How Should Galvanized Pipes Be Welded

Galvanized pipes are corrosion-resistant, have a long service life, and are relatively inexpensive, so they are widely used. When welding galvanized pipes, we should pay attention to the correct welding method and some precautions:
1. Before welding
The pre welding preparation of galvanized steel is similar to that of ordinary low-carbon steel, mainly by processing the groove size and the nearby galvanized layer. The groove size is generally 60-65 °, leaving a certain gap, usually 1.5-2.5mm; Before welding, in order to reduce the penetration of zinc into the weld seam, the galvanized layer inside the groove should be removed before welding.
2. During welding
The welding method adopts centralized chamfering without leaving blunt edges for centralized control. The two-layer welding process reduces the possibility of incomplete penetration. During welding, attention should also be paid to:
(1) When welding the first layer of multi-layer welding, try to melt the zinc layer and vaporize and evaporate it to escape from the weld, which can greatly reduce the amount of liquid zinc left in the weld.
(2) When welding fillet welds, try to melt and vaporize the zinc layer in the first layer to escape from the weld seam. The method is to first move the end of the welding rod forward by about 5-7mm, and then return to its original position to continue welding forward after melting the zinc layer.
(3) When welding horizontally and vertically, it is recommended to use short slag welding rods such as J427, as this will reduce the tendency for undercutting; Adopting the technique of back and forth transportation, the welding quality is better.
3. After welding
After welding, the galvanized layer at the welding point of the galvanized pipe must be polished off, otherwise problems such as bubbles, sand holes, and false welding may occur, and the weld seam may become brittle and the rigidity may decrease.