Question 1

During your oral exam you are asked to explain the basic operating principle of a plate heat exchanger used for, e.g., lubricating oil or jacket water cooling, and what symptoms might indicate fouling or a developing leak between the two fluid sides.

Accepted Answer

Two fluids flow through alternating channels separated by thin corrugated plates, transferring heat through the plate material without mixing; fouling typically presents as reduced heat transfer efficiency (outlet temperatures drifting toward inlet temperatures) and increased pressure drop, while a plate/gasket leak may present as cross-contamination — for example, seawater entering a freshwater cooling circuit, detectable by salinity testing or unexpected level changes in expansion tanks Plate heat exchangers rely on close-fitting gasketed (or brazed/welded) plates to keep the two fluid circuits separate while maximising surface area for heat transfer, and fouling — typically biological growth or scale on the seawater side — reduces transfer efficiency progressively, often first noticed as the cooled-side outlet temperature creeping upward. A plate or gasket failure allowing cross-contamination is a serious fault, particularly seawater ingress into a freshwater jacket cooling system, which can cause corrosion damage and is typically first detected through routine coolant salinity/chloride testing — a key reason this testing forms part of routine engine room watchkeeping.

Question 2

You're draining a thermal oil system that was running normally a short time ago. Before opening the drain point, what should you confirm?

Accepted Answer

That the system has cooled and depressurised, and you are positioned clear of the drain point's discharge path On the dredger MV Amazone, two crew members draining a thermal oil system after months of contamination were sprayed with hot oil, suffering severe burns. The investigation found company procedures lacked clear instructions for safe drainage — confirming the system has cooled and depressurised, and standing clear of the discharge path, are essential before opening any drain point on a hot oil system.

Question 3

A thermal oil system has been contaminated and needs draining for cleaning. The written procedure tells you to open the drain valve but doesn't specify a cooling-down period or PPE. What should you do?

Accepted Answer

Treat the gap as a hazard in its own right: apply a suitable cooling/depressurising period and full PPE before proceeding, and raise the procedure gap with the Chief Engineer The FEBIMA investigation into the MV Amazone incident found that although the crew followed company procedures, those procedures lacked clear instructions for safely draining a thermal oil system. A procedure that's silent on cooling time and PPE for a hazardous task is a gap to be closed before the job starts — not a green light to skip those precautions.