In a recent article entitled Expert Advice Aids Selection of the Right Gasket Material which appeared in the September, 2013 issue of MRO magazine, Bill Searle of CRGI explained the benefits of polyfluorethylene (PTFE) gaskets. Choosing gaskets made from PTFE can provide significant advantages for the right applications.
As a gasket material, PTFE has many benefits. The two most notable are it has exceptional chemical resistance - there are only a few chemicals that will attack the polymer. In addition, PTFE can withstand temperatures up to 260°C (500°F). These two primary benefits make PTFE suitable for use in applications involving aggressive fluids and relatively high operating temperatures.
Despite its advantages, PTFE does, however, have one significant weakness: it tends to exhibit creep and/or cold flow characteristics under compressive loads, thus affecting the gasket’s performance. As a result, frequent retightening of PTFE gaskets is often required. Despite this tradeoff, PTFE can still be the material of choice for certain sealing applications. Users, therefore, should be sure they are dealing with a supplier who can provide the necessary application expertise to assist in the selection of the optimal material for a specific sealing application.
A wide range of PTFE materials is now available in the marketplace. These materials reflect different compounds and manufacturing processes, resulting in materials with different performance and cost characteristics. The performance and cost differences between these materials highlights why users may need guidance to select the most appropriate PTFE material for their needs.
For example, as Bill points out in his article, pulp and paper mills in Canada use a wide range of PTFE gaskets in their facilities, including those for applications using sodium hydroxide or sodium borohydride in the bleachery portion of the mill. For these applications, the specifications call for a PTFE gasket manufactured from a restructured sheet process, which is four times the price of a glass-filled, sintered process PTFE gasket. This again highlights why users may need expert help and guidance to select the most appropriate PTFE materials to balance costs against performance.
Find further details on PTFE gasketing and how it may help address some of your sealing needs in Bill Searle's full article published September, 2013 on page 20 of MRO magazine.