ASTM A-335 P5 Finned Tubes: Technical Specifications and Applications

1. What is ASTM A-335 P5 Fin Tube?

ASTM A-335 P5 finned tubes are longitudinally welded or seamless chrome-molybdenum alloy steel pipes (5% chromium, 0.5% molybdenum) with externally attached fins. These tubes combine the high-temperature strength of P5 alloy (Grade P5 per ASME Section I/II) with enhanced heat transfer surfaces, designed for service temperatures up to 650°C in corrosive environments.

2.ASTM A-335 P5 Fin Tube Manufacturing Process

2.1 Base Tube Production

• Electric resistance welding (ERW) or seamless extrusion of Cr-Mo alloy steel
• Normalization heat treatment at 900-950°C
• Non-destructive testing (UT/ET for welds, hydrostatic testing)

2.2 Fin Attachment Methods

• High-Frequency Welded Fins: G-fin process with continuous helical wrapping
• Embedded Fins: L-foot fins mechanically bonded into milled grooves
• Extruded Fins: Integral fins formed through cold working (max 12.5mm height)

3. What is the production principle of ASTM A-335 P5 Fin Tube?

The metallurgical synergy between P5 alloy and fins follows:

• Coefficient of thermal expansion matching (11.5 μm/m·°C at 20-600°C)
• Oxide layer formation (Cr2O3) provides corrosion resistance
• Fin efficiency calculations based on Fourier’s Law (typical η > 85%)

4. What are the advantages of ASTM A-335 P5 Fin Tube?

• Thermal Performance: 3-8x higher heat flux than bare tubes
• Mechanical Properties:
  • Tensile strength: ≥415 MPa at room temperature
  • Creep resistance: 10,000h rupture strength of 110MPa at 600°C
• Economic Benefits: 30-50% reduction in heat exchanger footprint

5. ASTM A-335 P5 Fin Tube Application Cases

5.1 Petrochemical Industry

• Delayed coker units at SINOPEC Zhenhai Refinery (China):
  • Service: 540°C heavy oil flow
  • Configuration: φ50.8×6.3mm base tube with 16mm aluminum fins
  • Service life: >8 years without replacement

5.2 Power Generation

• Flue gas heat recovery in Drax Power Station (UK):
  • Operating parameters: 580°C, 3.5MPa
  • Material savings: 280 tons/year per boiler
  • Efficiency gain: 2.3% plant thermal efficiency improvement

5.3 Waste Heat Recovery

• Cement plant preheater (LafargeHolcim Mexico):
  • Gas inlet: 700°C (short-term), continuous 650°C
  • Fin type: Serrated stainless steel overlay
  • Payback period: