Storage Tank Cannot Be Used Normally After Long-Term Idle—Causes and Solutions

Long-term idle storage tanks—whether used for cryogenic liquids, chemicals, LPG, or industrial gases—may experience performance degradation or functional failure when reactivated. Understanding the causes and implementing proper recovery measures are essential to ensure safe and reliable operation.

1. Causes of Functional Failure After Long-Term Idle

Internal Corrosion or Rusting
Without regular use, residual moisture, impurities, or condensation can corrode the inner wall, affecting strength and sealing performance.

Valve and Pipeline Seizure
Valves, pumps, and actuators can freeze, seize, or stiffen due to lack of lubrication, oxidation, or internal deposits.

Insulation Performance Degradation
For cryogenic tanks, vacuum loss, insulation moisture absorption, or settling of insulation materials may cause high heat ingress or abnormal boil-off.

Seal and Gasket Aging
Rubber seals and gaskets become brittle or deformed over time, leading to leakage, poor sealing, or pressure loss.

Instrumentation Failure
Liquid level gauges, pressure transmitters, temperature sensors, and safety valves may drift, jam, or lose accuracy after long-term inactivity.

Contaminant Accumulation
Dust, rust flakes, hydrocarbons, or other contaminants may accumulate inside the vessel or piping.

2. Recommended Handling Measures

Comprehensive Internal and External Inspection

Check for corrosion, cracks, deformation, or coating damage.

Inspect saddle supports, anchor bolts, and foundation settlement.

Valve and Pipeline Maintenance

Clean and lubricate all valves, replace stiff or damaged seals.

Perform pressure testing to verify integrity.

Restoration of Insulation or Vacuum

For cryogenic tanks, restore vacuum level if degraded.

Replace wet or compromised insulation materials when necessary.

Cleaning and Drying

Conduct internal cleaning to remove rust, dust, hydrocarbons, or residues.

Dry the tank with nitrogen or hot air to eliminate moisture.

Instrumentation Calibration and Replacement

Calibrate pressure and level sensors.

Replace non-responsive gauges or stuck safety valves.

Leak Testing Before Recommissioning

Conduct air-tightness and pressure tests to confirm seals and weld integrity.

For cryogenic service, perform pre-cooling tests before liquid filling.

3. Preventive Strategies for Future Idle Periods

Keep tanks clean and dry before shutting down.

Purge with dry nitrogen to reduce oxidation and moisture absorption.

Periodically rotate and actuate valves to prevent seizing.

Maintain minimum pressure/vacuum levels for cryogenic vessels.

Schedule periodic inspections even during storage periods.

Conclusion
Long-term idle storage tanks can face issues such as corrosion, valve seizure, insulation degradation, and instrumentation failure. Proper inspection, cleaning, maintenance, vacuum restoration, and leak testing are essential before reactivation. Implementing preventive measures during idle periods can significantly improve tank reliability and extend service life.

References

API 650 – Welded Tanks for Oil Storage.

API 620 – Design and Construction of Large, Welded, Low-Pressure Storage Tanks.

EN 14620 – Design and Manufacture of Site Built, Vertical, Cylindrical, Flat-Bottomed Cryogenic Vessels.

ASME Boiler and Pressure Vessel Code, Section VIII – Pressure Vessels.

NFPA 55 – Compressed Gases and Cryogenic Fluids Code.