- May 12, 2014
Vertical welding presents unique challenges
Ask even the most skilled welder what is the biggest challenge he or she faces in welding, and the answer is likely to be vertical welds. If we could defy gravity, we could eliminate the problem.
Industry suppliers Shop Metalworking Technology spoke with can't defy gravity, but they can provide advice about how to excel at producing a vertical up weld, whatever welding process you choose.
"The answer to how you improve vertical welds is like a spider web because different processes are affected by different factors," says Jay Ginder, senior applications engineer, ESAB North America, Hanover, PA. "Any changes you make to improve a vertical weld are influenced by the welding process you're using."
Welders who do nothing but vertical welds, especially critical welding for nuclear plants and ship hulls, for example, are sure to know the right techniques for creating the best vertical weld.
"The problem occurs with welders who typically do flat or horizontal welds and for smaller mom and pop shops that don't often perform vertical welds," says Mike Klegin, weld engineer with Miller Electric, Appleton, WI. "In these situations, they may struggle with selecting the right technique and the right consumables."
The biggest challenge with vertical welding, "no matter what process, is welding too hot or putting too much metal into the joint," says Kevin Beardsley, application engineer, Lincoln Electric Co., Cleveland, ON. "The bigger the molten ball of metal, the more challenges you're going to face welding vertically up or down."
Ken Alrick, part of the brand management team for welding at Victor Technologies, St. Louis, MO, says welders need to understand the basics of how different materials react with different welding processes.
"If an end user called me for advice about vertical welding I would ask them about the basics: what is it you're welding on, what is the contour of the part that needs to be welded, what is the certification you customer requires and then you decide on the right welding process for a vertical weld."
Watch the puddle
In welding, the puddle is like a crystal ball; watch it for signs of trouble and make adjustments to avoid the trouble.
"The puddle tells you everything," says Ginder. "If you're going too fast or too slow, or welding too hot or too cold; if the handle is too steep or not steep enough. The puddle will tell the welder what he needs to adjust, but if the welder doesn't understand how to weld vertically, it's a mute point."
Keep it cool
The key to a successful vertical weld lies in controlling the liquid weld puddle, and one of the best approaches is to select appropriate electrodes for different processes that can help to maintain the weld bead.
"When you're welding vertically, you're too liquid and the bead will sag and get clumpy in the middle and pull away from the sides, which causes undercut, and that is the tough part of vertically welding," explains Beardsley.
He advises selecting a process that is colder and less fluid. "With TIG and MIG, for example, weld on the cold end and not the hot end."
It's also important to select the right filler metal, adds Klegin. "To fight the effect of gravity, you need to control the weld puddle. Running a process that is cooler, like pulse MIG or TIG works, but you also have to select a filler metal where the slag freezes over the puddle, which helps hold the weld bead in place."
Do the weld match
A common problem among welders who don't typically perform vertical welds–some would arguably call it a shortcut–is using the incorrect electrode.
"There are electrodes designed to go vertical or only in the flat position, but you need to select the correct one for your process," advises Beardsley. "The biggest problem we encounter is welders using a slag type of consumable designed for flat welding in a vertical weld. People often try to use consumables in the wrong way and this can lead to weld problems."
While it seems like common sense, it's a good reminder for welders to keep in mind that different metals react differently, and in vertical up welds, the reactions are amplified.
"No matter what you weld, you need to achieve 100 per cent penetration and to do that, you need to match the filler to the base metal; that's the first step," says Alrick. "Then you consider the process you're going to use for the best vertical up weld, and that will depend, in part, on the industry standard and the item the welder is welding."
ESAB's Ginder adds "you have to consider how different metals transfer across the arc, how they carry the current, how they set up–fluid or stiff and sluggish. And you have to have knowledge about these alloys so you know where to set currents and how to protect the arc with proper gas coverage. There is so much involved; a lot of people think welding is not a technical skill, but it's extremely technical." SMT