Valve Stem Packing Layout With Inter-Packing Pressure Relief

Solution Overview

Problem

Conventional packing systems in valve assemblies face challenges in reducing fugitive emissions while minimizing friction and maintaining operational efficiency, especially in high-pressure and high-temperature applications, leading to increased maintenance costs and degraded dynamic performance.

Innovation Solution

A packing system with a bonnet configuration that exposes an inter-packing volume to downstream pressure, utilizing a labyrinth seal with a higher leakage rate upstream and a lower leakage rate downstream, and incorporating a vacuum source to reduce inter-packing pressure, along with a diagnostic method to monitor and control leakage rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional packing systems are used to prevent leakage, then fugitive emissions are reduced, but friction increases and operational efficiency decreases

Engineering Contradiction:

Improvefugitive emissionsVSAvoidoperational efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The packing system is divided into multiple packing arrangements (first packing arrangement and second packing arrangement) positioned at different locations along the stem. This segmentation allows each packing arrangement to handle a portion of the sealing function, reducing the friction and wear on any single packing arrangement while maintaining effective leakage prevention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An inter-packing volume is introduced between the first and second packing arrangements, which can be pressurized to act as an intermediary barrier. This intermediary volume helps to reduce the pressure differential across each individual packing arrangement, thereby reducing friction and improving operational efficiency while still preventing fugitive emissions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If packing material is arranged to prevent leakage, then fugitive emissions are limited, but maintenance costs increase due to degraded dynamic performance

Engineering Contradiction:

Improvefugitive emissionsVSAvoidmaintenance costs

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The packing system is divided into multiple packing arrangements (first packing arrangement and second packing arrangement) positioned at different locations along the stem. This segmentation allows each packing arrangement to handle a portion of the sealing function, reducing the friction and wear on any single packing arrangement while maintaining effective leakage prevention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inter-packing volume can be pressurized in advance to cushion the pressure differential before it reaches the packing arrangements. This prior cushioning reduces the stress on the packing materials, minimizing degradation and extending maintenance intervals while still preventing fugitive emissions.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If a single packing arrangement is used, then the structure is simple, but leakage prevention effectiveness is insufficient under high-pressure conditions

Engineering Contradiction:

Improvepacking structureVSAvoidleakage prevention

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The packing system is divided into multiple packing arrangements (first packing arrangement and second packing arrangement) positioned at different locations along the stem. This segmentation allows each packing arrangement to handle a portion of the sealing function, reducing the friction and wear on any single packing arrangement while maintaining effective leakage prevention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution adds a spatial dimension by introducing an inter-packing volume between the packing arrangements. This additional dimensional element allows for pressure management that enhances leakage prevention without significantly increasing structural complexity, as the inter-packing volume utilizes existing space in the valve assembly.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Object-affected harmful factors

If packing arrangements are positioned to maximize sealing, then leakage is reduced, but friction and operational stress increase

Engineering Contradiction:

ImproveleakageVSAvoidfriction

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

An inter-packing volume is introduced between the first and second packing arrangements, which can be pressurized to act as an intermediary barrier. This intermediary volume helps to reduce the pressure differential across each individual packing arrangement, thereby reducing friction and improving operational efficiency while still preventing fugitive emissions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Some of the sealing function is extracted from the packing arrangements themselves and transferred to the inter-packing volume. By pressurizing the inter-packing volume, a portion of the leakage prevention responsibility is taken out from the packing materials, reducing their friction and wear while maintaining effective sealing.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration reduces fugitive emissions, decreases friction, and improves operational efficiency by allowing leakage to divert to downstream systems rather than the atmosphere, while the diagnostic method ensures timely maintenance and reduces operational stress on the packing system.

Implementation Method 1

The bore port can provide fluid communication between the inter-packing volume and the outlet of the valve

Methodology Applied

Scientific EffectFluid communication:

Implementation Method 2

a first packing arrangement that is a labyrinth seal configured to have a first leakage rate that is greater than a second leakage rate of a second packing arrangement

Methodology Applied

Scientific EffectLabyrinth seal:

Implementation Method 3

incorporating a vacuum source to reduce inter-packing pressure

Methodology Applied

Scientific EffectVacuum: Vacuum

Data Source

PatentUS12181052B2Packing system and diagnostic method for a packing system of a valve assembly

Publication Date: 2024.12.31 FISHER CONTROLS INT LLC

AI summary

A packing system is disclosed for use with a valve having a bonnet and a flow passage extending between an inlet and an outlet of a valve body. A bore can extend through the bonnet to receive a stem that moves a control member to control flow through the flow passage. A first packing arrangement can be arranged in the bore about a first portion of the stem. A second packing arrangement can be arranged in the bore about a second portion of the stem with the first packing arrangement between the second packing arrangement and the valve body. A bore port can extend through the bonnet and open into an inter-packing volume of the bore between the first and second packing arrangements and can provide fluid communication between the inter-packing volume and the outlet of the valve or other lower pressure area.