ASTM A213 T12 containing the letter H in their designation have requirements different from those of similar grades not containing the letter H.
These different requirements provide higher creep-rupture strength than normally achievable in similar grades without these different requirements. ASTM A213 T12 tubes shall be made by the seamless process and shall be either hot finished or cold finished, as specified. Grade TP347HFG shall be cold finished. Heat treatment shall be done separately and in addition to heating for hot forming. The ferritic alloy and ferritic stainless steels shall be reheated. On the other hand, austenitic stainless steel tubes shall be furnished in the heat-treated condition. Alternatively, immediately after hot forming, while the temperature of the tubes is not less than the minimum solution temperature, tubes may be individually quenched in water or rapidly cooled by other means. Tension test, hardness test, flattening test, and flaring test shall be done to each tube. Also, each tube shall be subjected to the nondestructive electric test or hydrostatic test.

ASTM A209 Through A213

• Other standard specifications include the categories of A209 seamless carbon-molybdenum alloy-steel boiler and superheater tubes; A210 seamless medium-carbon steel boiler and superheater tubes and A213 seamless ferritic and austenitic steel boiler, superheater and heat-exchanger tubes.
• Piping wall thicknesses range from 1/2 inch to 5 inches.
• ASTM A213 grades also have the letter H or M assigned, which changes the composition and specifications for that series.

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