1.1 This specification covers seamless ferritic and austenitic steel boiler, superheater, and heat-exchanger tubes, designated Grades T5, TP304, etc. These steels are listed in Tables 1 and 2. 1.2 Grades containing the This specification covers seamless ferritic and austenitic steel boiler, superheater, and heat-exchanger tubes. Grades containing the letter H in their designation have requirements different from those of similar grades not containing the letter H. Th