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Date: 07/08/02 at 3:43 PM
Posted by: Erik Baker
E-mail: etb8921@stargate.net

We work with a glass-filled Teflon packing assembly in a stem seal application for air-operated globe valves. The working fluid is exclusively water (no steam or two-phase) with a temperature range of 70-500 F and pressure range of 0 - 3000psi. Our packing vendor recently purchased a large batch of material where the pre-machined bars of glass-filled Teflon are below our specification requirements for this material. Specifically, the tensile strength ranges from 1700 - 2500 psi versus the accepted spec range of 2500 - 3200 psi. As such, the material also tested "low" for percent elongation (150-200 versus spec range of 200-300) and deformation under load at 73F, 24hrs. per ASTM D621 (7.5-10 percent versus spec range of 4-8 percent). Although some of the spec properties were not met, the vendor produced a small quantity of assemblies without any machining difficulties and appear that they may be potentially acceptable for use. The question we have is, are these deviations significant enough to preclude usage of packing in the service conditions provided? We are trying to evaluate whether it is worth spending tens of thousands of dollars to functionally test the samples provided to prove that they functionally work.

Thanks for your help!

Erik

Follow Ups:

  Re: 25% glass-filled Teflon packing properties kailash tiwari   Posted at: 08/02/03 (1)

  Re: 25% glass-filled Teflon packing properties kailash tiwari   Posted at: 08/14/03 (0)

  Re: 25% glass-filled Teflon packing properties Janine Kruit   Posted at: 07/09/02 (0)

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