A chemical processing plant handling highly corrosive media faced frequent failures in pump seal components. After repeated maintenance issues and unexpected downtime, the plant transitioned from reaction bonded silicon carbide (RB-SiC) to pressureless sintered silicon carbide (SSiC).

The result was a significant improvement in service life, stability, and overall operational efficiency.

Background

The plant operates in a continuous production environment involving:

• Concentrated sulfuric acid (H₂SO₄)
• Elevated temperatures (~90–120°C)
• High-speed rotating pump systems

Mechanical seals were identified as a critical failure point, directly affecting system reliability.

The Problem with RB-SiC Components

Initially, the plant used RB-SiC seal rings due to their lower cost. However, several issues were observed:

1. Corrosion in Acid Environment

RB-SiC contains free silicon, which is vulnerable to chemical attack.

Result:

• Gradual material degradation
• Surface roughening
• Reduced sealing performance

2. Reduced Service Life

Seal components required replacement every 2–3 months, leading to:

• Frequent maintenance
• Increased downtime
• Higher operational costs

3. Unstable Performance

Inconsistent material behavior caused:

• Leakage risks
• Reduced reliability in continuous operation

Solution: Switching to SSiC

To address these issues, the plant upgraded to pressureless sintered silicon carbide (SSiC) seal components.

Why SSiC?

• No free silicon phase
• High purity (SiC ≥ 98.5%)
• Near-zero porosity
• Superior corrosion resistance

Results After Implementation

After switching to SSiC, the plant observed immediate improvements:

1. Extended Service Life

• Seal life increased from 2–3 months → 12+ months
• Reduced replacement frequency

2. Improved Corrosion Resistance

• No visible chemical degradation
• Stable surface condition over time

3. Reduced Maintenance Costs

• Fewer shutdowns
• Lower spare parts consumption

4. Enhanced Operational Stability

• Consistent sealing performance
• Reduced leakage risk

Performance Comparison

Key Takeaways

• Material selection directly impacts system reliability
• RB-SiC may be suitable for mild environments, but not for strong acids
• SSiC provides long-term stability in aggressive chemical conditions

Applications Similar to This Case

This upgrade approach is applicable to:

• Chemical pump seal systems
• Acid transfer processes
• Corrosive fluid handling equipment

Conclusion

For chemical plants operating in strong acid environments, switching from RB-SiC to SSiC can significantly improve performance and reduce total cost of ownership.

Although the initial material cost may be higher, the extended service life and reduced downtime make SSiC the more cost-effective solution in the long run.

Looking for Reliable SiC Seal Components?

SSiC seal rings and pump components can be customized for demanding chemical environments.

 Providing application details (media, temperature, operating conditions) allows for optimized material selection and longer service life.