Modular Swivel Stack Sealing for In-Situ Seal Replacement
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Solution Overview
Problem
Existing swivel stacks face challenges in seal maintenance and design due to mechanical wear and high-pressure conditions, particularly the inability to change-out dynamic seals in-situ and meeting seal design criteria for varying diameters, temperatures, and pressures.
Innovation Solution
A swivel stack design featuring a rotary interface composed of annular elements with a radial gap and toroidal chamber, allowing for simplified assembly and seal replacement, with face seal type seal rings and additional isolation seals to manage pressure and rotation, and using steel forgings for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If traditional swivel designs are used with sealed rotary interfaces, then hydraulic integrity is maintained under high pressure, but seal replacement becomes extremely difficult and time-consuming
Solution Approach 1:
The rotary interface is divided into modular components: a stationary part integrated with the swivel body, a rotating part connected to the rotor, and interchangeable seal assemblies. This segmentation allows seals to be replaced by removing and reassembling modular components rather than disassembling the entire swivel, maintaining hydraulic integrity while enabling easy seal replacement.
Solution Approach 2:
The seal assembly is extracted as a separate, removable component from the rotary interface. The seals are housed in accessible seal chambers that can be opened to remove and replace seal assemblies without affecting the main hydraulic structure, thus preserving hydraulic integrity during maintenance operations.
2Adaptability or versatility
If seal diameter, temperature range, or fluid pressure increases, then the swivel handles more demanding applications, but meeting seal design criteria becomes increasingly difficult
Solution Approach 1:
Different seal assemblies with specific properties are designed for different operating conditions. The seal chambers are configured to accommodate various seal types (radial seals, axial seals, face seals) selected based on local requirements for pressure, temperature, and diameter, allowing the swivel to adapt to demanding applications without requiring a completely new design.
Solution Approach 2:
The seal system allows changing critical parameters such as seal diameter, material composition, and sealing mechanism type to match specific operating conditions. By selecting appropriate seal assemblies for different pressure ranges, temperature zones, and diameter requirements, the swivel can handle more demanding applications while keeping the base structure relatively simple.
3Ease of operation
If the swivel allows rotation between incoming and outgoing flow lines, then operational flexibility is improved, but mechanical wear on seals increases
Solution Approach 1:
The rotary interface incorporates dynamic seal designs that accommodate rotation through self-adjusting mechanisms. Face seals with compliant elements and radial seals with compensating features maintain contact pressure during rotation, allowing operational flexibility while reducing mechanical wear through self-regulating contact forces.
Solution Approach 2:
The seal assemblies include self-lubricating features and self-adjusting contact pressure mechanisms that reduce mechanical wear during rotation. The design allows seals to self-regulate their operating conditions, maintaining effective sealing while minimizing wear through inherent friction-reducing properties and automatic pressure compensation.
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
Enhances the ease of seal replacement and maintains hydraulic integrity under high-pressure conditions, improving the reliability and performance of the swivel stack by minimizing mechanical stress on seals and maintaining tightness.
Implementation Method 1
fluid of pressure P to the radial groove the fluid exerting a first force longitudinally inwardly on the outer surface of the outer housing, and a second force longitudinally outwardly on the upper and lower surfaces of the radial groove, the second force having a greater magnitude than the first force so the outer housing deflects outwardly, pushing the upper and lower seals into the upper and lower seal slots
Data Source
Figure 1
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AI summary
A swivel stack for transfer of fluid across a rotary interface around a rotation axis between incoming and outgoing flow-lines, includes a group of lower, upper and central annular elements; the lower, upper and central element each being centered around the axis; the central element positioned between the lower and upper elements; an outer annular element centered around the axis between the lower and upper elements; a toroidal chamber between the central and outer elements; downward and upward facing surfaces of the outer element being adjacent to the upward surface of the lower element and the downward surface of the upper element; the lower element's upward surface and the upper element's downward surface having a first stepped surface and the outer element's upward and downward surfaces have a second stepped surface, such that at least two annular cavities centered around the rotation axis are provided.