Dual-Ring Stuffing Box Structure for High-Pressure Sealing
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Solution Overview
Problem
Traditional stuffing boxes for pumping systems, particularly in hydraulic fracturing, are expensive due to large forging requirements and prone to failures at threaded interfaces, making them difficult to install and maintain.
Innovation Solution
A dual-ring stuffing box configuration using a pressure ring and an adjacent ring, both made from different materials, is flanged into place with fasteners, where the pressure ring houses a face seal and is exposed to high pressure, while the adjacent ring is less expensive and isolated from the pressurized fluid, with a sealing element between the rings and a weep hole configuration to manage fluid exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional stuffing box is used with large forging requirements, then sealing reliability is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The stuffing box is divided into two separate rings: a pressure-containing ring that interfaces with the pressurized fluid end, and an adjacent ring that is not exposed to high pressure. This segmentation allows each component to be manufactured independently with simpler processes, eliminating the need for large complex forges while maintaining sealing reliability through the coordinated design of both rings.
Solution Approach 2:
Different material properties and manufacturing approaches are applied to different parts of the stuffing box. The pressure-containing ring uses materials and manufacturing processes suitable for withstanding high pressure, while the adjacent ring can use less expensive materials and simpler manufacturing. This local differentiation optimizes both reliability where needed and manufacturing simplicity where less critical.
2Strength
If a single-piece stuffing box is used, then structural integrity is improved, but installation and maintenance difficulty increase
Solution Approach 1:
The stuffing box is segmented into two replaceable rings that can be installed and removed independently. This allows for easier installation and maintenance compared to a single-piece design, as components can be replaced without removing the entire stuffing box assembly, while threaded interfaces provide secure attachment that maintains structural integrity during operation.
3Reliability
If expensive materials are used throughout the stuffing box, then durability is improved, but material cost increases
Solution Approach 1:
Expensive, durable materials are applied only where necessary - specifically in the pressure-containing ring that is exposed to high pressure and corrosive fluids. The adjacent ring, which is isolated from the pressurized fluid, can use less expensive materials. This local quality approach ensures durability is improved in critical areas while material costs are reduced overall.
Solution Approach 2:
The pressure-containing ring acts as an intermediary barrier that protects the adjacent ring from exposure to corrosive, high-pressure fluids. This intermediary structure allows the use of expensive corrosion-resistant materials only where they are needed to combat the harsh environment, while less expensive materials can be used in protected areas.
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
Reduces material costs and installation complexity, enhances durability by isolating the less expensive ring from high pressure, and minimizes exposure to corrosive fluids, thereby reducing maintenance and improving operational reliability.
Implementation Method 1
a face seal positioned at an interface of the pressure ring and the fluid end face, the face seal containing pressurized fluid associated with the fluid end
Implementation Method 2
packing material positioned within at least a portion of the pressure ring bore
Implementation Method 3
the pressure ring positioned between the adjacent ring and the fluid end face
Data Source
AI summary
A system includes a fluid end having a fluid end face and a recess extending toward a base. The system also includes a pressure ring extending from the fluid end face, the pressure ring having a pressure ring bore diameter larger than a fluid end bore diameter. The system further includes an adjacent ring coupled to the fluid end, the pressure ring positioned between the adjacent ring and the base, wherein at least one fastener extends through an aperture of the adjacent ring to couple the adjacent ring to the fluid end. The system includes packing material positioned within at least a portion of the pressure ring bore, the packing material positioned such that axial movement toward the fluid end is blocked by the base.