After removing surface oxides, what should be the next step in the preparation process?

In the preparation process for silver brazing, after removing surface oxides, the next crucial step is to round the pipe end with an expander. This is important because a properly rounded end enhances the fit of the joint, ensuring that the surfaces to be joined make good contact. This contact is essential for effective heat transfer during the brazing process and for achieving a reliable joint.

Properly rounded ends also allow the filler metal to flow smoothly into the joint when heated, helping to create a strong bond. If the ends of the pipes were not properly rounded, there could be gaps or misalignments which could lead to a weak joint upon cooling.

It's important to also consider that checking for even clearance or sizing pipes has a role in the overall process, but these steps typically follow the preparation of the joint surfaces, such as rounding the ends. Flux application is usually considered after ensuring that the pipe ends are adequately prepared and fitted, as flux will help in preventing oxidation during the heating process. Therefore, rounding the pipe ends with an expander is the logical next step after removing surface oxides.