PTFE ENVELOPE GASKET

Envelope gasket utilizing PTFE jacket have become popular for use in severely corrosive services because of their low minimum seating stresses, excellent creep resistance, high deformability and choice of a variety of filler materials to assure optimum performance on any specific application. Fillers such as corrugated metal and rubber sheets are available.

There Are Three Basic Designs Of Envelopes:
Slit Type: sliced from cylinders and split from the outside diameter to within approximately 1/16” of the inside diameter. The bearing surface is determined by the filler dimensions. Clearance is required between the I.D. of the filler and the envelope I.D. The gasket O.D. normally rests within the bolt hole circle and the I.D. is approximately equal to the nominal I.D. of pipe. Available in sizes to a maximum O.D. of 24”.

Milled Type: machined from cylinder stock. The jacket is machined from the O.D. to within approximately 1/32” of the I.D. The jacket I.D. fits flush with pipe bore and the O.D. nests within the bolts. Available in sizes up to a maximum O.D. of 24”. Milled envelopes are more expensive than slit type since considerably more material is lost in machining.

Formed Tape Type: large diameter (over 12” NPS) and irregularly shaped envelops are formed from tape and heat sealed to produce a continuous jacket construction.