Your contact for grooved gaskets

Your contact for grooved gaskets

High pressures and temperatures - master high screw forces

Grooved gaskets

Grooved gaskets have proven extremely useful in all areas of industry, including the most demanding sealing tasks. Our grooved gaskets can be found in conventional power plants as well as in the primary circuit of nuclear power plants. In nuclear power plants, they are used e.g. as a heat exchanger gasket, as a valve cap gasket or as a manhole cover gasket on steam generators or pressurisers. Grooved gaskets have also been used to great success in the chemical and petrochemical industries.
Particularly in places where there are high pressures and temperatures, and therefore high bolt loads, to contend with. In order to avoid damage to the flanges by the metal core, grooved gaskets are generally used with layers of PTFE, graphite, aluminium or silver. This gives total protection to the flanges, as the profile geometry has been specifically adjusted to suit the thickness of the layer. We have developed a range of profiles to suit the various properties of the layer materials. The principal purpose of the soft layers is not however to protect the flanges, but to provide a secure seal even at low minimum surface pressures. A triaxial stress is created in the profiling of the metallic carrier which has been filled with the layer material. The load capacity is limited by the breaking point of the gasket and/or flange material. The stability of this combination is therefore significantly higher than with a pure PTFE, graphite, aluminium or silver seal.
Grooved gaskets be produced in sizes ranging from a few millimetres to a diameter of 4,500 mm on our lathes.

The possibility of producing gaskets with greater diameters or one-off production from drawings, such as oval gaskets, can be examined in individual cases.

For gaskets in heat exchangers with partitions, it is necessary to insert partitions with grooves of the same profile. Gaskets for flanges with raised face or for smooth flanges are supplied with a centring ring, so that the gasket is centred on the bolts. If the width of the centring ring is <= 10 mm, then this ring is a part of the gasket (fixed central frame). At greater widths, the integrated has a stress-relieving groove. A loose centring ring should be used with gaseous media. The loose centring ring is also advantageous where there are large differences in temperatures between internal and external diameters. The loose centring ring is fitted in a groove. The illustrations show the layout for a nominal thickness of the metal core of 4 mm.

TypeProfileCross-sectionDescriptionApplicationAdvantage
StandardB7A The B7Aprofile is for use with flange connections with tongue and groove and male and female faces. 
StandardB9Aintegrated centring ringThe Profile B9A with integrated centring ring should be selected for use with smooth flanges and flanges with raised face. 
StandardB15Aloose sheet metal central edgeWith gaseous media, or where there are large differences in temperature between internal and external diameters, the Profile B15A with loose sheet metal centring ring should be used. 
balligB27A For use with flange connections with tongue and groove and male and female faces.The convex grooved gaskets in Profile B27A, B29Aand B25A exhibit improved sealing properties compared to standard grooved profiles. The improvement is achieved by the decreasing depth of the
groove troughs towards the midpoint of the profile. The profiling is created as a step profile. The sealing layer made from soft, plastic deformable material creates a thicker padding at the profile centre line than in the internal and external zones. The layer thickness for graphite, aluminium and silver should be 0.5 mm and for PTFE 0.35 mm. The specific surface pressure is greatest at the profile centre line, causing the sealing layers to flow well into the unavoidable irregularities and roughness on the flange surface. Grooved gaskets in Profile B27A, B29A and B25A reduce edge pressure. The increased surface pressure at the profile centre line has a positive effect on the sealing properties in tilted flanges. With ordinary gaskets, when a flange is strongly tilted (α ~ 1°) it causes a raising of the internal diameter of the gasket to be observed, as the flange is now loading the seal more on the outer diameter. But with Profile B27A, B29A and B25A the contact diameter is kept at dG. These gaskets are therefore particularly suitable for flange connections where the pressures and temperatures are constantly fluctuating.
balligB29Aintegrated centring ringThe Profile B29A with integrated centring ring should be selected for use with smooth flanges and flanges with raised face
balligB25Aloose sheet metal central edgeWith gaseous media or large differences in temperature between the internal and external diameters, Profile B25A with loose sheet metal central edge should be used.
 
Profile
 
    
1.0038 & Graphit
 
 
1.5415 & Graphit
 
 
1.5415 & PTFE
 
 
1.4541 & Graphit
 
 
1.4541 & PTFE
 
 
1.4828 & Graphit
 
 
1.4541 & Aluminium
 
 
1.4541 & Silver
 
 
1.4828 & Silver
 
 
1.7335 & Graphit 
 
 
1.7335 & PTFE
 
B7A,
B9A,
B15A
Recommended max. roughness of the flange surfacesµmvon   2550 12,512,5 2550
bis   50100 2525 50100
Surface pressure limits for 20 °CN/mm²σv   1515 80125 1515
σϑ   500500 500500 450450
Surface pressure limits for 300 °CN/mm²ơσv   3030 95140 3030
σϑ   420420 420420 390390
B27A,
B29A,
B25A
Recommended max. roughness of the flange surfacesµmvon25255025502512,512,512,5  
bis50501005010050252525  
Surface pressure limits for 20 °CN/mm²σv15151515151570100100  
σϑ350450450500500500500500500  
Surface pressure limits for 300 °CN/mm²ơσv20202020202080110110  
σϑ210330330420420420420420500