High Walled Diked Tanks

Risks involved in storage of flammables in tanks are well known to industry.

This paper will discuss one of the best practices to manage this risk.

Low pressure tanks, per API 650 or API 620 are often used for storing hydrocarbons. When it comes to secondary containment, following options are available.

1. Regular common diking around multiple tanks
2. Sloping with a remote impoundment
3. Double walled tanks
4. 4. High walled dikes.

High walled dike design makes use of a concrete wall around the tank going to the same height as tank forming an annular space that is left open at the top. The annular ring space between the dike and tank
wall serves as full spill containment volume for the primary product tank. High walled design stands out as the best practice offering several advantages as listed below.

1. Concrete wall also acts as a fire wall minimizing impact to surrounding property
2. Protecting the tank from surrounding pool fires
3. Reduce need for diked area, separation distance from other assets and hence real estate
4. Reduce surface area from dike and hence lower evaporation rates. Reduced vapor cloud has favorable impact on risk from flammable or toxic chemicals
5. Quick detection of leak
6. Reduced need for the Fire protection foam quantity

A few downsides exist and design team must take those into account.