Split Mechanical Seal Assembly With Externally Energized Secondary Seals
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Solution Overview
Problem
Conventional split mechanical seals face challenges in ensuring proper alignment and sealing due to the expansion of O-rings when compressed, leading to potential buckling and pinching, which results in leakage and misalignment of components during assembly.
Innovation Solution
The introduction of an axially movable spring holder plate that compresses O-rings radially, moving them from an unloaded to a loaded position, ensuring proper alignment and sealing contact between rotary and stationary seal rings without premature loading, thus preventing leakage and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If O-rings are compressed radially during assembly, then sealing contact is achieved, but O-rings expand circumferentially causing buckling and pinching
Solution Approach 1:
The spring holder plate is pre-positioned in an axially outermost position during assembly, allowing O-rings to be installed in an unloaded state without premature radial compression. This preliminary positioning prevents buckling and pinching before the sealing action is initiated
Solution Approach 2:
The spring holder plate is designed to be axially movable, transitioning from an axially outermost position during assembly to an axially innermost position during operation. This dynamic movement allows the system to accommodate O-ring deformation during assembly while achieving proper sealing compression during operation
2Productivity
If split gland assembly is bolted together to facilitate assembly, then assembly speed is improved, but misalignment of sealing components occurs
Solution Approach 1:
The spring holder plate is pre-assembled with the stationary seal ring and O-ring in a preassembly unit before final installation. This preliminary assembly ensures proper alignment and positioning of sealing components is established before the split gland assembly is bolted together, preventing misalignment while maintaining assembly speed
3Reliability
If O-rings are compressed radially inside grooves, then sealing is achieved, but ends protrude and buckle when joined
Solution Approach 1:
The spring holder plate is positioned in advance in an axially outermost position that provides adequate axial space for O-ring installation. This preliminary positioning allows O-rings to be installed in an unloaded state without protruding or buckling, making the joining operation easier while maintaining sealing reliability
Solution Approach 2:
The solution addresses the radial compression problem by introducing axial movement of the spring holder plate. During assembly, the plate is positioned axially outward to prevent radial compression; during operation, it moves axially inward to achieve the necessary radial sealing force, effectively using axial dimension to control radial sealing behavior
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 solution effectively prevents O-ring extrusion and buckling during assembly, ensuring a reliable fluid-tight seal by maintaining O-rings in a radially compressed state, enhancing the sealing performance and reducing leakage in split mechanical seals.
Implementation Method 1
The spring holder plate can be moved axially by tightening selected bolts associated therewith. When moved axially, the spring holder plate contacts and moves the stationary seal ring and the O-ring associated therewith in an axially inboard direction. The stationary seal ring in turn contacts and moves axially inwardly the rotary seal ring, which in turn moves the O-ring associated therewith in the axially inboard direction. The O-rings are thus moved from the unloaded position to a loaded position where the O-rings are compressed in a radial direction.
Data Source
AI summary
A mechanical seal that employs an axially movable spring holder plate that engages a sealing element, such as an O-ring, associated with a stationary seal ring. In turn, the stationary seal ring can have a sealing face that engages with a sealing face of a rotary seal ring. The rotary seal ring can also have a sealing element, such as an O-ring, associated therewith. The O-rings are initially disposed in an unloaded position where they are not radially compressed and hence the ends do not expand circumferentially past the end faces of the holder or gland segments. The spring holder plate can be moved axially by tightening selected bolts associated therewith. When moved axially, the spring holder plate moves the stationary seal ring and the O-ring associated therewith in an axially inboard direction, thus placing the O-rings in a loaded position, where the O-rings are radially compressed.