Design Considerations for Static Seals: Integrating Material Properties into Design 2012-01-0541

There are a number of approaches people take to develop solutions for static sealing applications. People use a range of designs for different situations intended for particular exposure conditions to different environments and expected levels of performance. In most cases, people look at seal design and material selection as two different and separate parts of a process that involve 1) selecting a material believed to be capable of acceptable performance in an environment, 2) selecting a design thought appropriate for an application, and 3) performing a durability test on the part made of that material in a simulated environment for the application. This works in most cases, but at best, it can only be characterized as an approach based on reasonable judgment, and trial and error.

What I intend to present is a sealing design approach that integrates the material response into the design, and uses the configuration and requirements of the applications to drive the design, where data generated on the materials in configurations can be integrated into the design. It will focus on the development of a sealing force or sealing pressure, as a result of compression of the seal, and how that force changes over time and at different temperatures to allow prediction of performance in an application. It will discuss a parametric approach to material testing that could enable small standard samples to be evaluated in an appropriate manner, to generate data sets that could be used to define capability and service life on the full seal design. It involves developing design windows around the material and configurations, so that you not only know if a seal will work, but under what conditions failures could occur.

Knowing more about the potential performance of a sealing system as a function of materials and their design windows, allows one to make better judgments about the tradeoffs between materials and design, and their impact on cost. This approach to design and development will be compared to other technical papers and books written on the subject, general industry practice, and considerations in using Finite Element Analysis (FEA).