What causes a heat exchanger to leak internally?

Internal leaks in a heat exchanger can primarily be attributed to issues with the gaskets, as they play a crucial role in maintaining a seal between the various sections of the heat exchanger. When a gasket is ripped or damaged, it can no longer effectively separate the two fluids flowing through the heat exchanger. This failure can lead to the mixing of the fluids, resulting in an internal leak.

The gaskets are designed to withstand specific pressures and temperatures, and any wear and tear, degradation due to chemical exposure, or improper installation can compromise their integrity. When the gasket is compromised, it allows the fluids to escape from their designated channels, causing an internal leak that can affect system performance and lead to further complications.

Other factors listed, like loose bolts, cold fluids, or warm fluids, typically do not directly cause internal leaks. Loose bolts may lead to a failure in the entire structure or external leaks rather than internal, while the temperature of the fluids alone doesn't inherently create a leak. The condition of the gaskets is critical for the heat exchanger's integrity and functionality.