When a raised-face flange is mated with a flat-face flange, measures should be taken to prevent the flanges from over...

In connection systems, the combination of raised face flanges (RF) and flat face flanges (FF) is uncommon, as the surface profiles of the two types of flanges do not match. A raised-face flange has a protruding surface, while a flat-face flange has a flat surface. When it is necessary to connect these two flanges together, special measures must be taken to prevent overload or damage to the flanges due to misalignment. \"SH3059-2012\" is a standard in China’s petrochemical industry. Its requirements regarding flange connections state, as you cited, that when a metal flange is connected to a flange made of non-metallic or brittle material, it is recommended to use full-flat flanges on both sides. If it is indeed necessary to use a raised-face flange in combination with a flat-face flange, measures to prevent overloading of the flanges may include: 1. Selection of gaskets: Choosing the appropriate material and thickness for the gaskets so that they can adequately fill in any irregularities between the two flanges and provide good sealing performance. 2. Adapter plate: Use a properly designed adapter plate to bridge the gap between the convex surface and the flat surface. This adapter piece may have a protruding portion that fits with the protrusion of the raised flange, while the other side is flat to match the fully flat flange. 3. Strengthening the flange: It may be necessary to reinforce flanges made of non-metallic or brittle materials in order to prevent deformation or damage to the flange caused by uneven distribution of bolt forces. 4. Control the tightening force: During installation, accurately control the tightening force of the bolts to ensure even application of force, thereby avoiding localized overload on the flanges. 5. Use specially designed bolts or screws: Spring washers or other load-distributing devices can be used to help distribute the bolt load evenly. 6. Consult the design engineer or manufacturer: Seek advice from an engineer or manufacturer during design and installation to ensure that the connection method is safe and reliable. In practical work, such situations should be avoided, as mismatches in the flanges increase the risk of seal failure. If it must be done, professional help should be sought, and the operation must be carried out strictly in accordance with safety procedures and standards. .

Thank you, expert. May I ask where you found the information on the above measures?