The critic operating conditions in specific device require a kind of gasket able to give a perfect sealing, to avoid heavy risks to health and environment due to leak at high pressure. The most common metallic gasket are Ring Joint, Lens.
At the beginnig Ring Joint gasket were developed for petrochemical industry due to needs to reach a good performance of sealing for high pressure and temperature. Most used section are the octagonal and oval ring joint. Both section can work with the same seat, even if it is necessary to make the proper maintenance for used seat.
Lens gasket has a particular geometry; contact surface is a spherical shape and are used for special application referred to pressure and temperature that can change during the time. Usually they are installed on flange connection of reactor for high pressure.
Plane Metallic gasket
Usually used on heat exchanger. To guide the settlement of the gasket on the flange contact, a surface called ‘Nubbin’ is present on one of the flange face reducing the load section to increase the specific pressure. Being metallic component, it is ever possible the compatibility with flange materials. Metal plane gasket can be obtained by forming the strip and subsequent welding, by multiple sectors welding and in a single piece of sheet metal.
Grooved Metallic gasket
Grooved metallic gasket is an upgrade of plane metallic one. They are different for the presence of grooving surface, with concentric circles, obtained by turning or milling form method.
The grooving surface, reducing the contact surface with flanges, allows the plastic deformation of gasket during the tightening, that is the necessary condition for sealing. Sometime the grooves leaves a mark on flanges and it could be possible a surfaces refacing for the next assembling.
This kind of gasket is supplied also for standard flanges. The grooving surface can be obtained by turning or milling form method.