Sealing Array With Backup Rings for High Temperature Applications
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Solution Overview
Problem
Conventional sealing arrays in high temperature applications, such as steam environments, face limitations due to O-ring material extrusion and bonding with V-ring seals, leading to reduced sealing capability and shortened useful life.
Innovation Solution
A sealing array configuration featuring a pair of oppositely disposed backup rings with concave surfaces and rigid cap rings with convex surfaces, along with an energizing element, which forms extrusion gaps and prevents excessive O-ring extrusion and material interaction, using materials like flexible graphite and stainless steel for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single O-ring is used in a gland groove, then the sealing structure is simple, but the O-ring extrudes into the clearance gap and its useful life is limited
Solution Approach 1:
The sealing system is divided into multiple independent components: a centrally disposed O-ring seal, V-ring backup members on either side, and cap rings at the ends. Each component performs a specific function - the O-ring provides the primary seal, the V-rings prevent extrusion into the clearance gap, and the cap rings contain the sealing array. This segmentation allows each element to be optimized for its specific role, improving overall reliability while managing complexity.
2Reliability
If conventional sealing arrays with V-rings are used, then O-ring extrusion is prevented, but the O-ring material diffuses into or bonds with the V-ring material at high temperatures, reducing sealing capability
Solution Approach 1:
Cap rings are introduced as intermediary elements that position the sealing array and maintain the clearance gap between the O-ring and the inner cooperating part. By controlling the positioning and spacing through these cap rings, the design prevents excessive compression that would cause material diffusion and bonding, thereby extending the useful life of the sealing array in high temperature applications.
Solution Approach 2:
The design carefully controls the compression parameter of the O-ring by positioning it between cap rings that maintain a specific clearance gap. This controlled compression prevents the O-ring from being overly compressed against the V-rings, reducing the tendency for material diffusion and bonding at high temperatures, thus extending the sealing array's service life.
3Reliability
If the O-ring is compressed to provide contact stress, then sealing is improved, but the O-ring extrudes into the clearance gap between cooperating parts
Solution Approach 1:
V-ring backup members are positioned on either side of the centrally disposed O-ring seal to prevent extrusion into the clearance gap before extrusion can occur. These V-rings act as preliminary protective elements that constrain the O-ring laterally, allowing the O-ring to be compressed for sealing contact stress without risking extrusion and loss of cross-sectional integrity.
Data Source
AI summary
A sealing array for positioning in an annular space between tubular members to provide a seal therebetween. The sealing array includes a pair of oppositely disposed backup rings, each defining a primary outer seal member of the sealing array. A pair of rigid cap rings is disposed between the backup rings. Each cap ring has a substantially planar surface and an oppositely disposed surface that engages one of the backup rings to energize the backup rings upon the application of sufficient pressure. The cap rings are sized to form controlled extrusion gaps with both tubular members. An energizing element is disposed between the planar surfaces of the cap rings. The energizing element engages a planar surface of at least one of the cap rings and seals the extrusion gaps associated with the engaged cap ring upon the application of sufficient pressure.