Vertical-down progression, starting at the top and traveling down with the molten pool running just ahead. Travel is fast and heat input low, which suits thin-wall pipe, sheet metal and pipeline spreads running 6010 and other cellulosic rods. On thick sections or with slow travel it risks lack of fusion and cold lap, so many procedures restrict it.
Pipeliners run downhill, top to bottom in a couple of minutes a side, that's why the spread moves so fast.
Downhill is its own skill: welders trained only uphill tend to travel too slowly going down and roll cold metal over the root.
Also heard as
- vertical down
- vertical-down
- pipeline style
Related terms
Uphill
Welding vertically from the bottom up, which gives deeper fusion and more fill per pass.
6010
A deep-digging cellulosic stick rod run on DCEP, the classic choice for open-root pipe passes.
Cold lap
Shop term for weld metal that rolls over onto the base metal or a previous bead without fusing to it.
Lack of fusion
Weld metal that failed to fuse with the base metal or a previous pass at some boundary.