Due to the high demands on the safety of gasketed joints and the current requirements with respect utmost tightness, choice and fitting of the right gasket with the proper expertise is a must. Accordingly a number of requirements have to be met by the gasket materials and the complete flange joint to obtain a reliable sealing connection.
Adjustment to the unevenness of the sealing surface. This depends on the compressibility of the gasket, the surface condition of the sealing surface and surface load.
Resistance to the fluid to be sealed. When selecting the gasket, care should be taken to ensure that the sealing material is resistant to the fluid under service conditions. In general, properly loaded gaskets show better resistance than under loaded gaskets.
Strength of the sealing connection. The mechanical behavior of the gasket is determined by the complete joint system. Increasingly high requirements on the tightness of flange joint (e.g. tightness class L0.01) require the application of high surface loads on the gasket as the internal pressure is increased. Under such operating conditions, the selected flange joint must be assessed for its suitability to these loads in order that mechanical overload is avoided. A tight gasket joint requires a defined surface load.
The service life of the gasket also depends on the fact the gasket stress must always be higher than the minimum surface load required to prevent leaks.Higher-loaded, but not overloaded, gaskets have a longer life than underloaded ones. Special gasket materials for water/steam applications which display no embitterment at temperature, if it cannot be guaranteed that the fitted gasket will only be subjected to static stresses, or if stress fluctuations can be assumed in discontinuous operation. In the case of gaskets used in discontinuous water/steam circuits, we recommend a min. surface load in service of approx. 30 MPa. In such applications, the gasket should be as thin as technically possible and practical.
Tightness depends on the surface load applied at fitting and in operation. A gasket which is selected and fitted according to these instructions will have a long service life. For safety reasons, re-use of gaskets is not recommended.
The max. permissible surface load of a gasket material is a function of pressure, temperature and gasket thickness and must not be surpassed. The gasketed joint remains tight as long as the surface load present in service is higher than the required min. surface load and the maximum permissible surface load BO of the gasket is not surpassed.
Required gasket thickness. No general rule exists to determine the required gasket thickness. In most cases, 2 mm thickness will suffice. Thinner gaskets allow higher surface loads.
Low-temperature range applications. Our gaskets are also suitable for very low temperatures. A pre-requisite for a tight connection is that the required surface load is maintained over the complete temperature range. Fluid resistance is guaranteed to -196Â°C. In the low-temperature range, the material must not be exposed to additional loads.