Overview of Taper Pipe NPT L1 Plug Gages


Taper pipe NPT L1 Plug Gage is a piece of versatile measuring equipment that is used to check the integrity of the internal threads to ensure they meet the required standard precisely. As a type of measuring tool, they need to be sourced from reliable manufacturers to ensure the accuracy of measurement every single time. Also called Go No-Go Plug Gages (more on this later), the engagement with the internally threaded part must be done with delicate force.

A Reliable Tool For Test:

As a hand-operated tool, you need to ensure a smooth engagement or you risk damaging the threads. Standard industry practice is to give the Taper pipe NPT L1 Plug Gage three revolutions while inspecting the threads of an object. For instance, if you are measuring the threads of a nut, use the Taper pipe NPT L1 Plug Gage and give it three complete rotations. If the threads are clean, you will find that it goes all the way. If it becomes jammed or stops, stop turning immediately as the threads of the nut have obstructions and hence failed the test.


Taper pipe NPT L1 Plug Gage is used by quality inspectors, manufacturing engineers, technicians, and machinists for the inspection of thread components and their precise calibration. They are an essential part of any quality control process to ensure the threaded components are made with the required calibration and are free of any obstruction.


Taper pipe NPT L1 Plug Gage are available in several types including:

  • Go Plug Gages – A hand-held single-ended gage that has a handle and pin, which is very precisely machined for accurate verification of the dimensional tolerance of a threaded hole. Go Plug Gages are offered with No-Go Plug gages as they are both used in combination to determine whether a hole falls under the acceptable limits or not. It helps in the testing of the “minimum dimensional limit” of a threaded hole which is the representation of the “maximum amount of remaining material on the part under inspection”. If a Go Plug Gage fits into a hole, it is acceptable, if not, then the piece must be discarded.
  • No Go-Plug Gage – It is used for the validation of the maximum dimensional limit of a threaded hole. This directly corresponds to the “minimum acceptable amount of remaining material” that should be on the part under inspection. If the No-Go Plug Gage doesn’t fit into the hole, it means that the hole diameter is “below” the acceptable limit. If it does fit, it means that the hole diameter is above the acceptable limit. The only acceptable condition is if Go Plug Gage fits and No-Go Plug Gage doesn’t fit.
  • Go No-Go Plug Gage – This is a combination of both Go Plug Gages with one on each side. It speeds up the inspection process and simplifies its use. The sides are either labelled or color-coded for their identification but the visual difference is also quite obvious.


  • A Taper pipe NPT L1 Plug Gage is simple and easy to use
  • A WESTport Taper pipe NPT L1 Plug Gage is marked with pitch diameter for easy identification
  • WESTport Taper pipe NPT L1 Plug Gage are available in a variety of metric sizes
  • A WESTport Taper pipe NPT L1 Plug Gage is highly accurate
  • WESTport Taper pipe NPT L1 Plug Gage ensures fast testing and ensures easy hand operation


WESTport Taper pipe NPT L1 Plug Gage is available in a variety of styles and over a wide range of measurements. WESTport stands proud as a manufacturer of quality assurance products with a commitment to client satisfaction and the provision of reliable products as an industry leader.

Written by WESTport Corporation. All rights reserved. Any reproduction is strictly prohibited.