Under the welded pipe from the top of the arc, from top to bottom all-position welding technique, the method of welding speed, weld appearance, good welding quality, you can save welding materials, reduce labor intensity, which is a common SMAW can not be compared and now more widely used in large-caliber long-distance pipeline welding in all position of power in the construction of low-welded large diameter thin-walled tube has some promotional value. 

Under the welding usually select the appropriate welding current, electrode angle and welding speed, straight through drag down or suppress arcing swing slightly to finish welding. Ordinary electrode prone drip drip molten iron and slag under question, and the use of the pipeline dedicated to welding electrodes, welding specifications strictly enforced, you can solve these problems. Cellulose type electrode welding slag less, arc force, stiffness enough to prevent the molten slag and drip down and penetrating arc large, especially for thick-walled containers and welded steel pipe hit the bottom, you can eliminating the root shovel operation, thereby improving work efficiency, improve working conditions, but because of its high hydrogen content of the weld, so for domestic high-pressure pipe welding current commonly used cellulose electrode backing plus low hydrogen electrodes and filler cap surface welding. 

The right set of tubes and tack welding is on ensuring the quality of the welding, the back of a good weld is an important factor. Tack welding seam is part of a formal, not only requires forming side welding, but also to ensure the welding quality. Tack welding length 20mm, a thickness of about 3mm, gentle slopes on both sides of the weld should be ground into shape, in order to facilitate joint. 

Next to the welding electrode is very important to use the correct angle. Backing weld, filling and capping rod angle is basically the same, but the arc length and transport of a different form. Next to the weld, the weld is controlled by the length and width of the main forms of transportation of the arc, arc and arc close attention to the wrong location should open.