In steam boiler houses, storage tanks play a critical role in ensuring a consistent and reliable supply of feed water and fuel—typically Light Diesel Oil (LDO). These tanks are engineered to safely store and condition the necessary fluids that feed the boiler system, maintaining optimal boiler performance and safety.
Choosing the right material of construction (MOC)—either Mild Steel (MS) or Stainless Steel (SS)—is essential to ensure durability, corrosion resistance, and compliance with safety standards.
1. Applications of Storage Tanks in Boiler Houses
An air receiver tank is a pressurized vessel used to store compressed air before it is used in a system. In a steam boiler house, compressed air is critical for various applications such as:
1.1 Feed Water Storage Tanks
Feed water storage tanks, often referred to as Hotwells or Deaerator Tanks, are used to store treated water before it enters the steam boiler. They:
- Provide a buffer to handle variable water demand
- Help in deaeration (removal of dissolved oxygen to prevent corrosion)
- Store hot water to reduce thermal shock in the boiler
1.2 LDO Storage Tanks
LDO tanks store Light Diesel Oil, which is used as a fuel for the boiler. Their purpose includes:
- Ensuring uninterrupted fuel supply to burners
- Acting as a safety buffer against supply chain delays
- Allowing safe handling and transfer of fuel to the boiler
2. Materials of Construction (MOC): MS vs. SS
| Corrosion Resistance | Moderate; prone to rust | Excellent; highly corrosion-resistant |
| Cost | Lower | Higher |
| Weldability | Good | Good |
| Maintenance | Requires coatings and regular inspection | Low maintenance |
| Durability | Moderate, depends on environment | High |
| Temperature Tolerance | Good for standard conditions | Excellent |
3. Material Selection Based on Application
3.1 For LDO Storage Tanks
- Recommended MOC: Mild Steel (MS)
- LDO is not highly corrosive, making MS a cost-effective option.
- Proper surface coatings (epoxy or bitumen) can prevent internal corrosion.
- Tanks are typically above ground and monitored regularly.
- Must follow petroleum storage regulations.
- Venting, earthing, and bund walls are required for fire safety.
Why :
Special Considerations :
3.2 For Feed Water Tanks
- Recommended MOC: Stainless Steel (SS)
- Feed water contains oxygen and sometimes chemicals that accelerate corrosion.
- SS offers long-term corrosion resistance, especially at elevated temperatures.
- Improves water purity—important in high-pressure boilers.
- Alternative : MS with internal rubber lining or epoxy coating can be used for budget-conscious projects, but this requires ongoing inspection and maintenance.
Why :
4. Selection Criteria for Storage Tanks
| Fluid Type | Corrosiveness, temperature, chemical reactivity |
| Storage Capacity | Based on boiler size, operating hours, and refill cycles |
| Temperature & Pressure | High-temp feed water needs stronger MOC |
| Environmental Conditions | Outdoor tanks may need UV-resistant coatings or insulation |
| Budget Constraints | MS is cheaper, but SS is cost-effective long-term |
| Maintenance Strategy | SS reduces maintenance needs; MS needs regular upkeep |
| Regulatory Compliance | Especially for fuel tanks – must meet fire and safety norms |
5. Typical Design Features
LDO Tanks :
- Flame arrestors, breather valves, bund walls
- Level gauges, overfill alarms, drain valves
- MS, with corrosion-resistant paint inside
Feed Water Tanks :
- Steam sparging for pre-heating
- Level control system
- SS, or MS with high-grade lining
Conclusion
Choosing the appropriate material for storage tanks in a steam boiler house depends on the fluid being stored, operating conditions, and long-term cost implications. While MS is widely used for LDO due to cost-effectiveness, SS is often preferred for feed water storage due to its superior resistance to corrosion and reduced maintenance needs.
A careful assessment of the fluid properties, environmental factors, and regulatory norms ensures a reliable, safe, and efficient boiler operation.