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San Diego | Orange Fluid System Technologies

Your Authorized Swagelok Product and Service Center

Gap inspection Gauge

Swagelok tube fittings can only perform at a high level of leak resistance if they are properly installed. We are happy to work with your team to ensure that they understand the proper steps to effective installation. One way to verify that your fittings have been properly tightened is with a tool called a gap inspection gauge. Learn more in the video below.


To test fitting assembly using the gauge, line it up with the gap between the nut and the body, then gently push it into the gap.

  1. If the gap is too small for the gauge to enter, the fitting has been properly tightened.
  2. If the gauge can fit into the gap, more tightening is needed.

Gap inspection gauges come in different sizes, so make sure the gauge is appropriate for the fitting size. You can review available sizes here 



Note: Gap inspection gauges are not able to measure re-assembled fittings or if the fitting was over-tightened in the first place. Over-tightening can stress the fitting and reduce its life. 
San Diego Fluid System Technologies offers monthly classes that teach you how to avoid over-tightening and a variety of similar best practices on proper tube fitting installation. Check out the Tube Fitting Essentials class information and see why the half day investment in your team is worth it.