Pipe Thread Plug Gages - NPT- NPTF - ANPT - Hardened Steel

Gages Made to ANSI/ASME B1.20.1 1983

NPT (National Pipe Thread) plug gages are essential tools for inspecting the quality of threaded pipe fittings. Each type serves a specific purpose in the inspection process. Let's break down the differences between L1 Basic, L3 Basic, and 6-Step Crest Check NPT plug gages:   

L1 Basic Plug Gage:

• Purpose: Primarily checks the pitch diameter of the thread at the hand-tight length of engagement (L1).  
  Focus: Ensures the thread is within tolerance for proper mating and sealing.

L3 Basic Plug Gage:

• Purpose: Checks the taper and overall thread profile at the wrench-tight length of engagement (L3).  
• Focus: Verifies that the thread has the correct taper and extends to the required length.

6-Step Crest Check Plug Gage:

• Purpose: Inspects the truncation limits and taper of the minor diameter.
• Focus: Assesses the sharpness of the thread crests and the consistency of the taper.