Home > Product > Ferrule Fittings > Technical Resources > Single Ferrule vs Double Ferrule
Perfect Engineers, through its advanced fluid control brand PE-LOCK, offers both Single Ferrule and Double Ferrule tube fittings for critical applications across industries. While both provide leak-proof connections, the choice between them depends on pressure, media type, vibration exposure, and reusability needs.
In this technical guide, we compare Single vs Double Ferrule fittings—highlighting their construction, working principles, performance, and ideal use cases—so you can make the right selection for your instrumentation or process system.
| Feature | Single Ferrule Fitting | Double Ferrule Fitting |
|---|---|---|
| Number of Ferrules | One (combined grip & seal) | Two (front ferrule + back ferrule) |
| Sealing Mechanism | Compression of one ferrule against the tube | Front ferrule seals, back ferrule grips |
| Tube Grip Strength | Moderate | High (resists pull-out and vibration) |
| Ease of Assembly | Simple | Slightly more steps, precision assembly |
| Pressure Ratings | Up to ~6,000 PSI | Up to 10,000 PSI or more (depending on size) |
| Reusability | Moderate (can degrade with repeated use) | High (maintains seal after multiple cycles) |
| Vibration Resistance | Moderate | Excellent (prevents tube movement) |
| Applications | General purpose, low to medium pressure | Critical sealing, high-pressure, safety zones |
| Interchangeability | Limited between brands | Common industry standard (PE-LOCK, Swagelok®) |
| Cost | Lower | Slightly higher due to added ferrule |
A single ferrule fitting uses one conical ferrule to simultaneously seal and grip the tube. It’s ideal for general-purpose instrumentation, low-pressure hydraulic lines, and non-critical gas systems.
Pros:
Limitations:
A double ferrule fitting consists of a front ferrule that creates a leak-tight seal and a back ferrule that grips the tube securely. This separation of functions makes it the industry standard for high-pressure, high-purity, and mission-critical applications.
Advantages:
Applications:
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Perfect Engineers offers:
| Tube Size (OD) | Single Ferrule (SS316L) | Double Ferrule (SS316L) |
|---|---|---|
| 1/4″ | ~4,500 PSI | ~6,000 PSI |
| 3/8″ | ~3,500 PSI | ~5,000 PSI |
| 1/2″ | ~3,000 PSI | ~4,800 PSI |
Not always. The body geometry may differ. Always use matching fitting bodies and ferrules.
Yes. PE-LOCK double ferrule fittings are fully interchangeable in form and function.
Limited reusability. They may deform after multiple tightening cycles. Use double ferrule for maintenance-heavy applications.
Single ferrule is cheaper up front, but double ferrule provides better lifecycle performance and safety margin.
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