Valves for Sulphuric Acid (H₂SO₄) Service
Sulphuric acid is one of the most widely used industrial chemicals. Corrosivity varies dramatically with concentration: dilute acid (<50%) is highly aggressive to most metals; concentrated acid (>93%) passivates carbon steel but attacks stainless steels.
Pressure Range
0.5–25 bar (7–360 psi) — process dependent
Temperature
Ambient to 80°C typical; up to 200°C in some processes
Industries
Chemical, Fertiliser, Mining (acid leach)
Key Properties — Sulphuric Acid (H₂SO₄)
- Highly corrosive at dilute concentrations (<50%)
- Carbon steel passivates above 78% concentration
- Stainless steel 316 acceptable up to ~20% at low temperature
- Generates heat on dilution — thermal shock risk
- Strong oxidiser at high concentrations
Material Compatibility — Sulphuric Acid (H₂SO₄)
Ratings are indicative. Actual compatibility depends on concentration, temperature, velocity, and presence of contaminants. Always consult corrosion tables or a materials engineer.
| Material | Rating | Notes |
|---|---|---|
| Carbon Steel (WCB/A105) | Good | Only for >93% concentrated acid at ambient temperature. Not for dilute acid. |
| SS 316L | Fair | Up to ~20% at <25°C. Not recommended above 20% or elevated temperature. |
| Hastelloy C-276 | Excellent | Excellent across all concentrations. Industry standard for dilute H₂SO₄. |
| PTFE-lined | Excellent | PTFE is excellent across all concentrations and temperatures up to 200°C. |
| FRP / PVDF-lined | Good | PVDF and FRP good for <80% concentrations. |
| Ductile Iron | Poor | Not recommended for any concentration. |
| Bronze / Brass | Not Recommended | Severely attacked. Never use copper alloys. |
| Duplex 2205 | Fair | Limited to dilute, cold service only. Verify with corrosion data. |
Recommended Valves
PTFE-lined ball valve
Full bore, zero dead-legs, PTFE lining handles all concentrations
Hastelloy C-276 ball valve
Alloy wetted parts for dilute acid service
PTFE-lined butterfly valve
Cost-effective for large bore, low-pressure dilute acid
Diaphragm valve (PTFE/EPDM)
No stem packing contact with fluid — ideal for leakage-sensitive service
Alloy-body globe valve
Throttling service in corrosive acid streams
Valves to Avoid
Bronze or brass-bodied valves
Standard SS 316 for concentrated acid above 20%
Rubber-lined valves (except EPDM in specific concentrations)
Valves with copper alloy trim
Special Considerations
Applicable Standards
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