Terminal · Storage
Fixed Roof Tank
A vertical steel tank with a cone or dome roof welded to the shell. The simplest atmospheric storage tank.
What it does
Stores liquids with low vapor pressure such as heavy crude, water or diesel. A pressure vacuum vent lets it breathe; vapor escapes as the liquid warms during the day and as the tank is filled, so it is not the choice for volatile products.
Basics
| Roof | Cone or dome, fixed to the shell |
| Vent | Free vent or pressure vacuum vent |
| Losses | Standing (breathing) and working (filling) losses |
| Suits | Low vapor pressure liquids |
Common failures
- Stuck pressure vacuum vent that overpressures or collapses the tank during filling or emptying
Troubleshooting
- Symptom
- Roof or shell deformed after a pump out
- Likely cause
- Vacuum vent stuck closed
- What to check
- Inspect and test the vent, check it is sized for the pump rate