BOLT MARKINGS AND STRENGTH (US)
| Head Marking | Grade & Material | Size Range (inches) | Mechanical Properties Proof Load (psi) | Mechanical Properties Min. Yield Strength (psi) | Mechanical Properties Min Tensile (psi) |
|---|---|---|---|---|---|
 No Markings | Grade 2 Low or Medium Carbon Steel | 1/4" - 3/4" Above 3/4"-1 1/2" | 55,000 33,000 | 57,000 36,000 | 74,000 60,000 |
 3 Radial Lines | Grade 5 Medium Carbon Steel | 1/4"-1" Above 1" - 1 1/2 | 85,000 74,000 | 92,000 81,000 | 120,000 105,000 |
 6 Radial Lines | Grade 8 Medium Carbon Steel | 1/4"-1 1/2" | 120,000 | 130,000 | 150,000 |
| Stainless Steel Markings Vary | 18-8 Stainless Steel Alloy with 17-19% Chromium & 8-13% Nickel | Up to 1" | - | 20,000 Min. 65,000 Typical | 65,000 Min. 100,000-150,000 Typical |