Polished Rod Liner Assembly High-Pressure Sealing
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Solution Overview
Problem
Conventional liner clamps for polished rods in reciprocating pump systems fail to effectively seal the annular space, leading to leakage and pressure limitations, especially at higher working pressures due to their design and material limitations.
Innovation Solution
A liner assembly comprising a liner, a nut, and a head with a gasket, featuring a deepening external thread and tapered internal thread configuration, which provides a sealing threaded connection to enhance sealing efficacy and withstand higher pressures up to 2250 psi.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liner clamps are used to affix the liner to the polished rod, then the structure is simple and easy to manufacture, but the sealing performance deteriorates and leakage occurs at higher pressures
Solution Approach 1:
The clamp assembly is divided into separate components: a clamp body with first clamping surfaces and a clamp member with second clamping surfaces. This segmentation allows each component to be optimized for its specific function while maintaining overall sealing performance through coordinated action of multiple surfaces.
Solution Approach 2:
Different regions of the clamp assembly have specialized features: the clamp body includes first clamping surfaces positioned to engage the liner, while the clamp member includes second clamping surfaces positioned to engage both the liner and the clamp body. This local differentiation of clamping surfaces creates multiple sealing zones that collectively prevent leakage at high pressures.
2Stress or pressure
If conventional threaded connections are used in the liner clamp, then the manufacturing is simple, but the pressure resistance deteriorates and cannot withstand pressures up to 2250 psi
Solution Approach 1:
The threaded connection parameters are modified with a deepening external thread profile and a tapered internal thread profile. The deepening external thread increases engagement depth and surface area, while the tapered internal thread creates a wedge effect that distributes stress more evenly. These parameter changes enable the connection to withstand pressures up to 2250 psi while remaining manufacturable using standard threading processes.
3Object-generated harmful factors
If the liner is made with greater diameter to reduce stuffing box leakage, then the leakage reduction is achieved, but the annular space sealing becomes more difficult
Solution Approach 1:
A flexible gasket is introduced as a thin film element within the clamp assembly. The gasket is positioned to seal the annular space between the liner and the polished rod. This flexible element conforms to the surfaces it contacts and maintains sealing under pressure, effectively preventing annular space leakage while allowing the liner to have a greater diameter for stuffing box leakage reduction.
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
The assembly effectively seals the annular space, preventing leakage and maintaining structural integrity at higher pressures, significantly improving the sealing performance and operational reliability of reciprocating pump systems.
Implementation Method 1
featuring a deepening external thread and tapered internal thread configuration, which provides a sealing threaded connection to enhance sealing efficacy
Implementation Method 2
The gasket is configured to seal the annular space between the liner and the polished rod
Implementation Method 3
the clamp members are configured to compress the gasket together
Data Source
AI summary
A liner assembly is used for a polished rod of a reciprocating pump movable through a stuffing box. A liner sleeve positions on the polished rod and has an external thread on its distal ends. Roots of the external thread increase in depth in the external circumferential surface along the length toward the distal end. A nut positions on the polished rod and has internal thread configured to thread to the external thread of the liner sleeve. A head positions on the polished rod. The head is configured to engage the polished (e.g., with clamping or fastening), and the head is configured to affix to the nut (e.g., with thread or with flanges and fasteners). A gasket positions on the polished rod between the nut and the head. The gasket is held between a nose of the nut and a smooth bore relief of the head or is held between reliefs on the nut and head.