EPSC Learning Sheet

Imploded Storage Tank

Published 3 February 2020

Contributor

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What Happened?

After cleaning with steam a tank was quenched with cold water to shorten the cooling time (not normal practice). The tank vent was not calculated for the vacuum resulting from this rapid quenching operation, resulting in a collapsed tank (without liquid release).

A larger vent size was installed after the incident

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Aspects:

Atmospheric storage tanks are not designed to withstand external pressure on the tank wall. A pressure as low as 20 mbar below atmospheric pressure can cause tank damage

The force on the wall can be high even at low pressure as the tank wall surface area is very large: Force = Area x delta P

Consider all scenarios resulting in pressures below atmospheric and make sure vent sizes are adequately designed for these, including abnormal operations

Make sure vents and safety devices remain operable: fouling bird nests, plastic bags, have all caused tank implosions

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