Thermoseal® soft-chem® expanded PTFE sealing material provides excellent corrosion resistance and impermeability along with superior creep resistance and sealability for use in all types of applications. The material's high compressibility enables it to deform under load and conform to irregularities in flange faces for a tight seal with low, minimum sealing stress. Standardizing with it also helps to reduce maintenance, simplify inventory, and save money.

  • Can be used with more fragile piping systems
  • Ideal for boiler applications because it's largely unaffected by steam or condensate for longer life and trouble-free sealing
  • BAM approval for gaseous oxygen
  • Indefinite self life
  • FDA compliant

See graphs for temperature & pressure limits

Creep Relaxation ASTM F38B (1/32")


Sealability ASTM F37 B Fuel A

.002 ml/min

Gas Leakage DIN 3535/6

.12 ml/hr

Klinger Hot Compression Test

Thickness Decrease ambient, 3625 psi

Thickness Decrease Hot, 572°F (300°C)




Compressibility ASTM F36


Recovery ASTM F36

12% min

Tensile ASTM 152

1,500 psi

Vacuum to Full Pressure

3,000 psi

Chemical Resistance

0-14 ph


.85 g/cm3

Gasket constants as tested by Ecole Polytechnic



1,260 psi


.20 psi


3.5 psi

Pressure & Temperature Graphs:

The pressure/temperature graphs shown are the most current method of determining the suitability of a gasket material in a known environment. Use the pressure and temperature graphs to select the most suitable material for your application.

  • 1. In area one, the gasket material is suitable using common installation practices subject to chemical compatibility.
  • 2. In area two, appropriate measures are necessary for installation of the gasket to ensure maximum performance. Please call or refer to the KLINGER® expert software system for assistance.
  • 3. In area three, do not install gaskets in these applications without first referring to the KLINGER® expert software system or contacting Thermoseal Inc.'s technical support service

These graphs were developed from testing Klinger materials. Do not use them for competitors' materials since non-asbestos gasketing materials do not have service equivalents.

Use: The limitations of use, as shown in the graphs, are for guidance only, and are based on 1/16" thick material. The limitations of use decrease significantly as gasket thickness increases. Do not use a thicker gasket material or "double gaskets" to solve a gasket problem without first consulting the manufacturer. The ability of a gasket material to make and maintain a seal depends not only on the quality of the gasket material, but also on medium being sealed, the flange design, the amount of pressure applied to the gasket by the bolts and how the gasket is assembled into the flanges and tightened. Thermoseal engineers can advise on gasket selection and installation based on specified operating conditions. If you are in any doubt, fax us at 937.498.4911 or phone us at 937.498.2222.

For Additional Information Call Toll Free 1.800.990.7325 or email This email address is being protected from spambots. You need JavaScript enabled to view it.