Engineering Reference
ASTM stud bolt and heavy hex nut pairing reference
Use this quick reference to match ASTM A193 and ASTM A320 stud bolts with the correct ASTM A194 heavy hex nuts for pressure equipment, industrial valves and low-temperature service.
Common grade pairings
| Stud Bolt Grade | Matching Nut Grade | Typical Service | Notes |
|---|---|---|---|
| ASTM A193 B7 | ASTM A194 2H | General high-temperature pressure equipment | Default pairing for refinery, valve and process flange joints. |
| ASTM A193 B7M | ASTM A194 2HM | Sour service / NACE MR0175 | Used where hardness control is required for H2S service. |
| ASTM A193 B16 | ASTM A194 7 | Elevated-temperature service | Typical for steam and higher-temperature process joints. |
| ASTM A193 B8 | ASTM A194 8 | General stainless service | Selected for corrosion resistance and clean-process duty. |
| ASTM A193 B8M | ASTM A194 8M | Chloride-bearing service | Preferred where stronger corrosion resistance is required. |
| ASTM A320 L7 | ASTM A194 7 | Low-temperature service | Common for cold-service and low-temperature pressure joints. |
| ASTM A320 L7M | ASTM A194 7M | Low-temperature sour service | Used where low temperature and hardness control both apply. |
Most-searched pairings
A193 B7 + A194 2HA320 L7 + A194 7B7M + 2HMB8M + 8M
FAQ
What nut is normally used with ASTM A193 B7 stud bolts?
ASTM A194 Grade 2H heavy hex nuts are the standard pairing for ASTM A193 B7 studs in many pressure-equipment and flange applications.
What nut is commonly matched with ASTM A320 L7?
ASTM A194 Grade 7 heavy hex nuts are commonly paired with ASTM A320 L7 studs for low-temperature service.
Why does the stud-and-nut pairing matter?
Correct pairing affects thread strength, preload reliability, temperature capability and compliance with the specified service conditions.