Valve Plug Head Clamping for Field Replacement and Stress Relief

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Solution Overview

Problem

Existing valve plug designs face challenges in attaching and replacing plug heads due to stress-induced failures, limited material selection, and complex repair processes, particularly in high-temperature and corrosive environments, where taper and interference fits lead to uneven loading, material separation, and restricted service temperature ranges.

Innovation Solution

A clamping system using two retainer half-rings and sacrificial bolts/nuts to attach and detach plug heads from plug stems, allowing for easy field replacement and adjustment, utilizing dissimilar materials for optimal performance and simplifying assembly and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If taper fitting or interference fitting is used to attach plug head to plug stem, then the plug head can be securely attached, but stress concentration and uneven loading occur that lead to plug head failure

Engineering Contradiction:
Improveattachment strengthVSAvoidplug head reliability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The plug head is divided into two separate pieces: a ceramic insert providing erosion/corrosion resistance and a metal outer shell providing structural strength. This segmentation allows each material to perform its optimal function while being joined through a keyway and set screw mechanism that distributes stress evenly, avoiding the stress concentration problems of taper and interference fits.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The plug head uses a composite structure combining ceramic insert with metal outer shell. The ceramic provides resistance to erosion and corrosion while the metal shell provides structural integrity. The two materials are joined using a keyway and set screw arrangement that creates uniform stress distribution, eliminating the tensile stress concentration that occurs at the edges of taper and interference fits.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If multiple materials are used for plug head, then erosion and corrosion resistance is improved, but joining the materials creates stress points that limit plug head life

Engineering Contradiction:
Improveerosion and corrosion resistanceVSAvoidplug head life
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The plug head is divided into two separate pieces: a ceramic insert providing erosion/corrosion resistance and a metal outer shell providing structural strength. This segmentation allows each material to perform its optimal function while being joined through a keyway and set screw mechanism that distributes stress evenly, avoiding the stress concentration problems of taper and interference fits.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The plug head uses a composite structure combining ceramic insert with metal outer shell. The ceramic provides resistance to erosion and corrosion while the metal shell provides structural integrity. The two materials are joined using a keyway and set screw arrangement that creates uniform stress distribution, eliminating the tensile stress concentration that occurs at the edges of taper and interference fits.

Inventive Principle:
Principle #40Composite materials

3Strength

If taper fitting is used, then plug head can be attached to plug stem, but repair and replacement becomes difficult requiring specialized equipment

Engineering Contradiction:
Improveattachment strengthVSAvoidplug head replacement ease
Core Design Contradiction:
StrengthVSEase of repair

Solution Approach 1:

The plug head is divided into two separate pieces: a ceramic insert providing erosion/corrosion resistance and a metal outer shell providing structural strength. This segmentation allows each material to perform its optimal function while being joined through a keyway and set screw mechanism that distributes stress evenly, avoiding the stress concentration problems of taper and interference fits.

Inventive Principle:
Principle #1Segmentation

4Ease of manufacture

If monolithic material is used for plug head, then manufacturing is simpler, but erosion and corrosion resistance is reduced

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoiderosion and corrosion resistance
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The plug head is divided into two separate pieces: a ceramic insert providing erosion/corrosion resistance and a metal outer shell providing structural strength. This segmentation allows each material to perform its optimal function while being joined through a keyway and set screw mechanism that distributes stress evenly, avoiding the stress concentration problems of taper and interference fits.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The plug head uses a composite structure combining ceramic insert with metal outer shell. The ceramic provides resistance to erosion and corrosion while the metal shell provides structural integrity. The two materials are joined using a keyway and set screw arrangement that creates uniform stress distribution, eliminating the tensile stress concentration that occurs at the edges of taper and interference fits.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentUS10989315B2Method of attaching or replacing a plug assembly
Publication Date: 2021.04.27 FLOWSERVE PTE LTD
  • US10989315B2 patent drawing
  • US10989315B2 patent drawing
  • US10989315B2 patent drawing

AI summary

A plug assembly includes a plug stem having a plug stem base, a plug head, and a fastening mechanism for fastening the plug stem base to the plug head, the fastening mechanism comprising at least two retainer clamps that surround and provide an interference fit between the plug stem base and the plug head. A method of replacing or attaching a plug head to a plug stem includes providing a plug stem having a plug stem base, providing a plug head, providing a fastening mechanism comprising at least two retainer clamps, and coupling the fastening mechanism around the plug stem base and the plug head to provide an interference fit between the plug stem base and the plug head.