Frequently Asked Questions (FAQ)

What is the Marine Urea Solution solution?

Marine Urea Solution or technically known as AUS40 is 40% Urea Solution used for the purpose of reducing Nitrogen Oxides (NOx) emission from the vessel exhaust. 

What’s the shelf life of the Marine Urea Solution?

The shelf life of 40% Marine Urea solution is around 18 months if stored at between 0 – 25 Degrees Celsius °C or 32 to 77 Degrees Fahrenheit (°F). Below is only an estimated shelf life of 40% Marine Urea Solution based on average storage temperature.

Average Storage Temperature (°C)Average Storage Temperature (°F)Shelf Life (At least)
0-2532 – 7718 months
Less than 30Less than 8612 months
Less than 35Less than 956 months
More than 35More than 95Best to check every batch before use. Marine Urea Solution is unstable at such high temperatures.
However, the storage temperature is not the only factor that affects the shelf life. For more information, please drop us an email at  [email protected]. Hear from you soon.

Why is it important to use the Marine Urea solution to control NOx emission from the marine vessel?

It’s important to reduce Nitrogen Oxides (NOx) emission from the marine vessel as well as vehicle exhaust because it’s known to cause lung cancer.

How can a Marine Urea solution reduce your marine engine’s NOx emissions?

The Marine Urea Solution enters the flue gas steam. The hot exhaust breaks the marine urea solution into various components. Of which, ammonia is the active component that reacts with the nitrogen oxides (NOx) to form harmless nitrogen and water molecules. 

Will the 40% Marine Urea Solution freeze if a vessel always sails in freezing temperatures?

The freezing temperature of the 40% Marine Urea Solution is around 0 degrees Celsius. This may become a problem when the vessel is always sailing in regions with sub-zero temperatures.

But not to worry, vessel designers would have thought about it. They would have designed the vessel to reduce the chances of the Marine Urea Solution freezing in the onboard storage tank. 

To vessel designers, do take note of the shelf life and storage temperature (link to another article for shelf life) for 40% Marine Urea Solution. If you need more information, do feel free to contact us.

Can we choose not to use any Selective Catalytic Reduction (SCR) system to control the marine vessel emission?

The answer is no. Unless your vessel fulfils the conditions set by MARPOL. View MARPOL Regulations.

Why is Marine Urea Solution used for SCR and why is it 40%?

Urea Solution is chosen because it’s non-hazardous (this depends on the country jurisdiction) and relatively safer to handle than other alternatives. 40% is chosen by most marine Selective Catalytic Reduction (SCR) system makers because it’s most efficient. For the same volume of urea solution, 40% will be able to treat more exhaust compared to 30%. This means that the same volume will last you longer

What’s the alternative to Marine Urea Solution (AUS40)?

Ammonia solution is the alternative. It’s highly corrosive and very dangerous to handle. In most countries, special licenses and permits are required to transport, supply and handle ammonia. That’s the reason why Marine Urea Solution (AUS40) is still the preferred and safer choice to control NOx emission.

Why is good quality Marine Urea Solution (AUS40) important?

In a marine Selective Catalytic Reduction (SCR) system, one of the very expensive components is the catalyst. When bad quality Marine Urea Solution (AUS40) is introduced to the SCR System, the impurities will clog up the SCR catalyst and render it less effective and eventually (and rapidly) useless. 

Following may happen:

  • The Marine SCR catalyst will need to be changed before it’s due
  • The clogged Marine SCR catalyst may cause problems to other system components.
  • At the next port call, the vessel would fail the NOx emission test and subject to penalties or delays (depending on the marine/port authorities)

Therefore it’s important to pick reliable Marine Urea Solution (AUS40) suppliers.

Urea Handling

How should urea be stored onboard a ship?

Urea will be stored inside a tank inside the vessel. The tank will be made of compliant material or coating stipulated by ISO 18611. 

What will happen in the case of a spill or someone is splashed with Marine Urea Solution (AUS40)?

  • Always refer to the Marine Urea Solution (AUS40) supplier’s Safety Data Sheet (SDS). 
  • In case of spillage, wipe the area dry and rinse the area with plenty of water.
  • In case someone is splashed with Marine Urea Solution (AUS40), immediately rinse the affected area with water and change out of the wet clothes.

Why does the Marine Urea Solution (AUS40) smell like urine?

A small amount of the urea solution has decomposed into carbon dioxide and ammonia. It’s the ammonia that smells like your urine.

Some urea solution smells really bad, is the concentration higher?

This is a very common misconception. The smell is definitely not an indicator of urea concentration. Everyone’s smell is subjective and highly inaccurate. It’s always better to rely on scientific methods to determine the urea solution concentration. You can refer to the supplier Certificate of Assessment (COA) to find out the marine urea solution concentration.

What’s the freezing point of Marine Urea Solution (AUS40)?

The freezing point of Marine Urea Solution (AUS40) is approximately around 0 (zero) degree Celsius.