A2Z was contracted by International
Steel Group to clean a three million gallon #6 fuel oil tank.
The tank needed to be gas-free in order to expedite needed repairs
that included welding and burning. The tank contained 200 thousand
gallons of #6 fuel oil that had to be transferred before cleaning.
The job was contracted for a fixed price to be completed in eight
weeks. If the job took longer, A2Z had to absorb the additional
cost. If the job finished early, there would be a bonus paid.
Number six oil is very dense
oil that doesn't flow very well. A six man crew containing
operators and technicians arrived to transfer the oil using vacuum
trucks and vacuum trailers on site. The transfer operation was
completed in two weeks.
Once the bulk of the #6 fuel
oil was vacated, there was a thick residue of #6 fuel oil stuck
to the walls and floor of the tank. This residue was too thick
to pump. Number two oil was used to cut, or dilute the #6 fuel
oil. It was sprayed and worked with squeegees very methodically
in order to cut the oil for removal. Two five man crews worked
around the clock, on 12 hour shifts to expedite the removal of
the oil. It took two weeks to remove enough oil to allow surface
cleaning of the tank.
During the washing stage, a 3500
PSI hot water pressure washer was used to clean the tank. The
complete floor and 8" of the walls needed to be clean enough
to pass a gas-free test. The oxygen level must be 20.9 or higher
and the LEL (Lower Explosive Limit) read less than 10%. To achieve
this level hot water was used to wash off the oil. The two five
man crews worked around the clock washing and removing the rinsate.
The rinsate was taken to an oil recycling company on the grounds
of International Steel Group for recycling. No disposal left
the site.
A Marine Chemist was brought
in to inspect the tank five weeks after the job started. A certificate
was given as the tank passed inspection on the first test. The
job was completed three weeks early.
