A193 B8 Class 1 Stud Bolts
304 stainless bolting — Class 1 for corrosion resistance and cryogenic-to-1500 °F service, Class 2 strain hardened to 125 ksi for strength.
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.
ASTM A193 Grade B8 covers bolting made from AISI 304 austenitic stainless steel. Class 1 is carbide solution treated and has the modest 75 ksi strength of annealed 304 with the full corrosion resistance and toughness of the alloy from cryogenic temperatures to about 1500 °F. Class 2 is solution treated and then strain hardened, raising tensile strength to 125 ksi in small diameters at the cost of some ductility.
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What A193 B8 Class 1 must meet.
| Nominal diameter (in.) | Tensile strength, min (ksi) | Yield strength 0.2% offset, min (ksi) | Elongation in 4D, min (%) | Reduction of area, min (%) | Hardness, max |
|---|---|---|---|---|---|
| Class 1 — all diameters | 75 | 30 | 30 | 50 | 223 HBW / 96 HRB |
| Class 1A (B8A) — all diameters | 75 | 30 | 30 | 50 | 192 HBW / 90 HRB |
Values per ASTM A193/A193M-24, Tables 1 and 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Class 1 sizes ¾ in. and smaller may be 241 HBW / 100 HRB. Strain-hardened Class 2 and 2B properties are on the B8 Class 2 page.
Class 1: carbide solution treated. Class 1A (B8A): solution treated in the finished condition, 192 HBW / 90 HRB max. Class 2: solution treated then strain hardened, to 1½ in. Class 2B: strain hardened to lower strength levels in three size steps, 2 in. and under, over 2 to 2½ in., and over 2½ to 3 in.
Full A193 B8 Class 1 data sheet: chemistry, physical properties and standards →
Made to standard or to your drawing.
- Water treatment and waterworks flanges
- Food, beverage and pharmaceutical process equipment
- Cryogenic and LNG piping (Class 1)
- Architectural and marine-atmosphere hardware
- Chemical process piping in mild media
- Heat exchangers and stainless vessels