Tube ends shall be inserted into the socket, either fully or to a mechanically limited depth that is not less than the minimum
cup depth (overlap) specified by ASME B16.50. [NFPA 99:5.1.10.4.6.1]
Where flux is permitted, the joint shall be heated slowly until the flux has liquefied. After flux is liquefied, or where flux is not permitted to be used, the joint shall be heated quickly to the brazing temperature, taking care not to overheat the joint. [NFPA 99:5.1.10.4.6.2, 5.1.10.4.6.3]