Boiler Bank tubes

Product Description

Boiler Bank Tubes Complete Guide

Boiler bank tubes, also known as generating bank tubes, are a central part of the steam generation system in water-tube boilers. They connect the steam drum and the mud drum and play a vital role in producing saturated steam by transferring heat from flue gases to the circulating water inside the tubes.

What Are Boiler Bank Tubes?

Boiler bank tubes are straight or slightly curved water tubes arranged in parallel rows (banks) between the upper steam drum and the lower mud drum. They're exposed primarily to convection heat from the flue gases, and their main purpose is to:

• Generate saturated steam

• Complete the water/steam circulation loop

• Improve boiler efficiency

Typical Arrangement:

• Position: Located between the furnace and economizer, in the convective pass of the boiler.

• Orientation: Generally vertical, but some boilers may use slightly inclined tubes for circulation efficiency.

• Tube Banks: Often arranged in multiple rows (front and rear) to increase heat transfer surface.

Design & Material:

• Tube Material: Usually carbon steel (e.g., SA-210 Gr A1, SA-192) or low alloy steel

• Tube OD: Common sizes include 38 mm (1.5"), 50.8 mm (2"), 63.5 mm (2.5")

• Wall Thickness: Varies depending on pressure rating, usually 2.5 mm 4.5 mm

• Length: Custom to boiler height

• Connection: Expanded or welded into steam and mud drums

 Working Principle:

1. Feedwater enters the mud drum.

2. Water rises through boiler bank tubes, absorbing heat from the flue gases.

3. As water heats up, steam starts forming inside the tubes.

4. The steam-water mixture reaches the steam drum, where steam separates from water.

5. Steam continues to superheater, while water recirculates back.

Function in Boiler Efficiency:

• Provides major surface area for heat exchange.

• Operates in subcooled boiling region, meaning water partially turns to steam.

• Acts as a thermal buffer between high-radiant heat areas (furnace) and lower-temp components (economizer).

Maintenance & Inspection:

• Soot blowing to clean external tube surfaces

• Descaling or chemical cleaning of internal deposits

• Ultrasonic testing for wall thickness

• Hydro testing for pressure integrity

• Visual inspection through drum manholes

Boiler Bank vs Other Boiler Tubes:

Quality & Standards:

• Manufactured to ASME or EN standards

• Test certificates for material chemistry, tensile, and hydro tests

• Proper tube pitch and alignment are critical for performance and flow distribution