Seal Ring Alloy Composition for High-Pressure Severe Service

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Solution Overview

Problem

The challenge is to produce seal rings for machinery that can withstand high-pressure, high-speed, and high-deflection environments while reducing material costs without compromising performance, as existing seal rings made from expensive alloys are not economically viable for long-term severe service applications.

Innovation Solution

A seal ring alloy composition is developed with specific weight percentages of iron, silicon, chromium, boron, carbon, and nickel, which replaces some nickel with iron to decrease costs while maintaining performance, and the seal rings are manufactured using suitable methods such as centrifugal casting and machining to achieve precise tolerances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-cost materials are used for seal rings, then performance and durability are improved, but manufacturing cost increases

Engineering Contradiction:
Improveseal ring performanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by precisely controlling the chemical composition parameters of the alloy, specifically maintaining nickel content at 65-75%, chromium at 14-16%, iron at 6-9%, silicon at 1.5-3%, boron at 2-3%, and carbon at 2-3%. This optimized parameter range achieves the desired balance between cost reduction and performance maintenance by minimizing nickel content while ensuring adequate corrosion resistance and sealing performance through the synergistic effect of other alloying elements

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite alloy material that combines multiple elements (nickel, chromium, iron, silicon, boron, and carbon) in specific proportions to achieve properties that cannot be obtained by single elements alone. The composite structure provides both cost reduction (through reduced nickel) and performance maintenance (through chromium for corrosion resistance, boron for hardenability, and carbon for strength)

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If nickel content is reduced to decrease cost, then manufacturing cost decreases, but corrosion resistance may worsen

Engineering Contradiction:
Improvematerial costVSAvoidcorrosion resistance
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the parameter ranges of multiple alloying elements simultaneously, not just nickel. Chromium is maintained at 14-16% (higher than conventional alloys) to provide excellent corrosion resistance, boron is set at 2-3% to improve hardenability and surface properties, and carbon is kept at 2-3% to ensure adequate strength. This multi-parameter optimization compensates for reduced nickel while maintaining or improving corrosion resistance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent develops a composite alloy where chromium, boron, and carbon work synergistically to replace the protective function of nickel. Chromium forms a passive oxide layer for corrosion protection, boron enhances surface hardness and wear resistance, and carbon provides structural strength, collectively compensating for the reduced nickel content while maintaining overall material performance

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3667135B1Alloy for seal ring, seal ring, and method of making seal ring for seal assembly of machine
Publication Date: 2022.06.08 CATERPILLAR INC
  • EP3667135B1 patent drawingFigure 1
  • EP3667135B1 patent drawingFigure 2
  • EP3667135B1 patent drawingFigure 3~4

AI summary

A seal ring (111, 112) for a seal assembly (30, 36) includes a body (240) and a seal flange (137). The body (240) is generally cylindrical and extends along a longitudinal axis (LA) between a load end (131) and a seal end (132). The seal flange (137) is disposed at the seal end (132) of the cylindrical body (240). The seal flange (137) circumscribes the body (240) and projects radially from the body (240) to a distal perimeter (138) of the seal flange (137). The seal flange (137) includes a sealing face (136) which is annular and disposed adjacent the distal perimeter (138). The seal ring (111, 112) is made from an alloy that includes between 6 percent and 9 percent by weight of iron, between 1.5 percent and 3 percent by weight of silicon, greater than 14 percent by weight of chromium, and at least 65 percent by weight of nickeL