The standard stud for flanges and pressure piping — chrome-moly alloy, heat treated, and almost always paired with a 2H nut.
ASTM A193 Grade B7 is the workhorse alloy stud bolt for flanges and pressure piping — a heat-treated chromium-molybdenum steel (AISI 4140 family). Strength steps down a little as diameter goes up. It’s the stud half of the classic B7 stud + 2H nut flange combo.
Alloy studs for flanges & pressure
“B7” stamped on the end
Flange joints, pressure piping, high-temp
| Diameter | Tensile (min) | Yield (min) | Max hardness |
|---|---|---|---|
| ≤2½″ | 125 | 105 | 35 HRC |
| >2½–4″ | 115 | 95 | 35 HRC |
| >4–7″ | 100 | 75 | 35 HRC |
B7 studs make up flanged joints on pressure piping and vessels — the studs you run through both flanges with a nut on each end. They handle elevated temperature and pressure, which is why they show up across process piping and plant work. Count and size them from the flange stud & nut chart.
The standard mate is the A194 Grade 2H nut — two per stud.
Look for “B7” stamped on the end of the stud. They’re usually continuous-thread studs cut to length, threaded full length. For low-temperature service, a related spec (A320 L7) is used instead — ask if your job calls for cold service.
B7 stud bolts and all-thread cut to your flange, with the matching 2H nuts. Give us the flange size and class, or the stud length.
