What do chemical processors want in a PTFE gasket?

Don Horne   

Products ippt Pressure Pumps Valves

By Jim Drago

The search for the ideal Polytetrafluoroethylene (PTFE) gasket has been elusive. Competing applications and workplace variables have led to the creation of myriad solutions, yet none that has proven fully adaptable and appropriate for universal adoption.
Garlock Sealing Technologies considered this to be a critical yet entirely solvable shortcoming. And it is against this backdrop that in 2016, they set out to compile a comprehensive list of attributes for the ideal PTFE gasket — a wish list, as it were — in order to build a better gasket.
Working with a third-party survey development company, Garlock developed an exhaustive questionnaire that probed every aspect and functionality of PTFE gaskets, testing and adjusting the questions until they had a workable, finalized version.
Using this final questionnaire, Garlock conducted extensive interviews at 15 major chemical processor companies, speaking with 20 engineers responsible for process operations, projects, maintenance and reliability. The goal was simple: to discover the ideal characteristics and their relative importance that engineers sought in a PTFE gasket.
After several months of data collection, Garlock analyzed the feedback and noted the most popular responses:

  • 28 per cent of respondents said that they struggled with how different gaskets required different compressive loads and how to ensure that those gaskets had been installed properly
  • 21 per cent expressed frustration with the creep properties of PTFE gaskets
  • 21 per cent desired a gasket that seals with less compressive load
  • 14 per cent expressed frustration at the installation inconsistencies of their fitters
  • 14 per cent expressed frustration with leaking, especially after a successful installation and start-up

From those answers, Garlock drew the following conclusions, representing the most desirable and essential PTFE gasket characteristics:

  • Seal: Seals easily
  • Installation and assembly: Forgiving of poor installation or assembly practices
  • Forgiving: Forgiving of poor flange conditions
  • Retention: Maintains a seal after installation
  • Flexible: Can be used in a broad range of services to avoid user confusion and reduce inventory

Introducing: GYLON EPIX
Garlock used this feedback in developing a next generation PTFE gasket — GYLON EPIX. Featuring a hexagonal surface profile, GYLON EPIX offers superior compressibility and sealing for use in chemical processing environments. Its enhanced surface profile performs as well or better than existing 1/16″ or 1/8″ gaskets, allowing end-users and distributors to consolidate inventory, lower the risk of using incorrect gasket thicknesses and reduce stocking costs.
GYLON EPIX checks off the most desirable gasket attributes:

  • Installation and assembly: Even distribution of the bolt load over the contacted area of the gasket during the assembly process
  • Retention: Retention of the bolt load administered at assembly
  • Seal: Efficient translation of bolt load to sealing performance
  • Forgiving: The ability to perform in imperfect flanges and installation conditions

Figure A.

GYLON EPIX with its raised, hexagonal profile allows it to perform the job of both traditional 1/16” and 1/8” gaskets. It accomplishes this by combining the bolt retention of the former with the forgiveness for bad flange conditions of the latter, a truly innovative feature for PTFE sheet gasketing.
In action
Take the case of a PTFE gasket compressed in 3” Class 150 flat face flanges using pressure sensitive film inserted on the gasket surface. Whereas a traditional flat gasket displays load variations across the gasket surface, GYLON EPIX with its raised profile efficiently transfers the bolt load, dispersing it evenly over the entire gasket.
When it comes to sealing performance, GYLON EPIX also delivers (see fig. A), affecting a tight seal at compressive stresses far lower than traditional flat gaskets. This allows for sealing far earlier in the bolt assembly-compression process while facilitating the even distribution of the compressive load.
GYLON EPIX mitigates the creep associated with traditional PTFE gaskets. While all materials reach an integrity threshold at 500°F, GYLON EPIX retains a higher percentage of its initial load. It accomplishes this with its raised profile that optimizes bolt retention by facilitating the compression of the gasket to a thinner state, thus mitigating creep.

Figure B.

Finally, GYLON EPIX performs far better than traditional gaskets when sealing imperfect flanges. In laboratory conditions utilizing grooved test platens, GYLON EPIX sealed while traditional 1/8” gaskets did not. The ability to initiate a seal with adverse surface conditions distinguishes GYLON EPIX from its competitors.
Installs in all conditions. Seals easily and efficiently. Retains its sealing integrity in harsh conditions and imperfect flange conditions. Can be used in myriad applications. GYLON EPIX delivers innovative PTFE gasket technology and performance, the direct response to a critical industry need.
Jim Drago is the principal applications engineer at Garlock Sealing Technologies.

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