Tank floor failure in 2-Ethylhexlynitrate service.

The tank failure occurred due to internal corrosion of the floor and lower wall resulting in a hole of approximately 10mm.

The floor and wall of the tank was uncoated carbon steel and had been inspected in the last 10 years. No pH checks were carried out as part of this inspection. The inspection concluded that the tank was in good condition.

The tank had no water draw sump but a downturned suction nozzle.

Following the failure, inspection revealed that a small amount of moisture had accumulated on the tank floor due to normal tank inbreathing/outbreathing. It is likely that in the presence of water the product can hydrolyse to nitric acid, thus causing the corrosion.

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