Knowledge base
In short
On ships, offshore platforms and coastal plants, the engine is usually cooled by a closed fresh water circuit, and a plate heat exchanger passes that heat to sea water. Sea water stays in one short, well protected part of the system and never reaches the engine. TECS Engineering designs and delivers plate heat exchanger solutions for these duties.
At sea the cooling medium is free and unlimited, and it is also the worst liquid an engine could be asked to meet. Sea water carries salt, sand, shells and marine growth, and it attacks most of the metals an engine is made of. That is why a ship, an offshore platform or a power plant on the coast rarely lets sea water near the engine. A plate heat exchanger stands in between, and this guide explains why it is the usual choice there and what a buyer is asked when ordering one.
Keeping Sea Water Away From The Engine
The common arrangement is called central cooling. The engine and its auxiliaries are cooled by a closed fresh water circuit, treated and kept clean. That circuit gives its heat to a plate heat exchanger, and sea water pumped from outside carries the heat away on the other side. The sea water stays in a short section of pipe, a pump, a strainer and the exchanger, and goes back overboard.
Everything else in the plant - the engine jackets, the oil coolers, the charge air coolers, the generators - sees only fresh water. Fewer parts meet salt, fewer parts corrode, and the long internal pipework can be built from ordinary materials.
Why Plates Rather Than Tubes
Space decides a great deal on board. An engine room or a platform module has little room to spare, and a plate exchanger does the same job in a much smaller footprint than a tube cooler, with less liquid inside and less weight to carry. Where the duty grows, a gasketed unit can often take more plates in the same frame.
The second reason is service. Marine growth and silt settle in any cooler that sea water passes through. A gasketed plate unit can be opened in place, the plates cleaned and the gaskets checked, without pulling a tube bundle out of a cramped room. Many plants fit two exchangers side by side so that one is cleaned while the other carries the load.
What Sea Water Asks Of The Exchanger
The plates on the sea water side must be made of a material that does not suffer in salt water; ordinary stainless steel is not enough there, and titanium is the usual answer. The gaskets, the frame coating and the connections need the same care. A good strainer ahead of the exchanger keeps shells, weed and sand out of the narrow channels, and a dosing system against marine growth is common on larger plants.
Ships and offshore installations also bring paperwork of their own. The owner or the classification society usually sets rules for materials, testing and documents, and these belong in the enquiry from the start rather than after the order.
On Board, Offshore And On The Coast
The same idea serves propulsion engines and generator sets on ships, power and process modules on offshore platforms, and engine or turbine plants built on the shore that draw their cooling from the sea or a harbour. Where sea water is not available or not allowed, the fresh water circuit goes instead to an air-cooled radiator. TECS Engineering designs and delivers plate heat exchanger solutions for engine, power plant and industrial cooling circuits; send the engine data, the sea water conditions and the rules that apply, and the engineering team will answer.
In Short
- Central cooling: a closed fresh water circuit for the engine, sea water only in the exchanger
- Sea water stays in a short, protected section of the plant
- Plates save space and weight in engine rooms and platform modules
- Gasketed units are opened and cleaned in place
- Sea-water-resistant plates, a good strainer and growth control are standard
- Classification and owner rules belong in the enquiry from the start
What To Send With An Enquiry
- Engine or plant data with the heat to be removed
- Where the unit goes: ship, offshore platform or coastal plant
- Sea water conditions: source, quality and how much silt or growth to expect
- The fresh water circuit and any glycol mixture
- Space, weight limits and access for cleaning
- Classification, material and test requirements
Questions We Are Often Asked
Why not cool a marine engine directly with sea water?
Sea water corrodes the engine and fouls its passages. A closed fresh water circuit protects the engine, and a plate heat exchanger passes the heat to the sea water.
What is central cooling on a ship?
An arrangement where all engines and auxiliaries are cooled by one fresh water circuit, which gives its heat to sea water in a central plate heat exchanger.
Which plate material is used for sea water?
Usually titanium, because ordinary stainless steel can corrode in salt water. The gaskets and the frame are chosen for sea water too.
How is marine growth kept out of the exchanger?
With a strainer ahead of the unit, a dosing system against growth on larger plants and regular cleaning of the plates.
What should I send to get an offer?
The engine data, where the unit is installed, the sea water conditions, the fresh water circuit, the space and the classification or owner requirements.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
