Guide to the Maintenance and Longevity of Stainless Steel Tanks

Stainless steel tanks, despite their high investment costs, are pieces of equipment that can provide decades of trouble-free service with proper maintenance. Maintaining the ‘passivation’ property of your tanks is vital for food safety, chemical resistance, and operational efficiency.

At ÖNSA Makine, we have summarised the simple but critical maintenance steps you need to follow to ensure that the tanks we manufacture maintain their original performance.

1. Things to Consider When Cleaning, Apart from ‘CIP Chemicals’

The CIP (Clean-in-Place) system automates the internal cleaning of the tank, but the external surface and general condition of the tank require manual inspection.

 Chloride Hazard: The number one enemy of stainless steel is chloride (salt) and hypochlorite (bleach/washing powder)-based cleaners. These substances attack the protective oxide layer (passive layer) of the steel, causing pitting corrosion.

 Rule: When cleaning the tank exterior or gaskets, use chloride-free, neutral pH detergents.

 Avoid Abrasive Cleaning: When cleaning the tank surface, absolutely avoid using metal brushes, steel wool or abrasive powders that could scratch the stainless steel. Scratches are potential corrosion initiation points where dirt and bacteria can accumulate.

 Rinse Thoroughly: After cleaning, immediately rinse the tank surface with plenty of clean water to avoid leaving chemical residues.

2. What is ‘Passivation’ and Why is it Important?

What protects stainless steel from rusting is a thin, invisible layer of chromium oxide (passive layer) that forms naturally on the steel's surface.

 Damage to the Passive Layer: This layer is damaged by factors such as welding, grinding, scratching, or contact with chlorides. The damaged area becomes the most vulnerable point on the tank for corrosion.

 Repassivation (Recommended): For tanks that have undergone new welding or been subjected to heavy chemical cleaning, this protective layer must be professionally re-established. This process is typically performed using nitric acid or special passivation solutions. This significantly extends the tank's lifespan.

3. Mechanical Control and Spare Parts Management

The longevity of the tank depends not only on the steel but also on the moving parts.

 Gaskets (Sealing Elements): All valve, cover, and manhole gaskets should be checked periodically. Cracking or hardening of gaskets leads to leaks and hygiene risks. In the food industry, ensure that seals are made of food-grade materials such as EPDM or silicone.

 Agitator Shaft and Reducer Inspection: The agitator shaft bearing, reducer, and motor connections should be regularly inspected for excessive vibration or noise. Leaks must be addressed immediately upon detection.

 Level and Temperature Sensors: Ensure these sensors are functioning correctly and have not been damaged during cleaning. Accurate measurements guarantee the quality of your process.

 ÖNSA Machine Spare Parts Support: You can quickly obtain critical spare parts such as gaskets, valves, and sensors through our e-commerce site.

Maintaining your tanks is not a cost, but the most important investment in your ability to produce with zero defects.

Publication Date: 25.11.2025