Press Fittings and Valves: How to Detect Leaks

Written by Ashley Petersen 2016-10-25

NIBCO® Press System® ½” – 2” fittings and ball valves have been re-designed to include a special feature which allows a connection to leak if it has not been crimped. A uniquely designed EPDM o-ring allows fluids or gases to flow past the seal and leak when the fitting or valve has not been pressed. When the fitting or valve has been pressed, the o-ring will create a water tight seal around the tube.

This installation video demonstrates how to test with this new feature, and how to identify and correct a joint that has been left un-pressed.


Before beginning, review the testing instructions for fittings and valves with leak detection, found in the installation section of the NIBCO Press System catalog.

Testing the System with Air

  • Set up the required air pressure equipment to be able to test the system.

  • Next, pressurize the system up to 15 psi maximum using dry, oil free Press Fittingscompressed air, carbon dioxide, or nitrogen.

  • Allow the system pressure to stabilize for a minimum of 2 hours.

  • If the system pressure has dropped, add more air to bring the entire system up to 15 psi maximum. If the system pressure increases above 15 psi, bleed off the excess pressure to ensure that the system is at a maximum pressure of 15 psi.


Finding an Un-Pressed Joint (Air)

  • If the system pressure continues to drop, inspect all joints for un-pressed fittings. 

  • First, visually check for any un-pressed joints.Press Fittings

  • If there is an un-pressed joint at this pressure level, depending on the background noise at the jobsite, it is often possible to hear the air coming from the un-pressed joint.

  • Another way to find an un-pressed joint, is to check all press joints for air leaks using a commercially available leak test solution or a soap and water mixture.

  • If a leak is found, and the joint is determined to be un-pressed, turn off the air pressure before crimping the joint. Make sure that the tube is inserted fully into the fitting or valve and crimp the joint with the proper tool and jaw.

  • Once the system has been confirmed to be leak free, pressure can be increased to the recommended working pressure to verify system integrity.


Testing the System with Water

  • Set up the required water testing and pressure equipment to be able to test the system.Press Fittings
  • Next, pressurize the system up to 50 psi maximum using potable water.

  • Allow the system pressure to stabilize for a minimum of 2 hours.

  • If the system pressure has dropped, add more water to bring the entire system up to 50 psi maximum. If the system pressure increases above 50 psi, bleed off the excess pressure to ensure that the system is at a maximum pressure of 50 psi.


Finding an Un-Pressed Joint (Water)

  • If the system pressure continues to drop, inspect all joints for un-pressed fittings. Press FittingsThe NIBCO Press System fittings with the leak detection feature are designed to leak in an un-pressed condition.

  • Check all press joints for leaking water.

  • If there is an un-pressed joint at this pressure level, it will be easy to see the water spraying or dripping from the un-pressed joint.

  • If a leak is found, and the joint is determined to be un-pressed, turn off the water supply before crimping the joint. Make sure that the tube is inserted fully into the fitting or valve and crimp the joint with the proper tool and jaw.

  • Once the system has been confirmed to be leak free, pressure can be increased to the recommended working pressure to verify system integrity.

In general, once the system has been checked for un-pressed joints, always test the NIBCO® Press System in accordance with normal practice and to local jurisdiction piping code.


The NIBCO Press System is a safe, easy and fast way to install a copper piping system, and is backed by a name you can trust. For more information, download our Press System Quick Reference Guide!

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