Hydrogen Gas Expansion Joint Bellow with Epichlorohydrin Barrier
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Solution Overview
Problem
Existing rubber expansion joints for hydrogen-containing gases suffer from high hydrogen permeation, reduced mechanical stability due to hydrogen embrittlement, and inadequate burst pressure, making them unsuitable for high-pressure applications.
Innovation Solution
The use of an inner layer made of epichlorohydrin rubber and stainless steel type 1.4404 rings, combined with a textile reinforcement layer, enhances hydrogen permeation resistance and mechanical stability, achieving a high burst pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If NBR rubber is used for the inner layer, then the expansion joint can be manufactured with standard materials, but hydrogen permeation loss increases significantly
Solution Approach 1:
The patent changes the chemical composition parameter of the inner rubber layer from NBR to epichlorohydrin rubber, which has different permeability characteristics. This material substitution fundamentally alters the hydrogen permeation properties while maintaining the manufacturing process compatibility
Solution Approach 2:
The patent creates a composite structure with multiple rubber layers (inner epichlorohydrin rubber layer, outer NBR layer) where each layer serves a specific function. The inner layer provides hydrogen permeation resistance while the outer layer provides environmental resistance, achieving a balance between contradictory requirements
2Ease of operation
If standard steel rings are used, then the expansion joint can be assembled easily, but mechanical stability decreases due to hydrogen embrittlement
Solution Approach 1:
The patent changes the material parameter of the end rings from standard steel to stainless steel type 1.4404, which has different chemical composition and corrosion resistance properties. This substitution maintains the mechanical function while eliminating hydrogen embrittlement susceptibility
Solution Approach 2:
The patent replaces the inexpensive but vulnerable standard steel rings with more expensive but durable stainless steel rings, trading initial cost for long-term reliability and extended service life in hydrogen service
3Device complexity
If conventional expansion joint design is used, then the structure remains simple, but burst pressure falls short of the required 5x operating pressure
Solution Approach 1:
The patent introduces a textile reinforcement layer composed of multiple plies (radial and circumferential) between the inner and outer rubber layers. This composite reinforcement structure significantly enhances burst pressure while maintaining a relatively simple overall geometry
Solution Approach 2:
The patent adds a dimensional element by inserting a textile reinforcement layer with specific ply orientations (radial and circumferential directions). This multi-directional reinforcement architecture distributes stress more effectively, achieving higher burst pressure without substantially increasing structural complexity
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 solution provides a bellow with low hydrogen permeability, improved mechanical stability, and increased safety by preventing hydrogen accumulation, while maintaining elasticity and durability.
Implementation Method 1
the inner rubber layer needs to act as a permeation barrier... NBR as the rubber inner layer is not an optimal material for hydrogen containing gases in terms of hydrogen permeation resistance
Implementation Method 2
the steel wire typically used in the expansion joints have a low resistance to hydrogen embrittlement due to the used steel alloy... stainless steel type 1.4404 could provide a bellow which achieves good hydrogen permeation resistance and maintains mechanical stability
Implementation Method 3
several layers of reinforcement cord are located between the inner rubber layer and an outer rubber layer to ensure that high pressures inside the expansion joint can be withstood
Data Source
AI summary
The present invention relates to the use of a bellow for a rubber expansion joint for the transport of a gas containing hydrogen, wherein the bellow comprises an inner rubber layer based on epichlorohydrin rubber, an outer rubber layer, a textile reinforcement layer between the inner rubber layer and the outer rubber layer comprising one or more textile reinforcement plies including threads embedded in a rubber ply, wherein the bellow is provided at each of the open ends of the bellow with a ring made of stainless steel type 1.4404.