ASTM A335 Grade P9 Alloy Steel Seamless Pipe Chrome Moly Pipe for High-Temperature Service
ASTM A335 / ASME SA335 Grade P9 Cr-Mo Alloy Steel Seamless Pipe Black Painted
ASTM A335 Grade P9 / UNS K90941 is a seamless 9Cr-1Mo chrome-moly alloy steel pipe for high-temperature service. It is used in boiler superheater/reheater piping, steam lines, headers, and refinery/power-plant piping. It offers good oxidation resistance and moderate high-temperature strength, but it is less common than P11, P22, and P91. For boiler tubes, the equivalent tube specification is usually ASTM A213 T9. Always verify the latest ASTM A335/A335M or ASME SA335 requirements and the specific purchase-order requirements before ordering or fabricating.
Note: For boiler tubes, the common matching grade is ASTM A213 T9.
A335 P9 is generally pipe for high-temperature piping systems; A213 T9 is tube for boilers, superheaters, and heat exchangers. Chemistry is similar, but the product specification and testing differ.
Equivalent Material of ASTM A335/ASME SA335 Grade P9 Alloy Steel Seamless Pipe
| UNS | ASTM | EN | DIN | JIS | GB |
| K90941/S50400 | P9 | 12Cr9Mo | X12CrMo91 | STBA26 | / |
Chemical composition(%) of ASTM A335/ASME SA335 Grade P9 Alloy Steel Seamless Pipe
| Grade | C | Mn | P≤ | S≤ | Si≤ | Cr | Mo |
| P9 | ≤0.15 | 0.30-0.60 | 0.025 | 0.025 | .25-1.00 | 8.00-10.00 | .90-1.10 |
Mechanical Property of ASTM A335/ASME SA335 Grade P9 Alloy Steel Seamless Pipe
| Steel Grade | Tensile Strength, Mpa | Yield Strength, Mpa | Elongation, % |
| P9 | Min: 415 | Min: 205 | Min: 30 |
Limitations of Grade P9 Alloy Steel
-
Less common than P11, P22, and P91.
-
Lower creep strength than P91 / P92.
-
More expensive and harder to weld than P11 or P22.
-
Requires controlled preheat, interpass temperature, and post-weld heat treatment.
-
Not a stainless steel; it is an alloy steel because Cr is below about 10.5%.
-
Can be sensitive to embrittlement and requires proper heat treatment.
Application
-
Boiler superheater and reheater piping
-
Main steam piping and steam headers
-
High-temperature power-plant piping
-
Refinery and petrochemical high-temperature piping
-
Heat exchanger and heat-transfer piping in some services
-
Furnace and high-temperature process equipment
-
Hydrogen service where 9Cr-1Mo is suitable
For boiler tubes specifically, the matching tube grade is usually ASTM A213 T9.
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.