Belzona Repair of Leakage on a Diesel Fuel Storage Tank

KHIA ID: 10214
Industry: Oil & Gas (OILG)
Application: TCC-Tanks and Chemical Containment Areas (TCC)
Substrate: Carbon steel
Customer Location: Mount Maunganui, New Zealand
Application Date: February 2026
Products: Belzona 1161 (Super UW-Metal),Belzona 9611 (ES-Metal)
Problem: The customer identified a small leak originating from behind an existing doubler plate that had been installed decades ago, with no records available. The area in question was approximately 8 m above ground level. When the original plate was removed, a small circular dent was observed with a hairline crack of approximately 1 mm above it. Diesel from the tank was weeping through this crack and beneath the plate.

Original defect after cleaning and degreasing.

The defect area was filled with Belzona 9611 (ES-Metal) as a temporary measure to allow hot-work surface preparation of the surrounding repair area.

Surface preparation of the area including cutting in area for the paint to overlap.

Doubler plate installed with chamfered edges, ready for painting.

Application Situation
With no measures in place to deal with a high-pressure live leak scenario (other than the secondary containment area), a serious leak in this diesel tank would have been extremely time-consuming and could have resulted in hundreds of thousands of dollars in lost fuel and clean-up costs. The Belzona solution was completed in under three hours at a cost of $2,500 NZD.
Application Method
An area 100 mm square was marked out, cleaned, and degreased. The crack was then terminated and sealed with Belzona 9611 (ES-Metal) as a temporary measure required by the customer prior to granting a hot-work permit.

Once a gas sniffer had been used to declare the area gas-free, an MBX tool was used for surface preparation. The area was cleaned and degreased once again, and a new doubler plate was bonded in place using Belzona 1161 (Super UW-Metal).

The repair was held in position with a magnet until cured and was then overcoated with the specified paint system.
Belzona Facts
A leak from the diesel tank would have caused a huge spillage, and without any practical means to seal an active live leak, the client would have been forced to pump out the tank to carry out repairs. With the Belzona solution, the crack was terminated and repaired before it could develop into a major issue.
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