Thief Hatch X-Ring Seal for Pressure Vessel Leakage
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Solution Overview
Problem
Conventional thief hatches in pressure vessel systems are prone to premature leakage due to the natural resistance of pressure within the vessel, debris collection, and deterioration of face seals, leading to potential fugitive emissions.
Innovation Solution
The proposed thief hatch design incorporates an annular seal flange with a tapered inner surface and an X-ring seal assembly, which provides a reliable sealing mechanism by maintaining contact through temperature variations and minimizing frictional drag, while also incorporating a weather cap with a breathable gasket to prevent debris entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional face seal is used in the thief hatch, then the structure is simple, but the seal deteriorates over time leading to premature leakage
Solution Approach 1:
The patent changes the sealing mechanism from a face seal to an X-ring seal that relies on friction parameters. The X-ring seal maintains sealing through controlled frictional drag rather than direct face contact, preventing the deterioration issues of conventional face seals and extending service life while maintaining reliability.
Solution Approach 2:
The patent replaces the mechanical face seal system with an X-ring seal system that uses friction-based sealing. This substitution eliminates the wear and deterioration problems of face seals by using a different mechanical principle where the seal engages through frictional drag on the tapered surface.
2Reliability
If a seal assembly with high sealing force is used, then leakage is prevented, but frictional drag increases making actuation difficult
Solution Approach 1:
The patent optimizes the friction parameters of the X-ring seal to achieve a balance where sufficient sealing force is maintained while keeping frictional drag within acceptable limits for easy actuation. The tapered surface geometry is designed to provide the right amount of frictional engagement.
Solution Approach 2:
The patent uses a tapered (conical) surface geometry instead of a flat surface. This curved geometry allows the X-ring seal to engage at an angle, providing effective sealing while reducing the frictional drag compared to a flat face seal, thereby easing actuation.
3Ease of operation
If the seal surface is made smooth to reduce friction, then actuation is easier, but debris can more easily compromise the seal
Solution Approach 1:
The tapered surface geometry provides a self-cleaning effect where the angled surface helps shed debris rather than allowing it to accumulate. This maintains sealing reliability while keeping frictional drag low enough for easy actuation, resolving the contradiction between smooth surfaces and debris resistance.
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
This design effectively prevents premature leakage by maintaining a seal until a predefined threshold pressure is reached, reduces frictional drag for efficient actuation, and prevents debris from entering the internal chamber, thus ensuring reliable operation and minimizing fugitive emissions.
Implementation Method 1
a biasing element coupled to the piston and configured to apply a biasing force against the piston to bias the piston towards a first position
Implementation Method 2
The tapered inner surface of the seal flange minimizes frictional drag on the X-ring seal
Data Source
AI summary
A thief hatch for a pressure vessel system including an annular seal flange attachable to an opening of a pressure vessel of the pressure vessel system, a piston coupled to the seal flange, an annular seal assembly located between an outer surface of the piston and an inner surface of the seal flange, and a biasing element coupled to the piston and configured to apply a biasing force against the piston to bias the piston towards a first position corresponding to a closed configuration of the thief hatch.