Generally, PTFE is a tough, flexible, non-resilient material of average tensile strength but with great thermal properties and excellent resistance to chemicals and passage of electric current. The coefficient of friction is unusually low and believed to be lower than any other solids. PTFE is an outstanding insulator over a wide range of temperatures and frequency. The volume resistivity is above 1018 (Ω.m) with power factor very negligible over a huge range of temperatures. The chemical resistance of PTFE is outstanding, there are no solvents which could dissolve PTFE at room temperature and the surface of PTFE at room temperature is affected only by molten alkali and fluorine in some cases.
1. Brush off any rust or foreign particles. Wipe flange surface thoroughly with a rag soaked in acetone or other suitable solvent to remove grease or oil. 2. Insert fingernail between the paper backing strip and the tape and strip the paper back three to six inches. Draw a reference line in flange and press squared off end of tape against it. 3. Now, start laying the tape along the face of the flange, peeling the paper backing as you go. To prevent the adhesive surfaces of the tape from doubling back on themselves and sticking together, strip away only a few inches of paper at a time.
Clean radius and straight cuts are achievable on gasket material with the proper tooling. Thinner types of gasket material require nothing more than sharp blades and hollow gasket cutters. Gasket material over 1/4-inch thick require specialized mechanical tools to create the precision cuts necessary to seal a piece of equipment and is best left to professionals. Properly securing the gasket material and ensuring the tools used are in good condition will allow you to cut thinner gasket material efficiently and precisely.
In the present seal, metal spiral wound gasket with excellent elasticity, high temperature, high pressure,low temperature and other characteristics, has become a very wide range of applied seal. Especially suitable for uneven loading, relaxation and easy access together, cyclical changes in temperature and pressure of the occasion, is the main flange gasket. In the petrochemical pipelines, mechanicalseals,shipbuilding,metallurgy, aerospace and other industries widely.
There are two major factors to be considered with regard to gasket seating. The first is the gasket material itself. The ASME Unfired Pressure Vessel Code Section VIII, Division 1 defines minimum design seating stresses for variety of gasket materials.
A seal is affected by compressing the gasket material and causing it to flow into the imperfections on the gasket seating surfaces so that intimate contact is made between the gasket and the gasket seating surfaces preventing the escape of the confined fluid. Basically there are four different methods that may be used either singly or in combination to achieve this unbroken barrier.