This parallel edge results in the two pipes having offset center lines.
[1][2] Horizontal liquid reducers are always eccentric, with the flat side on the top, which prevents the build up of air bubbles in the system, (unless on control set, same as PV, TV, HV, LV) or in a pipe rack.
[3] Eccentric reducers are used at the suction side of pumps to ensure air does not accumulate in the pipe.
This offset configuration enables the eccentric reducer to maintain a consistent fluid level within the piping system, preventing air or gas accumulation.
[4] Horizontal gas reducers are always eccentric, bottom flat, which allows condensed water or oil to drain at low points.