Maintenance

Tank Bottom Inspection and Cleaning Verification: When Corrosion Hides Under Sediment

Storage tanks store more than crude. They store water, chemicals, sediment and corrosion products in layers. The tank bottom is the first surface exposed to those layers and the last surface most operators inspect. A bottom inspection after cleaning is the moment to measure remaining metal, note pitting patterns and decide whether the tank can return to service without repair.

Cleaning and inspection methods

Internal inspections usually require the tank to be cleaned, ventilated and gas tested before anyone enters. Once inside, the inspector measures remaining bottom thickness, checks for pitting or weld corrosion and records the findings with locations referenced to fixed tank coordinates. Those coordinates become the comparison for future inspections.

Corrosion under deposits

Microbiologically influenced corrosion and under-deposit corrosion can attack the bottom while the rest of the shell looks clean. The inspector should note deposit type, color and adhesion, because those clues help the corrosion engineer choose the next inspection method or coating repair.

Documentation and the field ticket

OpsFlo can store tank inspection reports and cleaning verification forms as structured records that include the tank ID, inspection method, findings and return-to-service decision. When a downstream inspector or environmental auditor asks for tank condition history, the operator can show the trend instead of a single dated report.

Operators who tag a tank after cleaning show that the unit is not returned to service until the inspection is complete.

Keeping those records in one system makes https://opsflo.app/ workflows easier to search after an audit, with tank inspection reports and cleaning verification forms attached.

Sources and further reading

• API STD 653: Tank inspection
• API RP 571: Damage mechanisms
• eCFR 49 CFR 195.579: Integrity management
• EPA SPCC planning