Fin Count: Always in multiples of four (4, 8, 12, etc.).  Maximum fin count is a function of tube OD and can be estimated by dividing the tube circumference by 0.15 and rounding up or down to the nearest multiple of 4.

  

Production: Fin strip is uncoiled, formed into U-shaped channels, and cut to the required length.  Each leg of the channel is a fin.  The channels are then oriented along the length of the tube in diametrically opposite pairs and electric resistance welded using high speed automatic machinery.

Services: Virtually unlimited.  Typically used in longitudinal flow applications such as pipe-in-pipe exchangers, tank suction heaters, etc.  Ideal for vertical installations and high pressure and temperature applications.