I can not find schedule 40 PVC pipe nipples in your catalog.

You will not find schedule 40 PVC pipe nipples anywhere! Threading of Schedule 40 plastic pipe is not permitted.

The wall thickness of Sch. 40 pipe is too thin, cutting threads into PVC pipe of this wall thickness reduces the structural strength of the pipe beyond a point at which it can be safely used in pressure application. Sch. 40 PVC pipe can only be installed by solvent welding and / or by using IPS (Iron Pipe Size) compression type fittings.

For this reason why schedule 40 pipe nipples are only available in stronger metal alloys such as carbon steel, 304 & 316 stainless steels, brass and red brass (bronze).

PVC nipples are only available in Sch. 80, the thicker wall of schedule 80 PVC pipe when threaded has a wall thickness which can be safely used in pressure applications. The use of extruded Sch. 80 PVC pipe nipples is recommended.

For more information visit the link at https://support.boshart.com/are-your-880-series-schedule-80-pvc-pipe-nipples-seamless