1.1 This specification2 covers carbon steel plates intended primarily for service in welded pressure vessels where improved notch toughness is important.
1.2 Plates under this specification are available in four grades having different strength levels as follows:
| 8201;Grade U.S. [SI] | Tensile Strength, |
| 55 [380] | 55–75 [380–515] |
| 60 [415] | 60–80 [415–550] |
| 65 [450] | 65–85 [450–585] |
| 70 [485] | 70–90 [485–620] |
1.3 The maximum thickness of plates is limited only by the capacity of the composition to meet the specified mechanical property requirements; however, current practice normally limits the maximum thickness of plates furnished under this specification as follows:
| 8201;Grade U.S. [SI] | Maximum Thickness, |
| 55 [380] | 12 [305] |
| 60 [415] | 8 [205] |
| 65 [450] | 8 [205] |
| 70 [485] | 8 [205] |