Universal fittings and PE to copper compression fittings, simple, compact, efficient! Universal fittings, installation: Chamfer the pipe end. Mark the pipe portion to be inserted into the fitting. Unscrew the fitting and twist the pipe through the fitting, up to the pipe stop. Tighten the nut firmly, use a wrench for final tightening. PE to copper compression fittings, installation: Chamfer the copper pipe end. Mark the pipe portion to be inserted into the fitting. Unscrew the fitting and twist the copper pipe through the fitting, up to the pipe stop. Tighten the pipe firmly, use a wrench for final tightening.