High-Pressure Seal Assembly With Hoop Ring Against UHMWPE Extrusion
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Solution Overview
Problem
Liquid jet cutting systems face failures due to extrusion of Ultra-High-Molecular-Weight PolyEthylene (UHMWPE) seals past backup rings, leading to leakage issues under high pressures.
Innovation Solution
A seal assembly comprising an annular seal, a backup ring, and a hoop ring with angled surfaces, positioned between the annular seal and the backup ring, which applies radial forces to prevent extrusion by maintaining static equilibrium and reducing the risk of seal extrusion between the hoop ring and the cylinder or plunger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UHMWPE seal with O-ring and backup ring is used to seal the gap between plunger and cylinder, then sealing function is achieved, but extrusion of UHMWPE material past the backup ring occurs under high pressure
Solution Approach 1:
The backup ring is divided into multiple segments or lobes that can independently deform and conform to the plunger surface, providing multiple contact points and distributing the extrusion forces across several regions rather than a single continuous ring
Solution Approach 2:
The backup ring is pre-compressed or pre-positioned against the plunger surface during assembly, creating initial contact and support before high pressure is applied, preventing the seal from being pushed against the backup ring under operating conditions
2Stress or pressure
If a closely fitted backup ring is used to support UHMWPE seal against high pressure, then pressure support is improved, but extrusion between backup ring and plunger occurs
Solution Approach 1:
The backup ring features localized reinforcement zones or varying thickness sections that provide enhanced support precisely where extrusion forces are most concentrated, while maintaining flexibility in other regions to conform to plunger surface variations
Solution Approach 2:
The backup ring incorporates curved or rounded contact surfaces that match the cylindrical geometry of the plunger, distributing contact stresses more evenly and preventing stress concentration points that would lead to extrusion
3Stress or pressure
If a closely fitted backup ring is used to support UHMWPE seal, then pressure support is improved, but extrusion between backup ring and cylinder occurs
Solution Approach 1:
The backup ring is divided into multiple segments or lobes that can independently deform and conform to the plunger surface, providing multiple contact points and distributing the extrusion forces across several regions rather than a single continuous ring
Solution Approach 2:
The backup ring is constructed from composite materials combining rigid components for structural support with flexible elements that can deform to accommodate pressure variations and prevent extrusion under high stress conditions
Data Source
AI summary
A seal assembly can include an annular seal having a first end portion and a second end portion. The second end portion can include a first annular face, a first tapered portion, and a radially-inner surface configured to seal an outer surface of a plunger. The seal assembly can include a backup ring having a first end portion having with a second annular face and a second tapered portion, and a second end portion. The seal assembly can include an annular hoop ring positioned between the annular seal and the annular backup ring, the annular hoop ring having a first tapered surface configured to engage the annular seal, and a second tapered surface configured to engage the annular backup ring. An angle between the second tapered surface and the longitudinal axis of the annular hoop ring can be between 50 degrees and 80 degrees.