How to tighten pipe flange bolts?
Final torque for the pipe flange bolts is dependent on the type of gasket used. This torque provides the clamp load on the gasket needed for proper sealing. Metallic and spiral type gaskets require greater clamping force than flat rubber gasket material. Higher system pressures lead to increased fastener torques. Pipe flange gaskets are never be used to pull the piping up to the pump. This can stretch the bolt, bend a pipe flange, break the pump casting or bend a suction plate. Rather, pipe flange bolts can fill the gap between the pump and spool piece by using the correct tightening sequence. Pipe flange bolts should be tightened in the correct sequences as illustrated below.