum and maximum hardness.
D = Nominal diameter or thread size.

Tensile Load Requirements for Full-Size Bolts

Bolt Size, Threads per Inch, and Series Designation	Stress Area, ^A in.²	Tensile Load, ^B min, lbf	Proof Load, ^B Length Measurement Method	Alternative Proof Load, ^B Yield Strength Method
Column 1	Column 2	Column 3	Column 4	Column 5
1⁄2 –13 UNC	0.142	17 050	12 050	13 050
5⁄8 –11 UNC	0.226	27 100	19 200	20 800
3⁄4 –10 UNC	0.334	40 100	28 400	30 700
7⁄8 –9 UNC	0.462	55 450	39 250	42 500
1–8 UNC	0.606	72 700	51 500	55 750
11⁄8 –7 UNC	0.763	80 100	56 450	61 800
11⁄8 –8 UN	0.790	82 950	58 450	64 000
11⁄4 –7 UNC	0.969	101 700	71 700	78 500
11⁄4 –8 UN	1.000	105 000	74 000	81 000
13⁄8 –6 UNC	1.155	121 300	85 450	93 550
13⁄8 –8 UN	1.233	129 500	91 250	99 870
11⁄2 –6 UNC	1.405	147 500	104 000	113 800
11⁄2 –8 UN	1.492	156 700	110 400	120 850
^A The stress area is calculated as follows: As = 0.7854 [ D - (0.9743/n)]²
where: As = stress area, in.²; D = nominal bolt size, and n = threads per inch.

^B Loads tabulated are based on the following:

Bolt Size, in.	Column 3	Column 4	Column 5
1⁄2 to 1, incl	120 000 psi	85 000 psi	92 000 psi
11⁄8 to 11⁄2 , incl	105 000 psi	74 000 psi	81 000 psi

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