Design
O-Ring Boss Seal Calculator
Check O-ring boss gland geometry for straight-thread hydraulic and pneumatic port connections.
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Calculator guidance and result interpretation
What this calculator solves
The boss-seal model checks the confined gland formed at a straight-thread fitting shoulder, where port geometry and installation depth control compression.
When to use it
- •SAE-style straight-thread ports
- •Hydraulic tube fittings
- •Pneumatic manifolds and adapters
Input parameters
- Port and fitting geometry
- Boss diameter, spotface, gland depth and relevant machining tolerances.
- O-ring dimensions
- Selected ID, cross-section and size tolerances.
- Pressure and hardness
- Peak pressure, clearance and elastomer hardness used for extrusion screening.
How to read the results
- Confirm squeeze remains within range at both shallow and deep gland limits.
- Check gland fill because boss glands can become highly confined.
- Treat an unqualified extrusion result as a prompt to review port clearance, hardness or back-up support.
Engineering considerations
- Confirm the port standard and fitting geometry; similar threads do not guarantee the same gland.
- Installation damage, lead-in chamfers and thread burrs are not represented by the geometric model.
- Use supplier dimensions for proprietary ports.
Related tools and engineering resources
Frequently asked questions
What is an O-ring boss seal?
It is a static seal at the shoulder of a straight-thread fitting. The thread provides clamping, while the O-ring seals in the machined port gland.
Can matching thread sizes use the same O-ring?
Not always. Port standards can differ in spotface, chamfer and gland dimensions even when the thread designation appears similar.