Tricks of the Bunker Trade: Precautions against Cappuccino Bunkers

The Cappuccino Effect, the frothing/bubbling effect caused by compressed air blown through the delivery hose. The aerated bunkers when sounded will give the impression that the fuel is delivered as ordered, when in fact when the entrapped air in suspension settles out of the fuel oil the oil level drops and a short fall is discovered. In large bunker deliveries this could be considerable with huge financial implications.

Cappuccino bunkers were discussed in general in an earlier Tricks of the Bunker Trade, and this article discusses precautions you can take against cappuccino bunkers.

Before Fuel Transfer

At the time of opening gauge fuel oil should be observed from ullage hatches for any foam on the surface of the bunkers. Foam may also be detected on the ullage tape. If there is no foam then the oil level on the tape should appear distinct with no entrained bubbles.

If by observation of the tape and the surface of the fuel you suspect entrained air then obtain a sample of the fuel by lowering a weighted bottle into the tank. Pour the sample into a clean glass jar and observe carefully for signs of foam or bubbles.

If these observations show entrained air the Chief Engineer should not allow the bunkering to start and notify the owners / charterers immediately. The barge Master should be issued with a letter of protest and a copy sent to the ship's agent.

If the barge Master decides to disconnect from the ship and go to another location then the agent should immediately inform the port authority and try to establish where the barge has gone. All relevant times and facts should be recorded in the deck log book.

During Fuel Transfer

If the Chief Engineer has not observed any entrained air during the initial barge survey it is still possible that air can be introduced to the barge tanks or the delivery line during the pumping period.

The Singapore Bunkering Procedure SS 600 prohibits the use of compressed air from bottles or compressors during the pumping period or during stripping and line clearing. It should be confirmed with the barge Master that he will follow this procedure (Reference SS600 paragraphs 1.12.10/11/12/13).

Stripping of barge tanks can also introduce air and stripping should only be performed at the end of the delivery for a short period of time. The barge Master must agree to inform the Chief Engineer when he intends to start stripping and when it has been completed.

Another method by which the air can be introduced into the system is by crack opening the suction valve of an empty bunker tank while pumping from other tanks. Ship's crew and surveyor need to be alert during bunkering and check for the following signs:

• Bunker hose jerking or whipping around.
• Gurgling sound when standing in vicinity of bunker manifold.
• Fluctuations of pressure indication on manifold pressure gauge.
• Unusual noises from the bunker barge

After Fuel Transfer

It is also possible to introduce air into the delivery line during blowing through at high pressure. Therefore it is imperative that the barge informs the ship before and after blowing through is completed so that the ship crew can be extra vigilant during this period.

The ship's bunker manifold valve should be checked shut before gauging of the vessel's tanks.

Key Notes

• Look out for any signs of foam on the surface of the fuel or excessive bubbles on the sounding tape.
• Bunker hose jerking or whipping around
• Gurgling sound when standing in vicinity of bunker manifold.
• Fluctuations of pressure indication on manifold pressure gauge. Unusual noises from the bunker barge
• Remember whenever in doubt or have concerns always issue a letter of protest

Identifying the Cappuccino Effect

Kaivan H. Chinoy is the Founder and Principal Marine Surveyor of AVA Marine Group, owners of Petro Inspect and The Bunker Detectives.