JIS G3462 — Alloy steel pipes for boilers and heat exchangers
Grades
STBA12, STBA13, STBA20, STBA22, STBA23, STBA24, STBA25, STBA26
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| STBA12 | C≤0.15, Mn 0.30-0.60, P≤0.030, S≤0.030, Si 0.10-0.50, Cr 0.80-1.25, Mo 0.45-0.65 | Rm ≥385 MPa, Rp0.2 ≥205 MPa, A≥30% |
| STBA13 | C≤0.15, Mn 0.30-0.60, P≤0.030, S≤0.030, Si 0.50-1.00, Cr 1.00-1.50, Mo 0.45-0.65 | Rm ≥415 MPa, Rp0.2 ≥205 MPa, A≥30% |
| STBA20 | C≤0.15, Mn 0.30-0.60, P≤0.030, S≤0.030, Si 0.50-1.00, Cr 1.00-1.50, Mo 0.45-0.65 | Rm ≥415 MPa, Rp0.2 ≥205 MPa, A≥30% |
Application scope
JIS G3462 specifies seamless alloy steel tubes for boilers and heat exchangers, primarily composed of chromium-molybdenum alloys, and are typically delivered after normalizing and tempering. Grades include STBA12, STBA13, STBA20, etc., with varying chromium-molybdenum content, resulting in corresponding improvements in high-temperature strength, creep resistance, and heat resistance.
Typical applications
Mainly used in high-temperature pressure-bearing components such as superheater tubes, reheater tubes, and high-temperature heat exchanger tubes in power plant boilers. Chromium-molybdenum alloy seamless tubes have good high-temperature strength and creep resistance, making them suitable for heat-receiving surface tube banks, serpentine tubes, and high-temperature heat transfer tube bundles that serve for long periods under high-temperature conditions. They are commonly used alloy steel tubes in the high-temperature section and high-temperature heat exchange of boilers.
