Full Thread Studs (Studbolts)
Threaded rod inserted through the holes of mating flanges, paired with heavy hex nuts.
Available in every diameter and length, imperial and metric, for flanged connections in critical service. Supplied bare or coated, with full material traceability.
Specifications & technical data.
Studbolts are our signature product — continuously threaded, chamfered both ends, cut to any length and paired with heavy hex nuts. Dimensions follow ASME B18.31.2; flange stud lengths follow ASME B16.5 by flange size and class.
Download our full thread stud dimensioning table (PDF)
| Nominal Size | D | Threads Per Inch | U — Chamfered Thread Distance | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| UNC | UNF | 8UN | UNC Threads | UNF Threads | 8UN Threads | |||||
| Min. | Max. | Min. | Max. | Min. | Max. | |||||
| 1/4" | 0.2500 | 20 | 28 | … | 0.050 | 0.100 | 0.036 | 0.071 | … | … |
| 5/16" | 0.3125 | 18 | 24 | … | 0.056 | 0.111 | 0.042 | 0.083 | … | … |
| 3/8" | 0.3750 | 16 | 24 | … | 0.063 | 0.125 | 0.042 | 0.083 | … | … |
| 7/16" | 0.4375 | 14 | 20 | … | 0.072 | 0.143 | 0.050 | 0.100 | … | … |
| 1/2" | 0.5000 | 13 | 20 | … | 0.077 | 0.154 | 0.050 | 0.100 | … | … |
| 9/16" | 0.5625 | 12 | 18 | … | 0.084 | 0.167 | 0.056 | 0.111 | … | … |
| 5/8" | 0.6250 | 11 | 18 | … | 0.091 | 0.182 | 0.056 | 0.111 | … | … |
| 3/4" | 0.7500 | 10 | 16 | … | 0.100 | 0.200 | 0.063 | 0.125 | … | … |
| 7/8" | 0.8750 | 9 | 14 | … | 0.111 | 0.222 | 0.072 | 0.143 | … | … |
| 1" | 1.0000 | 8 | 12 | … | 0.125 | 0.250 | 0.084 | 0.167 | … | … |
| 1-1/8" | 1.1250 | 7 | 12 | 8 | 0.143 | 0.286 | 0.084 | 0.167 | 0.125 | 0.250 |
| 1-1/4" | 1.2500 | 7 | 12 | 8 | 0.143 | 0.286 | 0.084 | 0.167 | 0.125 | 0.250 |
| 1-3/8" | 1.3750 | 6 | 12 | 8 | 0.167 | 0.333 | 0.084 | 0.167 | 0.125 | 0.250 |
| 1-1/2" | 1.5000 | 6 | 12 | 8 | 0.167 | 0.333 | 0.084 | 0.167 | 0.125 | 0.250 |
| 1-5/8" | 1.6250 | … | … | 8 | … | … | … | … | 0.125 | 0.250 |
| 1-3/4" | 1.7500 | 5 | … | 8 | 0.200 | 0.400 | … | … | 0.125 | 0.250 |
| 1-7/8" | 1.8750 | … | … | 8 | … | … | … | … | 0.125 | 0.250 |
| 2" | 2.0000 | 4-1/2 | … | 8 | 0.222 | 0.444 | … | … | 0.125 | 0.250 |
| 2-1/4" | 2.2500 | 4-1/2 | … | 8 | 0.222 | 0.444 | … | … | 0.125 | 0.250 |
| 2-1/2" | 2.5000 | 4 | … | 8 | 0.250 | 0.500 | … | … | 0.125 | 0.250 |
| 2-3/4" | 2.7500 | 4 | … | 8 | 0.250 | 0.500 | … | … | 0.125 | 0.250 |
| 3" | 3.0000 | 4 | … | 8 | 0.250 | 0.500 | … | … | 0.125 | 0.250 |
| 3-1/4" | 3.2500 | 4 | … | 8 | 0.250 | 0.500 | … | … | 0.125 | 0.250 |
| 3-1/2" | 3.5000 | 4 | … | 8 | 0.250 | 0.500 | … | … | 0.125 | 0.250 |
| 3-3/4" | 3.7500 | 4 | … | 8 | 0.250 | 0.500 | … | … | 0.125 | 0.250 |
| 4" | 4.0000 | 4 | … | 8 | 0.250 | 0.500 | … | … | 0.125 | 0.250 |
All dimensions in inches, per ASME B18.31.2-2014. U max = 2P, where P is the thread pitch. LT = nominal stud length. Flange stud lengths per ASME B16.5 — confirm requirements with our estimating team.
Standards.
What are full thread studs?
A full thread stud — the studbolt — is threaded continuously from end to end, chamfered at both ends, and made up with two heavy hex nuts. It is the fastener that holds flanged piping together: the thread runs the whole length so the nuts can land anywhere the joint stack-up requires.
- Continuous thread, both ends chamfered
- UNC, UNF and 8UN series — 8UN standard above 1″
- Cut to length in-house, any length, same day when it matters
- Typically supplied as an assembly with two heavy hex nuts
- B16.5 flange lengths by size and pressure class
Studbolts vs. threaded rod
A studbolt is a finished fastener: cut to a specified length, chamfered, certified to its heat, usually assembled with nuts. Threaded rod is the raw form — stock lengths you cut down yourself. When the joint is engineered — a flange, an exchanger, a valve bonnet — the studbolt is the specified product.
Other names
- Studbolts / stud bolts
- All-thread studs
- B7 studs
- Flange studs
- Continuous thread studs
Industries & applications
Oil & Gas
- Applications: flanged piping, wellheads, valve and exchanger bolting
- Materials: A193 B7 / B7M, A320 L7 / L7M, B16, super duplex
Offshore & Marine
- Applications: subsea flanges, splash-zone bolting with coatings
- Materials: PTFE-coated B7, Monel, super duplex 32760
Power Generation
- Applications: steam piping, high-temperature flange joints
- Materials: A193 B16, A453 660, Inconel 718
Tips for purchasing
- Call out diameter, thread series and length — for flanges, B16.5 sets the length from flange size and class; we can work it out from your flange list.
- Match the nuts — 2H with B7, Gr.7 with L7; we supply the set certified together.
- Name the coating — PTFE fluoropolymer, hot-dip galvanized, cad or plain oil finish.
- Sour service? Say so — B7M / L7M and NACE MR0175 requirements change the product.
- Full material test reports and heat traceability come standard.
Materials.
Representative capabilities — every item is manufactured or certified to your specification. Confirm requirements with our estimating team.
