Alpha Thread Gage - Pipe Thread Gages


In gaging internal threads, either ANPT or NPTF, there are three gaging members involved: L-1 thread plug which checks the thread elements within hand pressure engagements. L-3 thread plug which checks the threads that will be engaged under wrench pressure. 6-Step plain plug which is used to check the minor diameter of the female fitting. In gaging, the relation of the steps on the L-1 and L-3 plugs and the plain taper plug to the product should not vary by more than one-half turn.

FOR GAGING EXTERNAL THREADS-ANPT or NPTF
external


n gaging external threads, either ANPT or NPTF, there are three more gages employed: 6-step plain ring which checks the major diameter of the male fitting. L-1 (thin) ring which checks the the thread elements over the distance of hand pressure engagement. L-2 (thick) ring which checks the the thread elements of those threads engaged under wrench pressure. When inspecting external threads with these gages, the size indicated by each gage should not vary by more than one-half turn from that of either of the other gages.

ANPT and NPTF Gages are NOT interchangeable.

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REFERENCE SHEET	Reference Sheets Available >Pipe Thread Gages- Illustrated • Internal & External Threads Illustrated

PIPE THREAD GAGES

FOR GAGING INTERNAL THREADS-ANPT or NPTF
internal