Here’s what’s typically used:

Common Heat Exchanger Tube Sizes

• Outer Diameter (OD):

  • 3/4 inch (19.05 mm) → Most common in shell-and-tube heat exchangers.

  • 1 inch (25.4 mm) → Often used for higher heat transfer surface or when fouling fluids are involved.

  • 5/8 inch (15.88 mm) → Used when compactness is important (like HVAC condensers and chillers).

  • Other sizes: 1.25", 1.5" OD exist for special designs, but are less common.

• Wall Thickness:

  • Standard ranges: BWG 14 to 20 (about 1.65 mm to 2.1 mm thick).

  • Thicker tubes (e.g., BWG 12) are used for high-pressure or erosive fluids.

• Tube Lengths:

  • Usually 6 ft to 24 ft (1.8 m to 7.3 m), depending on exchanger size.

  • Power plants and refineries may use tubes up to 30–40 ft.

• Materials:

  • Carbon steel, stainless steel (304, 316), copper alloys, admiralty brass, titanium, depending on the medium (steam, seawater, corrosive fluids).

Quick industry rule of thumb:

• 3/4” OD × 0.049” wall thickness × 20 ft length → the most widely used “standard” heat exchanger tube.

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