Heat Exchanger Inspection and Testing

Heat Exchanger 1

These two heater exchangers (above and below) are the sames ones. This one has been wire wheeled, and or sanded. This process of cleaning, though common does not allow for a thorough inspection.

Heat Exchanger 2

Unlike in photo #1 the same area that was wire wheeled has now been blasted in our blast cabinet. The result is striking as far as how more efficient it is to bead blast a substrate than to just wire wheel to sand it. In this photo we can clearly see crevice corrosion starting up at the top right edge of the cooler. Furthermore, the red areas are very apparent. These red areas are unhealthy so to speak, as these areas of the bronze are in an advanced state of galvanic corrosion.

Removing, and visually inspecting a heat exchanger is only half of the service you can expect to receive from us. All of the related components that are able to be bead blasted, receive blasting in our blast cabinet. Bead blasting provides a 100% clean substrate for visual inspection. To not bead blast these items clean is to chance that a thorough visual inspection is not possible. We bead blast in order to ascertain the level of corrosion your parts may have that can affect the soundness of the part. Attempting to just sand, or wire wheel away paints, and corrosion is not very effective at all. See the two photos.

Additionally, we take your heat exchanger tube bundle, and install it into our pressure tester. See photo. 25 psi of air is pumped into the bundle, and then the entire unit is submerged in clean water. Any signs of leaking will become obvious.

“Why are parts of my heat exchanger turning that red color?” You are seeing Galvanic Corrosion. This is the most common cause of corrosion in the marine environment. Galvanic Corrosion is the interaction of two dissimilar metals in an electrolyte (saltwater). In this situation the least noble becomes the anode and corrodes. In this case you are seeing the depletion of the zinc in your bronze heat exchanger, thus leaving only the copper alloy. This is the red color you are seeing.

This is why it is so important that you keep your zincs in good fashion in your heat exchanger, if they are equipped with them.