Friction between the bolt, nut and the flange surface is a force often overlooked during gasketed joint assembly. When determining the torque required to properly tighten the bolts, a nut factor or friction factor needs to be taken into consideration. Using well lubricated nuts, bolts, and nut and bolt faces can help control the frictional load losses during assembly. 

It is very important to lubricate the flange bolts, during the installation process. Ensure your bolts are greased sufficiently with Molykote® G-Rapid Plus (or similar lubrication if special requirements) so that all threads and contact surfaces between nuts and flanges are covered with the correct lubrication.

Failure to sufficiently lubricate flange bolts may result in an increase of required bolt torque by as much as 400%. Consequently, this may result in damage to the flange bolts and also runs the risk of installing the gasket with insufficient gasket stress, enabling the risk of leakage.

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