Dear all
If one considers welding processes like SMAW, GTAW, GMAW and FCAW in the vertical position. When do you use uphill progression and when downhill progression? And what are the pros and cons of the uphill and downhill progression? Thanks
Hi
Downhill progression is almost always used for speed. When welding uphill, you are "fighting" gravity, so your speed is slow. When welding downhill, gravity pulls the weld pool down, so it results in great speed. Vertical down welding is quite difficult at the best of times, and many welding consumables and welding parameters will not allow downhill welding. The big cons of downhill is that if you do not keep control of the weld puddle, you will end up with slag inclusions and lack of fusion defects.
I am sure that other will be able to add to this reply.
Regards
Niekie
Typically uphill is regarded as more suitable for higher pressures. You see downill on lower pressure stuff and yes if speed is a factor then downhill is faster.
By vagabond 
Date 03-01-2012 13:33
Edited 03-01-2012 13:37
The pro's and cons vary widely depending on process. You listed a number of processes so I would suggest deciding on the process first as they also each have their pro's and cons. If you are going downhill you will likely use either an SMAW or FCAW and maybe GMAW. I have never seen GTAW ran downhill in a qualified procedure. . . .it can and is done. But I've never seen a procedure for downhand only for GTAW and I can't see why you would want one personally. Whether or not it is field/shop welding would be my biggest question. Most welders cannot get repeatable good results in a field situation with GMAW and FCAW. These are shop only methods in my book. Just my .02. Take it for what it's worth.
Hi
A lot of high pressure piping is welded with the downhill progression. In the case of GMAW, this is mostly done with automated processes, and is very sensitive to even small changes in welding parameters. A lot of automated GMAW on pipelines is done "in the field" in the downhill progression.
Regards
Niekie
Not trying to be ugly here..
Buy a textbook!
Your question is GIGANTIC :)
To properly answer your question for each process would take pages.
Just with SMAW we have four different F#'s and how they penetrate with different polarities both up and downhill... Sheet vs plate,, fillet vs groove,,,, Do we want maximum penetration? do we want minimum?
If your curious about a single process or transfer move (GMAW) and the relative merits of welding uphill or downhill... That we can tackle in a single post. :)
There are five F numbers for SMAW. Don't forget F5 for heat and corrosion resistant covered electrodes.
Best regards- Al
As stated by Lawrence above, that is a huge question.
In the most general terms, using downhill it is usually vastly easier for a poorly skilled welder to achieve a reasonable visual appearance. Downhill it also is usually easier to achieve various internal / fusion type discontinuities.
Firefly,
It also depends to which code you are working to …
D1.1 – 2006
3.7.1 Vertical-Up Welding Requirements.
The progression for all passes in vertical position welding shall be upward, with the following exceptions:
(1) Undercut may be repaired vertically downwards when preheat is in conformance with Table 3.2, but not lower than 70°F [20°C].
(2) When tubular products are welded, the progression of vertical welding may be upwards or downwards, but only in the direction(s) for which the welder is qualified.
Cheers,
jb
