The level of oil on the tape / bob should be clearly identifiable and the same colour and viscosity as the rest of the oil in the tank.
Soundings can be inflated during opening gauging by pouring diesel oil into the sounding pipe just before gauging.
Another method of inflating the sounding is high pressure compressed air being injected directly into the sounding pipe, pressurizing the pipe and thus causing the level of oil to rise giving a higher reading without even frothing or creating bubbles.
This would be done en-route to the vessel just before delivery.
The reverse is also true - that is the soundings can be deflated during closing gauging by pouring copious amount of paint thinner into the sounding pipe just before gauging.
The thinner washes off the oil level marking on the sounding tape to indicate less oil.
Always check the level of on the sounding tape and if in doubt re-gauge the tank
Remember whenever in doubt or have concerns always issue a letter of protest
(c) 2013 Photos provided by Bunker Detective surveyor network
Kaivan H. Chinoy is the Founder and Principal Marine Surveyor of AVA Marine Group, owners of Petro
Inspect and The Bunker Detectives.