This welding technique uses a filling material which has a lower melting point than the base material. The benefit of this technique is its ability to obtain a tight sealing by modifying or deforming the base material as little as possible. This weld allows joining together even mixed materials.
The joint must be designed so that it ensures a suitable support, while the filler material is applied by capillary action. Depending on the requirements of the finished product, a flame burning either oxy-acetylene or hydrogen is used.