Safety Valve Piston Seal Assembly for Back Pressure Load Diversion
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Solution Overview
Problem
Safety valve pistons in hydrocarbon well applications often experience seal extrusion and pressure leaks due to back pressures, which compromise the reliability of the seal assembly and the operation of safety valves.
Innovation Solution
A safety valve piston seal assembly is designed with a load ring and spacers to divert the load path to the piston instead of the seal assembly, using a metal spring energized (MSE) seal and V-ring configuration that prevents reverse loading, thereby enhancing the sealing reliability by directing potential loading to the piston rather than the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seal assembly is used to seal between the piston and surrounding surface, then sealing function is provided, but seal extrusion and pressure leaks occur under back pressure conditions
Solution Approach 1:
A load ring is introduced as an intermediary component between the piston and the seal assembly. The load ring receives back pressure loads and redirects them to the piston body, preventing direct transmission of harmful back pressure to the seal assembly. This mediator structure protects the seal from extrusion while maintaining sealing functionality.
Solution Approach 2:
The seal assembly is segmented into distinct functional components: sealing elements (V-rings, U-rings) for creating seals, and a load ring for managing pressure loads. This segmentation allows the load ring to handle back pressure separately from the seal elements, preventing seal extrusion while maintaining sealing integrity.
2Reliability
If the seal assembly directly withstands back pressure, then sealing is maintained, but detrimental loading causes seal extrusion and failure
Solution Approach 1:
The load ring serves as a structural intermediary that intercepts back pressure loads before they reach the seal assembly. By redirecting these loads to the piston body through its robust structure, the load ring protects the seal assembly from detrimental loading that would cause extrusion and failure.
Solution Approach 2:
Instead of allowing the seal assembly to directly withstand back pressure loads, the design inverts the load path by using the load ring to redirect forces. The load ring engages the piston body to bear the back pressure, effectively reversing the conventional load transmission path and protecting the seals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces detrimental loading on the MSE seal, preventing seal extrusion and pressure leaks, and ensures reliable operation of safety valves even under back pressure conditions, enhancing the bidirectional pressure sealing capability.
Implementation Method 1
The V-ring and U-ring are arranged to provide a bidirectional pressure seal around the piston
Implementation Method 2
metal spring energized (MSE) seal
Data Source
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AI summary
A technique facilitates improved sealing with respect to safety valve pistons so as to improve reliable safety valve operation. According to an embodiment, a safety valve piston seal assembly is positioned about a safety valve piston and comprises components which divert a load path to the safety valve piston rather than to susceptible components of the seal assembly. For example, the seal assembly may comprise a load ring and spacers to energize a V-ring when pressure is applied to a metal spring energized (MSE) seal. However, the components are arranged so the load path is diverted to the safety valve piston when pressure occurs behind the V-ring instead of allowing the loading to act against the MSE seal.