3/8"-18 NPT thread tap

3/8"-18 NPT thread tap is used to cut internal tapered NPT pipe threads in drilled holes. It is typically used for threaded connections where fittings, sensors, adapters or other components with 3/8" NPT thread need to be installed.

3/8" indicates the nominal NPT pipe thread size, while 18 means 18 threads per inch. NPT is a tapered thread that tightens the further it is screwed in.

NPT sizes are based on old pipe measurements, so the actual thread diameter is larger.