Figure 3: Photo 1 was taken during an inspection with borescope of a condensate heat exchanger. Photo 2 and 3 are images observed in an optical microscope which reveal the morphology of the deposit.

According to some estimates, heat transfer coefficients with the twisted-tube design are 40% higher than those found in a conventional shell-and-tube heat exchanger with a similar pressure reduction.

ASTM A249 “Specification for welded austenitic steel boiler, super heater, heat exchanger, and condenser tubes” AS 1528.1 “Specification for tubes (stainless steel) for the food industry” AS1528 was ...