Tube flaring can take place in two different ways:
Tube to be single flared if walls are sufficiently thick.
Tube to be double flared if walls are too thin.
Since a proper sealing depends to a great extent on the flaring operation, compliance to some basic rules is of the utmost importance.
Tube material has to be of quality such not to exfoliate or crack on the inside of the cone when flared.
Generally good results are obtained on tube steels having an elongation of min 21%. The tube cutting is to be perpendicular to its axis.
Tube straight portion has to be sufficient to allow a correct positioning on the flaring machine using standard tooling. Usually the straight portion ranges from 38 to 50 mm. For better flaring results comply with dimensions given in the table on the right.