1.1 This specification covers tantalum and tantalum alloy seamless and welded tubes of the following grades:1.1.1 UNS Grade R05400 Unalloyed tantalum, powder-metallurgy consolidation,1.1.2 UNS Grade R05200 Unalloyed tantalum, vacuum melte This specification covers tantalum and tantalum alloy seamless and welded tubes of the following grades: UNS Grade R05400 which is unalloyed tantalum, powder-metallurgy consolidation, UNS Grade R05200 which is unalloyed tantalum, vacuum melted, UNS Gra