What kind of welding process is this?

This is oxyacetylene welding, which is copper brazing. The professional name is fusion welding.

Also known as brazing, it requires oxygen and acetylene gas, and then a special welding torch.

H0 1- 12 welding torch

Heat the workpiece with the flame of the welding torch, preheat it, bake the copper-clad covered electrode almost on the fireworks, and stick some brazing powder (copper flux).

Then put it on the weld where the workpiece needs to be welded to melt. This requires skilled craftsmanship. If the temperature is low, copper and covered electrode cannot be melted. If the temperature is high, a thin tube will melt and leak.

It also needs to be operated under the guidance of a professional master. The captain must have a special operation certificate, and can't work without a license. This is illegal.

Apprentices are not allowed to operate independently.