How to Select RO Membrane Housing Materials — FRP vs. Stainless Steel| Insights by AQUALITEK
Learn how to choose the right reverse osmosis (RO) membrane housing material — FRP or stainless steel — with a complete comparison of working conditions, corrosion resistance, cost, and application suitability.
- Choosing the Right RO Pressure Vessel Material
- FRP Membrane Housing (Fiberglass Reinforced Plastic)
- Key Features
- Best Application Scenarios
- ✅Advantages
- ❌Disadvantages
- Stainless Steel Membrane Housing (SS304 / SS316L)
- Key Features
- Best Applications
- ✅Advantages
- ❌Disadvantages
- FRP vs Stainless Steel — Direct Comparison
- Which Should You Choose?
- Choose FRP if:
- Choose Stainless Steel if:
- Conclusion
Choosing the Right RO Pressure Vessel Material
The membrane housing (pressure vessel) is a critical component in industrial reverse osmosis systems. It must withstand:
✅ High operating pressure
✅ Chemical and corrosion exposure
✅ Long-term mechanical stress
✅ Water quality and temperature variations
The most common materials are:
1️⃣ FRP (Fiberglass Reinforced Plastic)
2️⃣ Stainless Steel (SS304 / SS316L)
Each material offers unique performance benefits depending on the application environment.
FRP Membrane Housing (Fiberglass Reinforced Plastic)
Key Features
|
Factor |
Performance |
|
Pressure Tolerance |
Medium to high (up to 1200 psi) |
|
Corrosion Resistance |
Excellent (no rusting) |
|
Weight |
Very lightweight |
|
Cost |
Low |
Best Application Scenarios
|
Condition |
Suitability |
|
Brackish water RO |
✅ Strongly recommended |
|
Seawater RO |
✅ With special liners |
|
Outdoor environment |
✅ UV-resistant |
|
High-chloride water |
✅ Non-metallic advantage |
|
Limited budget |
✅ Cost-effective |
✅Advantages
✔ Highly corrosion-resistant
✔ Low total cost of ownership
✔ Easy to install and maintain
❌Disadvantages
✖ Heat tolerance lower than stainless steel (≤50–55°C recommended)
✖ Mechanical rigidity lower than metal
✖ Not suitable for extremely high pressure > 1200 psi
Stainless Steel Membrane Housing (SS304 / SS316L)
Key Features
|
Factor |
Performance |
|
Pressure Tolerance |
Very high |
|
Mechanical Strength |
Excellent |
|
Chemical Resistance |
Medium–High (SS316L better) |
|
Surface Hygiene |
Excellent (smooth interior) |
Best Applications
|
Condition |
Suitability |
|
High-temperature water |
✅ Better heat resistance |
|
Pharmaceutical / Food-grade |
✅ GMP hygienic design |
|
High-pressure applications |
✅ Strong structural integrity |
|
Cleanroom / indoor systems |
✅ Aesthetic+sanitary benefits |
✅Advantages
✔ High structural strength & safety factor
✔ Easy to clean and sanitize
✔ SS316L resists chloride better than SS304
❌Disadvantages
✖ Higher cost
✖ Risk of chloride corrosion (especially in seawater)
✖ Heavy — requires complex installation
Chloride Stress Corrosion Threshold:
•SS304: < 200 ppm chloride preferred
•SS316L: < 600 ppm chloride preferred
FRP vs Stainless Steel — Direct Comparison
|
Attribute |
FRP |
Stainless Steel |
|
Pressure Resistance |
Medium–High |
Very High |
|
Chloride Resistance |
Excellent |
Limited (risk of corrosion) |
|
Temperature Resistance |
Lower |
Higher |
|
Cost |
Low |
High |
|
Weight |
Light |
Heavy |
|
Surface Cleanliness |
Medium |
Excellent |
|
Preferred Industries |
Municipal & Industrial RO |
Pharmaceuticals, Food, Power |
|
Seawater Suitability |
Good (with liner) |
Risky unless duplex alloys |
Which Should You Choose?
Choose FRP if:
✔ High chloride or corrosive media
✔ Outdoor installation or seawater plant
✔ Budget is a priority
✔ Standard industrial RO application
Choose Stainless Steel if:
✔ High pressure or high temperature
✔ Ultra-hygienic requirements (pharma/food)
✔ Need frequent chemical cleaning with heat
✔ Indoor critical process systems
Conclusion
There is no single perfect choice — the right membrane housing material must match:
•Water chemistry
•Pressure & temperature levels
•Regulatory & hygiene requirements
•Total lifecycle cost
In most industrial RO systems → FRP is the mainstream choice
In high-purity or high-pressure environments → SS316L provides better safety & performance
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