Thermal Plate Heat Exchangers

Jacket or Immersion Plate

A dimple jacket is embossed on one side only. The flat side is welded, bonded or clamped to the outside of the tank wall, hold bulkhead or hull plating, and the dimpled side carries the refrigerant or coolant. The tank wall itself becomes the heat transfer surface, nothing sits in the product, and the inside of the hold stays a smooth, washable surface with no plates to work around when loading or unloading.

An immersion plate is embossed on both sides and hangs free in the tank on brackets, so both faces are working surface and the plate can be fitted to an existing hold without hot work on the shell. It gives more surface per plate and is easy to retrofit; the jacket gives a clear tank and no fouling at all. Most holds use one or the other, some use both, and we will say which suits the tank you have.

A hold full of seawater and fish, or a brine tank at well below the freezing point of fresh water, is about as aggressive as marine service gets. The water is cold, salty, oxygen-starved under a load of fish, and loaded with organic matter, and stainless steel in those conditions pits and crevice-corrodes at the welds. Titanium does not. It is immune to chloride attack at every temperature a hold will see and is not eroded by ice or scoured surfaces.

Stainless steel earns its place on fresh water and clean process duty, where the chloride is absent and cost matters. The choice is made per duty, and it is not one to compromise on: a plate that pits through inside a hold puts refrigerant into the catch. Our Stainless Steel in Seawater notes explain where the line falls.