ASME SA335 P9 Studded Finned Tubes for Process Fired Heaters

ASME SA335 P9 Studded Finned Tubes are high-temperature heat transfer tubes designed for process fired heaters, refinery furnaces, and petrochemical heating equipment. Manufactured with a seamless SA335 P9 alloy steel base tube and externally welded studs, these tubes provide increased heat transfer surface while maintaining the mechanical strength required for demanding high-temperature service.

The P9 base tube is an 8–10% chromium, molybdenum-alloyed ferritic steel developed for high-temperature applications. Its Cr-Mo composition provides improved resistance to high-temperature oxidation and good mechanical stability compared with conventional carbon steel, making it suitable for demanding furnace and convection-section applications.

The studded configuration creates a dense external heat-transfer surface and is particularly suitable for convection sections where effective gas-side heat transfer is required. Stud dimensions, pitch, arrangement, and stud material can be customized according to heater design, operating conditions, and project specifications.

Key Features

• Base Tube Material: ASME SA335 P9 seamless alloy steel
• Application: Process fired heaters, refinery furnaces, petrochemical heaters, and convection sections
• Fin Type: Welded stud / pin fin
• High-Temperature Service: Designed for elevated-temperature heat transfer applications
• Custom Stud Configuration: Stud diameter, height, pitch, and arrangement can be manufactured according to project requirements
• Project-Based Engineering: Tube dimensions and stud configuration can be matched to the customer's heater design
• Inspection Documentation: Material certificates, dimensional inspection, visual inspection, stud attachment inspection, and other tests can be provided according to the approved ITP

Applications

ASME SA335 P9 Studded Finned Tubes are mainly used in high-temperature heat-transfer equipment, particularly:

• Process Fired Heaters
• Refinery Furnaces
• Petrochemical Furnaces
• Furnace Convection Sections
• Heater Convection Banks
• High-Temperature Heat Recovery Sections
• Oil & Gas Processing Plants
• Petrochemical Processing Facilities

Chemical Composition of ASME SA335 P9

The following chemical composition is based on the SA335/A335 P9 grade requirements:

The relatively high chromium content, combined with molybdenum, is a defining characteristic of P9 and contributes to its suitability for high-temperature alloy-steel service.

Mechanical Properties of ASME SA335 P9