| HT-21 | Heat Treatment of Carbon and Alloy Steels up to 200,000 psi | Heat Treat |
| Superseded by: None | Superseded By: None | |
| Selected sector: AS | Date added: | |
| SupplierNumber | SupplierName | State | CountryName |
| 90203122 | Accurate Steel Treating Inc. | CA | United States |
| 90049129 | BODYCOTE THERMAL PROCESSING | CA | United States |
| 90055923 | BODYCOTE THERMAL PROCESSING | CA | United States |
| 90049444 | CERTIFIED STEEL TREATING CORP | CA | United States |