Press-Connect Joints for HVACR Applications

Advances in press-connect and O-ring material technology are now such that press-connect joining can be utilized for high pressure HVACR applications.

Press-connect joints for high-pressure HVACR applications require the use of a completely different type of press jaw configuration. Press-connect joints for lower pressure plumbing, process-piping and many non-medical grade compressed gases utilize a single standard hexagonal press (SHP) pressing pattern. Whereas press-connect joining for higher HVACR pressures, rated up to 700 psi (see Table 14.4b), require the use of specially designed press fittings and crimping jaws to provide a 360° double crimping of the fitting (Figure 11.17).

hvacr cpompleted jointFigure 11.17. Completed joint showing double 360° crimps

Preparation of the tube ends and deburring of the I.D. and O.D. remain the same as that described in the previous installaiton steps. However, there are a few critical steps that need to be taken to ensure compliance with the fitting manufacturers' minimum installation requirements.

Full depth of insertion into the fitting shall be clearly marked prior to inserting the tube into the fitting (Figure 11.18).

tube marked for insertion into hvacr fittingFigure 11.18. Tube marked for insertion into HVACR fitting

Crimping jaw choice and jaw placement prior to crimping are the same as described previously.

Once the pressing process has been completed the jaws can be removed from the fitting and visual examination of the final pressed fitting shall be performed. It is imperative that the tube has remained fully inserted after the pressing process (Figure 11.19).

hvacr completed jointFigure 11.19. Completed joint with insertion marks visible

The completed double 360° crimp shall be inspected for the appropriate crimp mark as prescribed by the fitting manufacturer (Figure 11.20).

hvacr visible press markFigure 11.20. Press jaw crimp mark

The crimp locations shall be checked with the go-no-go gage, provided in the pressing kit, to ensure the press process has been completed correctly (Figure 11.21, 11.22, 11.23).

hvacr go_no_go gageFigure 11.21. Go-no-go gage
hvacr uncrimped fitting - GNG gageFigure 11.22. Un-crimped or improperly crimped fitting
hvacr fitting correctly crimpedFigure 11.23. Correctly crimped fitting