ASTM A307 Bolting Specification

Carbon Steel Bolts, Studs, Stud Bolts, and Threaded Rod 60 000 PSI Tensile Strength

ASTM A307 Hex Bolts, Heavy Hex Bolts, Studs, Socket Head Cap Screws, Threaded Rods

ASTM A307 covers two grades of carbon steel bolts and studs in sizes 1/4 inches through 4 inches. Threaded rod is not usually produced to Grade B, but at Torqbolt we can produce them as and when required by our customers. Bolting type such as Hex Bolts, Heavy Hex Bolts, Studs, Socket Head Cap Screws, Hex Cap Screws, Threaded Rods and Threaded Bars can be manufactured from ¼” to 4” in imperial and M6 to M100 in metric variants both fine threads and coarse threads. Bolting Components up to 6” can be provided at TorqBolt with the same certification. PED 2014/68/EC Certified ASTM/ASME A307 is available exstock.

Scope

Grade	Description
ASTM 307 Grade A	Bolts, studs, and threaded rod having a minimum tensile strength of 60 ksi and intended for general applications,
ASTM 307 Grade B	Bolts, studs, and threaded rodA having a tensile strength of 60 to 100 ksi and intended for flanged joints in piping systems with cast iron flanges, and
ASTM 307 Grade C	Replaced by Specification f1554Gr.36
(A) Nuts of other grades and styles having specified proof load stresses (Specification A563) greater than the specified grade and style of nut are also suitable.

Fastener Grade and Size	Nut Grade and StyleA
A 1/4 to 11/2 in.	A, hex
A over 11/2 to 4 in.	A, heavy hex
B, 1/4 to 4 in.	A, heavy hex
(A) Nuts of other grades and styles having specified proof load stresses (Specification A563, Table 3) greater than the specified grade and style of nut are also suitable.

ASTM A307 Chemical Composition

Elements	Heat Analysis	Product Analysis
Carbon, max	0.29	0.33
Manganese, max	1.20	1.25
Phosphorus, max	0.04	0.041
Sulfur, max	...	...
Grade A	0.15	A
Grade B	0.05	0.051
(A) Resulfurized steel is not subject to rejection based on product analysis for sulfur.

ASTM A307 Mechanical Properties

Hardness Requirements for Bolts, Studs, and Threaded Rod

Grade	Nominal Length, in.	HardnessA
		Brinell		Rockwell B
		min	max	min	max
ASTM A307 A	Less than 3 × diaB	121	241	69	100
	3 × dia and longer	. . .	241	. . .	100
ASTM A307 B	Less than 3 × diaB	121	212	69	95
	3 × dia and longer	. . .	212	. . .	95
(A) As measured anywhere on the surface or through the cross section. (B) Also bolts with drilled or undersize heads. These sizes and bolts with modified heads shall meet the minimum and maximum hardness as hardness is the only requirement.

Tensile Requirements for Full-Size Bolts, Studs, and Threaded Rod

Bolt Size, in.	Threads per inch	Stress Area,A in.2	Tensile Strength, lbfB
			Grade A, min C	Grade B
				minD	maxD
1/4	20	0.0318	1 900	1 900	3 180
5/16	18	0.0524	3 100	3 100	5 240
3/8	16	0.0775	4 650	4 650	7 750
7/16	14	0.1063	6 350	6 350	10 630
1/2	13	0.1419	8 500	8 500	14 190
9/16	12	0.182	11 000	11 000	18 200
5/8	11	0.226	13 550	13 550	22 600
3/4	10	0.334	20 050	20 050	33 400
7/8	9	0.462	27 700	27 700	46 200
1	8	0.606	36 350	36 350	60 600
11/8	7	0.763	45 800	45 800	76 300
11/4	7	0.969	58 150	58 150	96 900
13/8	6	1.155	69 300	69 300	115 500
11/2	6	1.405	84 300	84 300	140 500
13/4	5	1.90	114 000	114 000	190 000
2	41/2	2.50	150 000	150 000	250 000
21/4	41/2	3.25	195 000	195 000	325 000
21/2	4	4.00	240 000	240 000	400 000
23/4	4	4.93	295 800	295 800	493 000
3	4	5.97	358 200	358 200	597 000
31/4	4	7.10	426 000	426 000	710 000
31/2	4	8.33	499 800	499 800	833 000
33/4	4	9.66	579 600	579 600	966 000
4	4	11.08	664 800	664 800	1 108 000

Tensile Requirements for Machined Specimens

Tensile Requirements	Grade A	Grade B
Tensile strength, ksi	60 min	60-100
Yield point, min ksi	. . .	. . .
Elongation in 2 in., min, %	18	18

Over Tapped Nut Limits

Unless otherwise specified, bolts, studs, and threaded rod to be used with nuts or tapped holes which have been tapped oversize, in accordance with Specification A563, shall have threads as specified in B1.1 before hot-dip or mechanically deposited zinc coating. After zinc coating the maximum limit of pitch and major diameter shall not exceed the Class 2A maximum limit by more than the following amounts

Diameter, in.	Oversize Limit, in.A
1/4	0.016
5/16 , 3/8	0.017
7/16 , 1/2	0.018
9/16 to 3/4 , incl	0.020
7/8	0.022
1.0 to 11/4 , incl	0.024
13/8 , 11/2	0.027
13/4 to 4.0, incl	0.050
(A) These values are the same as the overtapping required for zinc-coated nuts in Specification A563.

ASTM A307 Bolting Surface Treatment Specifications

ASTM A307 Bolting Components Marking

Product Shall be Marked with our manufacturing trade mark "TorqBolt" or "TB" along with the designated Grade.
Grade and manufacturer’s identification symbols shall be applied to one end of studs and to the heads of bolts and screws of all sizes. (If the available area is inadequate, the grade symbol may be marked on one end and the manufacturer’s identification symbol marked on the other end.) For bolts and screws smaller than 1⁄4 in. [6 mm] in diameter and studs smaller than 3⁄8 in. [10 mm] in diameter and for 1⁄4 in. [6 mm] in diameter studs requiring more than a total of three symbols, the marking shall be a matter of agreement between the purchaser and the manufacturer.

Grade	Marking
A	TB 307A
B	TB 307B

ASTM A307 Supplementary Requirements