These PTFE envelope gaskets are available in the styles listed below:
Slit Envelope Gaskets - are essentially ring gaskets with 0. 020" thick leaves slit from the OD to approximately 3/64" from the id. These slit envelope gaskets are the most widely used gasket type in sizes for 1" to 12" OD.
Milled Envelope Gaskets - are made from PTFE cylinder stock, machined from their od to within 3/64" of the id. Milled envelope gaskets are available in standard sizes as well as various take-outs to accommodate your filler.
Formed Shield Envelope Gaskets - this design is used for large diameters and for irregular configurations, such as tank heads and manholes. A wide variety of elliptical and other irregular configurations are also available.
Double Jacket Envelope Gaskets - these envelope gaskets are recommended for vacuum service. The design of double jacket envelope gaskets completely covers the filler material with two overlapping PTFE jackets for optimum protection from corrosive attack.
CAF/Non Asbestos Gaskets are die cut or circle cut from compressed asbestos fibre/non asbestos jointing which are manufactured from carefully selected chrysolite fibre intimately blended with suitable heat resistant binders etc. and vulcanized into sheets of homogeneous compositions and uniform thickness. CAF/Non Asbestos cut gasket seal is effected by yielding or flow of material into the imperfections of joint contact faces. In this way gasket provides an unbroken barrier of homogeneous structure through which no pathway exist for escape of confined media.
Ring joint gaskets are produced from different solid metal types. They are used to stand high pressure and temperatures and they are employed where corrosive agents are present. These gaskets are obtained by mechanical working from forged or laminated metals in one single piece. They are employed in production and refining process of oil and chemical industries. Ring joint gaskets are strictly manufactured to api-6a/ASME b16. 2 specifications. Ring joint gaskets shall be either octagonal or oval in cross section and identify by r, rx or bx number that relates to flange size (NPS), pressure class and appropriate flange standards.
Special Spring like Metal strips are wound with an asbestos/PTFE/grafoil filler by a special process to assure a leakproof seal. The sealing is done by the asbestos filler and the metal strip provides the spring. This combination of metal and soft asbestos filler piles compresses to its predetermined thickness under bolting pressure and thereby prevents leakage within the limit of its specified pressure and temperature. Spiral Wound Gaskets can be adapted for use on many types of flanges and closures.