Live-Loading Packing Apparatus with Force Indication Scale
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Solution Overview
Problem
Existing packing systems in fluid handling devices face challenges in accurately determining the force applied to the packing, leading to improper loading and leakage issues due to human error and material volume changes with temperature variations, which conventional live-loading systems cannot effectively address.
Innovation Solution
A dynamically-loaded packing system with a spring cartridge and calibrated piston rod that indicates the force applied to the packing through a visible scale, using a stack of Belleville springs to maintain consistent pressure and accommodate thermal expansion, ensuring accurate force measurement and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional torque wrenches are used to tighten gland bolts, then installation is simplified, but inaccurate torquing occurs leading to improper loading
Solution Approach 1:
The patent incorporates a feedback mechanism where the actual compressive force applied to the packing is continuously measured and displayed on a gauge. This allows operators to see in real-time whether the packing is being compressed within the optimal range, providing immediate feedback to adjust bolt tightness accordingly, thereby eliminating the inaccuracy of conventional torque wrenches.
Solution Approach 2:
The patent replaces the mechanical torque-wrench system with a spring-loaded measurement system. Instead of relying on torque conversion, the system directly measures compressive force through springs that deflect proportionally to the force applied, with this deflection displayed on a gauge. This substitution of mechanical torque measurement with direct force measurement eliminates the inaccuracies inherent in torque wrench usage.
2Reliability
If packing compression is increased to prevent leakage, then sealing performance improves, but excessive compression damages the packing
Solution Approach 1:
The gauge provides visual feedback showing the actual compressive force on the packing. Operators can adjust the gland bolts while monitoring the gauge to ensure the compression remains within the optimal range indicated by scale markings, preventing both insufficient compression (leakage) and excessive compression (damage).
Solution Approach 2:
The patent introduces a visual parameter system with scale markings that indicate optimal compression ranges. By changing the parameter display from hidden mechanical stress to visible gauge readings, operators can directly observe and control the compression parameter to maintain it within safe and effective limits.
3Reliability
If live-loading with Belleville springs is implemented, then continuous pressure is maintained, but force measurement becomes difficult
Solution Approach 1:
The patent introduces a gauge as an intermediary device that translates the complex spring compression into a readable visual indication. The gauge acts as a mediator between the Belleville springs and the operator, making the force measurement straightforward while maintaining the continuous pressure benefits of live-loading.
Solution Approach 2:
The patent replaces the difficult-to-measure spring compression system with a gauge-based measurement system. Instead of trying to directly measure spring force, the system uses a gauge with scale markings to visually indicate the compressive force, making measurement simple while preserving the continuous pressure maintenance capability.
4Temperature
If packing materials are improved for temperature resistance, then thermal stability improves, but volume expansion characteristics remain problematic
Solution Approach 1:
The patent implements a dynamic compression system using Belleville springs that automatically adjust to packing volume changes. As the packing expands or contracts with temperature variations, the springs dynamically adjust the compressive force to maintain consistent pressure, compensating for volume variations without requiring material changes.
Solution Approach 2:
The patent changes the control parameter from fixed bolt torque to dynamic spring force. The spring-based system allows the compression parameter to vary dynamically with temperature and packing volume changes, automatically maintaining optimal pressure despite thermal expansion and contraction of the packing material.
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 system provides continuous self-adjustment and precise force indication, reducing leakage and maintenance needs by accurately maintaining the necessary pressure on the packing, as demonstrated by improved gland stress retention and fugitive emission test results.
Implementation Method 1
A dynamically-loaded packing system with a spring cartridge and calibrated piston rod that indicates the force applied to the packing through a visible scale, using a stack of Belleville springs to maintain consistent pressure and accommodate thermal expansion
Implementation Method 2
A dynamically-loaded packing system with a spring cartridge and calibrated piston rod that indicates the force applied to the packing through a visible scale
Data Source
AI summary
A live-loading assembly for exerting a sealing force on a compressible packing structure of a fluid handling device, such as a valve or pump, includes a pair of gland bolts each movably extending through opposite end lids of a tubular cartridge and through a Belleville spring stack disposed within the cartridge and bearing on a tubular piston rod having an end portion extending outwardly through one of the lids and having a spring force indicating scale disposed thereon. When packing force adjustment nuts are tightened onto the bolts, to increase the compression force exerted on the packing structures, one of the lids on each cartridge moves along the associated exposed piston rod scale to thereby provide a visual indication of the amount of spring force being created by each tightened nut.