ASME SA213 T22 Serrated Fin With Tube For Heat Exchanger And Air Cooler

ASME SA213 T22 Base Tube Composition

Core Tube Material - SA312 T22 (Clarification & Correction):

• SA312: This ASME specification covers seamless and welded austenitic stainless steel pipes intended for high-temperature and general corrosive service.
• T22: This is NOT a grade typically listed under SA312. SA312 grades are like TP304, TP316, TP321, etc. (stainless steels).
• "T22" Confusion: T22 refers to a low-alloy steel (2.25% Chromium - 1% Molybdenum). It is a very common material for high-temperature service, but falls under specifications like:

ASME SA213 T22: For seamless ferritic and austenitic alloy-steel boiler, superheater, and heat-exchanger tubes.

ASME SA335 P22: For seamless ferritic alloy-steel pipe for high-temperature service.

• Conclusion: The core tube material is almost certainly SA213 T22 (if it's a tube) or SA335 P22 (if it's a pipe). It's a low-alloy steel known for good high-temperature strength, creep resistance, and oxidation resistance up to about 1050°F (565°C). It is not stainless steel.

Fin Type - Serrated Fins:

• Structure: Serrated fins start as a continuous helical fin (like an "L" or "LL" footed fin) wound onto the base tube. At regular intervals along the height of the fin, small sections are cut out or "notched" perpendicular to the fin's length.
• Key Visual Feature: Instead of being a smooth, continuous strip, the fin has a series of small, regular gaps or indentations along its edge, creating a "serrated" appearance (like a saw blade).
• Purpose of Serrations:

Enhanced Heat Transfer: The serrations disrupt the boundary layer formation of the fluid (usually gas like air or flue gas) flowing over the fins. This creates turbulence, breaking up the laminar sub-layer and significantly improving heat transfer efficiency compared to plain fins.

Reduced Weight & Material: The removed material slightly reduces the overall weight and cost compared to an equivalent solid fin.

• Trade-offs:

Slightly Higher Pressure Drop: The increased turbulence also increases the resistance to fluid flow (pressure drop) across the tube bundle.

Potential for Fouling: The notches can sometimes be more prone to trapping particulates in dirty gas streams compared to plain fins, though less so than studded fins.

Combined Description - SA213 T22 Tube with Serrated Fins:

• Core: A seamless tube manufactured to ASME SA213 T22 specifications, made of 2.25Cr-1Mo low-alloy steel.
• Fin: A helical fin mechanically bonded (usually tension-wound and footed) to the outer surface of the tube. This fin features regular notches cut perpendicularly along its height, creating the serrated edge profile.

SA213 T22 Serrated Fin Tube Application:

• Power Plants Heat Recovery Steam Generators (HRSGs): Economizers, Evaporators, Superheaters, Reheaters, Maximizes heat capture from exhaust gas. Air Heaters (Ljungström/Rothemühle), Coal/Gas-Fired Boilers Economizer sections (preheating feedwater) 
• Petrochemicals/Refineries: Process Heaters/Furnaces, Thermal Oxidizers/Incinerators Waste heat boilers
• Industrial Boilers Waste Heat Boilers Recovering heat from kilns, gas turbines, or chemical processes 
• Cement/Steel Preheaters & Coolers Heat recovery from kiln/kiln cooler exhaust gases