Rifled Tube

ARE YOU TAKING A TEST?

Please turn off the all-caps.

Rifled (enhanced) tubes make sense in contact with clean fluids of lower heat conductivity, such as air, oil, etc. I'm surprised to hear of their use in boilers, because they could be fouled by scale on the water side or soot on the fire side.

Internally rifled tubing is used in modern boilers to increase the heat transfer rate in certain sections. Fouling is less of a concern since the water condition is very tightly controlled.

See page 12 & 17 in this paper:

http://www.fwc.com/publications/tech_papers/files/TP_PC_07_01.pdf

For those of us who have never been inside a generating station reading the entire article will also give an excellent introduction onto the non-trivial amount of engineering and material selection that goes into modern power boiler design.