Marine heat exchanger cleaning

Usually yes, where the cooler can be isolated against a standby unit and the deposit is one that circulation will shift. A central cooler on a duty-standby pair is the straightforward case: the offline unit is circulated, rinsed and returned while the vessel works cargo.

It stops being possible where there is no standby, where the deposit is marine growth, not scale, or where the window is shorter than the circulation needs to be. Growth in particular does not dissolve on a useful timescale. It has to be physically removed.

Mechanically, and generally out of the water. Barnacle and mussel shell is a structure and not a deposit, and no circulation removes it at a rate that fits a port call. Scraping, brushing and jetting take the bulk off, and acid circulation afterwards deals with the calcareous base left on the tube surface.

That makes box cooler and sea chest cleaning drydock work in most cases. Where a diving contractor can work the sea chest in port, the growth can be reduced, but the tube nest itself is not properly reached in the water.

They widen what the plates themselves tolerate and they do not change what the rest of the unit tolerates. Titanium handles seawater and aggressive acid cleaning that would pit stainless, so it is specified for seawater duty in the first place.

The limits move to the gaskets, the frame, the studs and the connected pipework. A chemistry chosen for the plate material alone can destroy a gasket set, so the clean is specified for the whole assembly.

Cleaning is not itself a class matter, but the condition it reveals often is. A stripped pack that shows thinning, pitting or cracking generates findings, and coolers opened for survey have to be presented in a state the surveyor can assess.

What a clean should produce is the record: what was found, what was replaced, what was tested and to what pressure. Where the work is being done to support a survey, say so in the enquiry, because it changes what has to be documented and when.

An in-place chemical clean on the air side is typically a matter of hours and can be done between port calls where the engine can be taken off load. It restores some duty and it does not reach a heavily loaded fin block.

Removing the cooler and immersing it is the thorough version and takes days rather than hours, because the cooler has to come out, soak, be rinsed, dried, tested and refitted. On a vessel with no spare that means planning it into a docking.

Sometimes, and it depends entirely on redundancy. Where there is a standby cooler and the crew can isolate it, a circulation clean on passage is routine and is the least disruptive way to do it.

Riding crew work of this kind needs the vessel's agreement, the permits, and confined space arrangements where machinery space entry is involved. It also needs somewhere to put the spent cleaning solution, which cannot go over the side.

The same three things decide it as anywhere else, unit, deposit and access, but access carries far more weight at sea. A central cooler circulated alongside with ship's connections is one price. The same cooler landed, stripped, cleaned, gasketed, tested and returned is a different one entirely.

Port, window and whether a spare exists are what move the number most, so the enquiry asks for the port and the timescale instead of just the unit.

By measurement, not by calendar. Differential pressure across the cooler and the temperature difference across it are the two figures worth trending, and both are usually already being logged.

In practice seawater duties foul far faster than shoreside equivalents, and vessels trading in warm, shallow or estuarine waters foul fastest of all. Trading pattern predicts fouling rate better than running hours do.