Kammprofile Gasket (Serrated Metallic Gasket) consist of a metal core, generally stainless steel with concentric grooves on both sides. A sealing layer is usually applied on either side and depending on the service duty the material for this layer can be expanded graphite, PTFE, Asbestos free gasket sheeting materials or some soft metal. It can be used without sealing layers to provide an excellent sealing but there is a risk of flange surface damage especially at high seating pressure.