The term “dual certification” refers to the practice of certifying one material as meeting the specification requirements of two different alloys. The most common materials that are dual certified are 304/304L and 316/316L. Dual certification is achieved by manufacturing the material to cover all requirements of both alloys. For example, the key differences between 316 and 316L are listed in the table below. 316/316L is manufactured to meet the low carbon content of 316L while also meeting the higher yield and tensile strength of 316.
| Alloy | Carbon (Wt %) | Yield Strength (psi) | Tensile Strength (psi) |
|---|---|---|---|
| 316 | 0.08 Max | 30,000 min | 75,000 min |
| 316L | 0.035 Max | 25,000 min | 70,000 min |
| 316/316L | 0.035 Max | 30,000 min | 75,000 min |
In addition to 304/304L and 316/316L, some other common alloys that are dual certified include:
- 304/304H
- 310S/310H
- 316/316H
- 317/317L
- 321/321H
- 347/347H
- 2205 (UNS S31803/S32205)
- 200/201
- 800H/800HT