1. Most Waste Fuel Tanks Are Atmospheric Storage Tanks
- Usually designed as atmospheric or low‑pressure storage vessels, not pressure vessels.
- Main function: hold used fuel, oily water, sludge, and contaminated residues at near ambient pressure.
- Shell thickness governed mainly by liquid head, wind load, seismic load, and roof stability.
- Not governed by sustained high internal pressure.
2. Typical Pressure Limits for Atmospheric Tanks
- API 650: atmospheric welded storage tanks generally not exceeding 17.2 kPa gauge.
- Chinese atmospheric tank standards: typical design pressures of 6 kPa or 18 kPa gauge.
- Values are reference ranges only; actual allowable pressure depends on tank design.
- Roof type, venting system, and applicable standard all affect allowable pressure.
3. Low Pressure & Pressure Vessel Waste Fuel Tanks
- API 620: low pressure tank rated up to about 1 MPa gauge.
- ASME Section VIII or similar: pressure vessel with higher maximum allowable working pressure shown on nameplate.
- Transport tanks for flammable liquids may have higher ratings.
- These are specialized designs, not typical for stationary waste fuel storage.
4. Always Verify the Actual Nameplate & Design Data
- Confirm from design documents, nameplate, maximum allowable working pressure, and relief valve settings.
- Check applicable local regulations.
- Never assume a waste fuel tank can withstand significant positive or vacuum pressure.
- Overpressurization during pumping, heating, cleaning, or inerting can deform the roof, rupture welds, or cause catastrophic release.