ASTM A193 Grade B7 Stud Bolt Chart — Size, Preload & Flange Pairing

Fastener chart compiled by cBallast. 1-page PDF; the full content is on this page.

Compiled by

cBallast

Subject

Alloy-steel stud bolt for flange service

Document type

Fastener chart

Reference

ASTM A193

Issued

2026-07-05

Pages

Format

Web page and PDF

ASTM A193 Grade B7 stud bolt chart: thread, tensile stress area, 50 % yield preload (kN), dry-thread torque (Nm) and the ASME B16.5 flange class / NPS pairing for stud sizes 1/2 in through 2-1/2 in. B7 is the default flange stud in the ASME B16.5 / B16.47 range — 4140/4142 alloy-steel, Class 2A UN thread, used with ASTM A194 Grade 2H heavy-hex nuts.

ASTM A193 Grade B7 Stud Bolt Chart — Size, Preload & Flange Pairing

ASTM A193 Grade B7 is the default flange stud in the ASME B16.5 / B16.47 range — an alloy-steel bolt in the 4140/4142 family, quench-and-tempered to 105 ksi (724 MPa) tensile strength and 105 ksi (724 MPa) yield up to 2 in, dropping to 100 / 95 / 75 ksi as the diameter steps up. The stud is threaded to Class 2A UN across the whole length and used with two ASTM A194 Grade 2H heavy-hex nuts.

Stud	Pitch	Tensile A (in²)	50 % Fy (kN)	Torque dry (Nm)	Flange pairing (ASME B16.5)
1/2 in	13 UNC	0.1419	45	140	ASME 150 NPS 3–8, EN PN10 DN15–100
5/8 in	11 UNC	0.2260	71	270	ASME 150 NPS 4–10, ASME 300 NPS 1–6
3/4 in	10 UNC	0.3345	106	475	ASME 150 NPS 6–24, ASME 300 NPS 2–10, ASME 600 NPS 1–8
7/8 in	9 UNC	0.4617	146	760	ASME 300 NPS 4–12, ASME 600 NPS 3–10
1 in	8 UNC	0.6057	191	1130	ASME 300 NPS 8–16, ASME 600 NPS 5–14, ASME 900 NPS 2–8
1-1/8 in	8 UN	0.7906	249	1580	ASME 300 NPS 12–24, ASME 600 NPS 8–18, ASME 900 NPS 4–14
1-1/4 in	8 UN	0.9691	305	2140	ASME 300 NPS 14–24, ASME 600 NPS 10–24, ASME 900 NPS 6–16
1-3/8 in	8 UN	1.1730	370	2830	ASME 600 NPS 14–24, ASME 900 NPS 8–20
1-1/2 in	8 UN	1.4030	442	3670	ASME 600 NPS 16–24, ASME 900 NPS 10–24, ASME 1500 NPS 3–8
1-5/8 in	8 UN	1.6600	523	4660	ASME 600 NPS 18–24, ASME 900 NPS 12–24
1-3/4 in	8 UN	1.9430	612	5810	ASME 900 NPS 16–24, ASME 1500 NPS 8–14
1-7/8 in	8 UN	2.2500	709	7130	ASME 600 NPS 24, ASME 900 NPS 20–24
2 in	8 UN	2.5800	813	8640	ASME 1500 NPS 10–18
2-1/4 in	8 UN	3.2500	1020	12200	ASME 1500 NPS 14–24
2-1/2 in	8 UN	4.0000	1260	16800	ASME 1500 NPS 16–24, ASME 2500 NPS 6–12

Torque and preload

Torque values are for K = 0.20 dry threads at 50 % of specified minimum yield. Lubricated with anti-seize (K = 0.16): multiply the torque by ~0.75. Never re-use a B7 stud loaded to 50 % Fy — the elastic history changes the K factor.

Frequently asked questions

How many B7 studs does an ASME 150 flange take?: It varies by size — the chart maps each stud diameter to its flange range: 1/2 in studs serve ASME 150 NPS 3–8 patterns, 5/8 in studs NPS 4–10, and so on with length per flange class.
What is the tensile capacity of a 1/2 in B7 stud?: With a 0.1419 in² stress area, about 45 kN at proof-level loading — the chart lists capacity and torque per diameter.
B7 or B7M — what is the difference?: B7M is the controlled-hardness (max 235 HB) variant for sour/H2S service per NACE MR0175; it torques lower than standard B7.
Which nuts pair with B7 studs?: ASTM A194 2H heavy hex nuts — the standard companion grade, also covered in the chart's pairing notes.

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Compiled by cBallast for identification and cross-reference. Part numbers, designations and trademarks belong to their respective manufacturers. Confirm ratings and dimensions against the manufacturer's current documentation and the nameplate of the installed equipment before ordering or installation.