1. Safety Preparation & Isolation
- Drain all fuel and transfer to approved containers.
- Close and isolate valves and connected pipelines.
- Ventilate until flammable vapor, oxygen, and toxic gas levels are safe.
- Wear antistatic clothing, chemical‑resistant gloves, eye protection, and respiratory protection.
- Keep open flames, sparks, and non‑explosion‑proof equipment away from the work area.
2. Sludge Removal & Mechanical Cleaning
- Remove remaining sludge, water, and sediment from the bottom.
- Use non‑sparking tools such as copper scrapers or plastic shovels to avoid ignition risk.
- For heavy deposits, use high‑pressure water washing or steam cleaning.
- Loosen oil film, rust, and sludge from shell, roof, and bottom plate.
- Collect and dispose of wastewater and oily residues per local environmental regulations.
3. Chemical Cleaning & Rust Treatment
- Apply diesel‑compatible alkaline cleaner to remove grease.
- Follow with mild acid or rust remover suitable for carbon steel.
- Control acid cleaning to avoid excessive corrosion of the tank wall.
- Rinse repeatedly with clean water until discharge is clear and neutral.
- Handle all cleaning chemicals and rinse water as hazardous waste where required.
4. Drying, Inspection & Recommissioning
- Dry the tank interior thoroughly using clean air, nitrogen purging, or warm air drying.
- Residual moisture can cause rapid rusting in a recycled carbon steel tank.
- Inspect for corrosion, pitting, weld defects, coating damage, and loose fittings.
- Return to diesel storage service only after passing visual inspection, thickness checks, and leak testing.