Common Heat Transfer Fluid Problems

Problem Cause Consequence
Oxidative Degradation -Exposure of Heat Transfer Fluid to air leads to an oxidation reaction that degrades the fluid over time.– Absence of blanketing with an inert gas (e.g N2,Ar) – Increase in viscosity (decrease in heat transfer efficiency)– Increase in Total Acid Number (TAN). Leads to corrosion problems if moisture is present

– Fouling/Formation of sludge (fouling decreases heat transfer efficiency and increases maintenance costs)

– Fluid discoloration

See our recommendation on Oxidative degradation in the article, ‘Solutions to Heat Transfer Fluid Problems’

Thermal Cracking -Heating a Heat Transfer Fluid above its bulk temperature of the heat transfer fluid results in a cracking of the fluid. A rapid rise in burner/boiler temperature can also crack the fluid.– Low flow

– Improper flame impingement


– Decrease in viscosity, flash point, fire point and autoignition temperature (safety concern)– Carbon varnishes foul heat transfer surface

– Fluid has pungent/sharp smell

See solution in the article, ‘Solutions to Heat Transfer Fluid Problems’

See our recommendation on thermal cracking in the article, ‘Solutions to Heat Transfer Fluid Problems’

Contamination – Pipe/vessel leaks may cause process to enter into the Heat Transfer Fluid causing/accelerating fluid degradation– Water may get into the expansion tank

– Poor drainage and flushing of degraded Heat Transfer Fluid before replacement with new fluid.

-Rapid fluid degradation– Corrosion

– Pump cavitation (in a case where water vapor is converted to steam as temperature is increased)

– There could also be adverse effects on fluid viscosity, volatility and heat transfer efficiency

See our recommendations on fluid contamination in the article, ‘Solutions to Heat Transfer Fluid Problems’