The liner on the valve’s flange face creates a raised face which can vary from 2.5mm (0.098”) to 4mm (0.157”) high. This raised face will cause bending and probable breakage of the FRP flange. If extremely low bolt torque is used to minimize flange bending, the gasket being compressed will not seal. To minimize flange bending it is common to put a gasket spacer around the outside diameter of the valve’s liner to affect a flat face and eliminate flange bending. The variation of the valve’s liner height complicated making a surface that would seal since a standard 1.6mm (0.063”) gasket spacer could be short and a 3.2mm (0.125”) spacer would be too high.