Spatter hazards in galvanized pipe welding

The damage of welding spatter of Large diameter hot-dipped rectangular galvanized pipe is manifested in the following aspects: decreasing Welding Deposit power and decreasing welding productivity; splash easily adheres to welding parts and nozzles, affecting welding quality, worsening welding working conditions and adding finishing time; unstable welding pool, resulting in rough weld shape and other shortcomings.

　　To avoid splashing, we should pay attention to five points:

　　1.In galvanized pipe arc welding, there are certain rules between the spatter rate and welding current of each diameter wire: the spatter rate is smaller in small current zone, smaller in large current zone, and larger in central zone. Therefore, when selecting welding current, the current area with high splash rate should be avoided as far as possible.

　　2. the length of the welding wire should be shortened as much as possible, so that the welding spatter of the galvanized pipe can be reduced more effectively.

　　3. When gas maintenance welding machine chooses positive polarity, because the arc is affected by the anode mottling pressure, the spatter increases sharply and the galvanized pipe size is large, so the DC reverse polarity connection is generally used.

　　4.a large inductance is connected in the welding loop. In gas maintenance welding with medium current specification, because of the short arc length and the continuous movement of droplets and pools, droplets and pools are prone to short-circuit, so besides the large droplet extrusion transition, some droplets are short-circuit transition, and a larger inductance is connected in series in the welding circuit to make short-circuit electricity. The flow rises slowly, so that the welding spatter of the galvanized pipe can be properly reduced.

　　5.when the welding torch is directly welded to the galvanized pipe, the amount of spatter is less, and the larger the squint point is, the more spatter will be. It has been proved by practice that the forward or backward tilt of the welding torch should not exceed 20 degrees, and can not exceed 25 degrees.