What are the precautions for welding small diameter pipes

1.Slagremoval. Carefully clean the slag at the included angle of the basemetal and the bottom weld on both sides of the groove, and the slagat the overlap of welding joints.

2.Carry out strip transportation at the position of 5-6 o'clock, thatis, after striking the arc at the overhead welding position, the longarc will preheat the overhead welding position. At this time, thefirst and second droplets will be thrown , away because of the poorfluidity and low temperature of the droplets. Then the droplet issent upward in a short arc and welded with,  crescent shaped strip ortransverse serrated strip. During the welding process, always keep ashort arc, pause for a moment when the welding rod swings to bothsides to make the transition , between the weld metal and the basemetal stable, and melt the edges on both sides of the groove for1-2mm to prevent undercut defects.

Duringwelding, the molten pool shall always be oval, bright, clear andconsistent in size. When the first half of the arc is closed, the arcpit shall be filled with some molten,  metal to make the arc pitslope, creating conditions for the welding , of the second half.Before welding the second half circle, the welding slag at thebeginning of the first half circle , shall be knocked off by 10-15mm,and the arc pit shall be filled at the end of the weld. When weldingthe covering layer with alkaline electrode, always preheat and weldwith short arc.

3.The electrode angle is that the bottom weld of the root has beenwelded, and the covering weld , has nothing to do with the rootpenetration. The main technical problem is that the covering weld iswell formed and the reinforcement meets the technical requirements.The material has a smooth transition and no undercut. The includedangle of the tangent line between the pipe and the welding rod in thewelding direction shall be about 5 ° larger than that of the primerwelding.