Getting it Wrong
What is the most expensive thing you use to wash a cargo tank? It isn’t water.
It is getting the cleaning wrong.
Reliable data related to costs of cargo claims due to contamination isn’t broadly published, yet all the major insurers are on record as stating it is a lot of money. A lot.
For a tanker carrying a cargo worth $10 million, $20 million or even more, a small amount of residue, salt or contamination from a previous cargo can have very serious consequences.
Failing a cargo inspection
A failed cargo inspection can lead to:
• Re-cleaning
• Delayed loading
• Off-hire
• Cargo reprocessing
• Shore storage
• Ship-to-ship transfer
• Disposal or salvage
• Legal and expert costs
• And potentially a multi-million-dollar cargo claim
Yet we still tend to think about tank-cleaning water primarily in terms of cost per tonne.
Perhaps we should be thinking about it in terms of risk per tonne.
Reverse Osmosis
Not all “fresh water” is the same
This is where Reverse Osmosis deserves more attention.
A modern marine RO system can produce large volumes of technical water with very low salinity and very low TDS directly from seawater.
Why does that matter?
Because when you’re trying to remove the remnants of a previous cargo, the last thing you want to do is introduce unnecessary dissolved salts and minerals during the washing and rinsing process.
RO gives the vessel a consistent supply of high-quality, low-salinity water specifically for technical applications.
And that doesn’t mean using valuable potable water for everything.
Potable water is for people.
Technical water is for technical applications.
Cargo-tank cleaning is a technical application.
The Numbers
Let’s put a number on it
Take a vessel that needs 200 m³ of water for a tank-cleaning operation.
Assume a modern RO system consumes approximately 8 kWh per m³.
200 m³ × 8 kWh/m³ = 1,600 kWh
At an electricity cost of $0.15/kWh, the energy required to produce that water is approximately:
$240.
Even allowing for periodic membrane replacement, maintenance, equipment depreciation and other operating costs, the cost of producing the water remains relatively small.
Now compare that with the potential consequences of getting the cleaning wrong.
A $5 million cargo claim would be more than 20,000 times the $240 energy cost of producing those 200 tonnes of RO technical water.
In Summary
The RO plant isn’t only producing water for one tank-cleaning operation.
It can also provide technical water for:
Deck washing | Machinery | Boiler applications | General technical use
So the investment isn’t simply about producing cheaper water.
It’s about giving the vessel control over the quantity and quality of the water it needs.
Water is cheap. Cargo isn’t.
At Stonefort Marine, we work with specialist RO designers and manufacturers who are, quite literally, water nerds.
We enjoy the difficult challenges and focus only on designing solutions that meet the exact end-user needs.
After all, a tanker carrying millions of dollars of cargo shouldn’t necessarily be relying on the same water strategy it has always used.
The cheapest water on the ship may be the water that prevents the most expensive mistake.
If you’re reviewing your vessel’s water production capacity, tank-cleaning requirements or technical-water strategy, let’s have a conversation.
#Shipping #TankerShipping #CargoTanks #TankCleaning #ReverseOsmosis #Desalination #Maritime #MarineEngineering #Shipowners #PAndI
