This specification covers several grades of minimum wall thickness, seamless, carbon-molybdenum alloy steel, boiler and superheater tubes.
SIZE RANGE
Outside diameter : 1/2 to 5 in. (12.7 to 127 mm) .
Minimum wall thickness : 0.035 to 0.500 in. (0.9 to 12.7 mm).
MANUFACTURE
The steel shall be killed.
The tubes shall be made by the seamless process and shall be either hot finished or cold-finished as specified.
All tubes shall be heat treated.
CHEMICAL REQUIREMENTS
| Grade | Designatio UNS | Carbon | Manganese | Phosphorus | Sulfur | Silicon | Molybdenum | ||||||||||||||||||||||||||||||||
| % | % | maxi % | maxi % | % | % | ||||||||||||||||||||||||||||||||||
| T1 | – | 0.10 / 0.20 | 0.30 / 0.80 | 0.025 | 0.025 | 0.10 / 0.50 | 0.44 / 0.65 | ||||||||||||||||||||||||||||||||
| T1a | – | 0.15 / 0.25 | 0.30 / 0.80 | 0.025 | 0.025 | 0.10 / 0.50 | 0.44 / 0.65 | ||||||||||||||||||||||||||||||||
| T1b | – | 0.14 maxi | 0.30 / 0.80 | 0.025 | 0.025 | 0.10 / 0.50 | 0.44 / 0.65 | ||||||||||||||||||||||||||||||||
TENSILE REQUIREMENTS
| Grade | Tensile strength mini | Yield strength mini | Elongation mini in 2 in. or 50 mm | Hardness maxi | |||||||||||||||||||||||||||||||||||
| ksi | MPa | ksi | MPa | % | Brinell | Rockwell | |||||||||||||||||||||||||||||||||
| T1 | 55 | 380 | 30 | 205 | 30 | 146 HB | 80 HRB | ||||||||||||||||||||||||||||||||
| T1a | 60 | 415 | 32 | 220 | 30 | 153 HB | 81 HRB | ||||||||||||||||||||||||||||||||
| T1b | 53 | 365 | 28 | 195 | 30 | 137 HB | 77 HRB | ||||||||||||||||||||||||||||||||
GENERAL REQUIREMENTS
To specification ASTM A 450 / A 450 M-96a.
