1st  Use quality tubes – give preference to  approved by INMETRO.
2nd  The clearance between the fittings and the pipes should be 0.15 to 0.20.
3rd  Sand the end of the tube and the inside of the connections  just causing scratches. Leave the residue caused by the sandpaper itself in place , as it contains aluminum oxide in its formulation.
4th  Pass a bead (360°) of Mega Pro in the sanded places (tubes + connections).
5th  Fit the tube to the connection. You will have  10 seconds  to position the part permanently.
6th  Keep the piece still so as not to interrupt the curing process.
7th  Clean, if necessary, the excess of product that remained externally, as there will be no drying. As Mega Pro is an anaerobic product,  its healing process only occurs in the absence of oxygen.