Metal Jacketed Gasket
Metal Jacketed Gaskets are the most basic type of semi-metallic gaskets combining the high pressure suitability and blow-out resistance of metallic material with the improved compressibility of soft material. Metal Jacketed gaskets offer an economical seal where sealing faces are narrow and can be produced in a variety of shapes, which makes them a good option for heat exchanger jointing. They are made from graphite, ceramic, non-asbestos etc. filler is covered with a thin metal jacket, such as stainless steel, carbon steel, copper etc. their sealing efficiently provide outstanding resilience, while the metal jacket with thickness 0.4 mm guarantees excellent sealing and protects the filler against pressure conditions, fluctuating temperature and corrosion. They are particularly suitable for sealing flat surface of heat exchanges, cast iron flanges, cylinder heads of engines as well as for boilers and other vessels. their sealing efficiently, provided by exerting strong pressure on circular rimes of the flanges, metal-jacketed gaskets can stand up to 30% deviation from the initial thickness, which is very useful in case of irregular or faulty flange rims. The chemical compatibility of the metal and the medium being sealed should be considered. The heat exchanger gaskets come in a wide spectrum of types including single or double jacketed, corrugated, plain metal, soft and many others. A large selection of different
material allows heat exchangers to operate at temperatures beyond the capabilities of most soft gasket materials.
The gaskets are used in shell and tube type heat exchangers. They can be manufactured in very different sizes, shapes; with or without bars. The primary seal is at inner diameter of the gasket, the outer gasket diameter acts as a secondary seal. Corrugated gaskets are a highly versatile family of products, available in wide variety of configurations and suited for a wide range of applications.
For improved sealing performance, the gaskets can be partially or completely covered. Metal jacketed and corrugated gaskets can suit a wide range of chemical environment which depends on the selection of a suitable alloy jacket or core.
Gaskets with integrated bars:
Traditionally double-jacketed gaskets for heat exchangers are manufactured with integrated bars.
There is a radius between the bars and an internal diameter of the gaskets. The values of the corresponding radius for the most commonly used metals and alloys are shown in the following table. If a radius is less than R min, the material can crack, which will cause reducing the sealing properties of the gaskets.
Gaskets with welded bars:
Gaskets with welded bars have eliminated one of the greatest problems of conventional gaskets, namely cracks in the radius area.
The primary and secondary seals are continuous all around the gasket.
The bars which seal between the heat exchangers passages are plasma or TIG welded with spot welds at each end. These welds should be soft and small to avoid areas of increased resistance to seating. Welding bar is economical.
Gaskets with outside diameter to 1000 mm are normally made with integrated bars. Gaskets with an outside diameter greater than 1000 mm are normally made with welded bars. According to the heat exchangers’ shapes and sizes other dimensions can be manufactured on request.