Wave Washer Spring Portion for PTFE Seal Cold Flow Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional PTFE-lined pipe flange joints experience leaks due to thermal cycling and mechanical creep, requiring frequent re-torquing of flange bolts, which is labor-intensive and costly, especially in systems with multiple joints or hard-to-access locations.
Innovation Solution
A wave washer with an annular member and circumferentially spaced holes, featuring a spring-portion protrusion, is used between pipe flanges to maintain sealing pressure by compensating for load loss due to cold flow through elastic deformation and live load application on flange bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional PTFE-lined flange joints are used with plastic seals, then the piping system can be constructed with fluid contact only with plastic material, but the plastic seal experiences cold flow and thins out over time, causing leaks and requiring re-torquing
Solution Approach 1:
A wave washer is introduced as an intermediary component between the flange bolts and the PTFE sealing flange. The wave washer includes a Belleville spring that applies continuous resilient force to compensate for the cold flow of the plastic seal, maintaining sealing pressure without requiring re-torquing of the bolts.
Solution Approach 2:
The wave washer changes the mechanical parameter of sealing pressure by introducing a spring element that dynamically adjusts the force applied to the sealing flange. As the PTFE material undergoes cold flow and compresses, the spring expands to maintain constant sealing pressure, compensating for the dimensional changes in the plastic seal.
2Reliability
If flange bolts are re-torqued periodically to compensate for cold flow, then the seal integrity can be maintained, but the maintenance process becomes labor intensive and costly
Solution Approach 1:
The wave washer with Belleville spring provides self-service by automatically compensating for seal degradation. The spring continuously applies resilient force to counteract the cold flow of the PTFE seal, maintaining sealing pressure without requiring human intervention or periodic re-torquing operations.
Solution Approach 2:
The wave washer is pre-installed with the Belleville spring compressed to a predetermined extent during initial assembly. This preliminary compression stores elastic energy that is gradually released as the PTFE seal undergoes cold flow, providing continuous compensation without requiring subsequent maintenance actions.
3Reliability
If higher initial torque is applied to flange bolts to account for cold flow, then the seal may remain intact longer, but the risk of bolt failure or flange damage increases
Solution Approach 1:
The wave washer introduces dynamics to the static bolted joint by incorporating a Belleville spring that can dynamically adjust the sealing force. Instead of relying on high initial torque that risks bolt failure, the spring gradually exerts force as the PTFE seal compresses, distributing the mechanical load over time and preventing sudden stress peaks on the bolts and flanges.
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 wave washer maintains a fluid-tight seal by applying a live load to flange bolts, reducing the need for frequent re-torquing and minimizing maintenance, thus providing a cost-effective and leak-free pipe joint connection.
Implementation Method 1
maintain sealing pressure by compensating for load loss due to cold flow through elastic deformation and live load application on flange bolts
Data Source
AI summary
A wave washer includes an annular member surrounding an opening arranged to receive a pipe axially therethrough, the annular member having a plurality circumferentially spaced holes formed therein. The wave washer also has associated with it at least one spring portion protruding axially from the annular member between two of the holes. The wave washer can be used in a pipe joint to join a first pipe and a second pipe, each having a pipe end having a pipe flange and an adjacent sealing flange. The wave washer is positioned against an inner side of the pipe flange of the first pipe. The wave washer and the flanges of the first and second pipes are fastened based on the deflection of the annular member of the wave washer.