There are many cases where a serviceman needs to make a soldered

or brazed joint between two tubes; one tube which fits rather loosely inside the other.

Good practice demands that the tubes be as close as .003 in. to each other. Fig. 2-19 shows a special tool used to constrict the outer tube until it fits the OD of the inner tube. Using this tool the serviceman can easily solder or braze the joint without danger of leaks or of flux getting into the system,