1.1 This specification covers heat-treated carbon-manganese-silicon steel plates intended for fusion welded pressure vessels and structures.

1.2 Plates furnished under this specification are available in the following three classes:

			Yield	Tensile
			Strength,	Strength,
	Heat	Thickness,	min, ksi	min, ksi
Class	Treatment		[MPa]	[MPa]
1	Normalized	2½ in. and under [65 mm and under]	50 [345]	70 [485]
		Over 2½ to 4 in. [Over 65 to 100 mm]	45 [310]	65 [450]
2	Quenched and tempered	2½ in. and under [65 mm and under]	60 [415]	80 [550]
		Over 2½ to 4 in. [Over 65 to 100 mm]	55 [380]	75 [515]
		Over 4 to 6 in. [Over 100 to 150 mm]	46 [315]	70 [485]
3	Quenched and tempered	2½ in. and under [65 mm and under]	55 [380]	80 [550]
		Over 2½ to 4 in. [Over 65 to 100 mm]	50 [345]	75 [515]
		Over 4 to 6 in. [Over 100 to 150 mm]	40 [275]	70 [485]

1.3 The maximum thickness of plates furnished under this specification is 4 in. [100 mm] for Class 1 and 6 in. [150 mm] for Class 2 and Class 3.

1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system is to be used independently of the other without combining values in any way.