DP Fuel Tank Services - tank cleaning, power station, black oil, large tanks, UK

DP Fuel Tank Services has just completed a major contract to clean four huge fuel tanks at Slough Heat & Power, now owned by Scottish and Southern Energy, preparatory to the tanks being demolished by main contractor J Mould (Reading).

All the tanks and pipes had to be de-gassed, drained of residual oil and thoroughly cleaned, to ensure they were safe to work on by the demolition crew and the metal was suitable to be sent for recycling.

The four tanks comprised two very large 2,000,000ltr (13m diameter by 15m high) tanks, one large 360,000ltr (6m by 13m) tank and one medium 100,000ltr (3m by 15m) tank.

One of the very large tanks and the medium tank were comparatively easy to work on, as the medium had been taken out of use and water filled some time before, and the very large, while it had contained heavy oil, had been used for light gasoil (red diesel) for some time.

“The real challenge,” says DP Fuel Tank Service site supervisor Garry Reeve, “was the two heavy oil tanks, where we had to get creative.”

When heavy oil gets cold it solidifies to the consistency of toffee, so steam powered heating elements were built into the tank at about half a metre from the floor, which kept the oil flowing when the tanks were being used.

Unfortunately, when the tanks were drained down as much as they could be, the oil level was left just below the heating elements and, after being left for some while, could not be re-liquefied.

“While we were helped by a spell of warm weather, the oil was still too solid to pump, so we decided to cold cut the elements’ supports to lower the elements into the remaining oil.

“We also pumped the remaining gasoil from the other tanks into the heavy oil to help thin it down.”

The tactic worked, and DP Fuel Tank Services were able to pump most of the oil into a specialist tanker for safe disposal. The rest was clean by hand.

“The client was really pleased at both the successful method used and the result achieved by the teamwork of our two companies,” added Dave Leathers, senior surveyor for J Mould (Reading). “The company has now expressed a wish for us to carry out more of the same.”

The demolition is a consequence of the station – which supplies electricity, heat and steam to local businesses – changing its fuel from coal and oil to biomass.

The station, which was built by Slough Estates, now SEGRO, in the 1920s is now owned by Scottish and Southern Energy.