downhand vs uphill
downhand vs uphill
(OP)
I have asked the question "downhand vs uphill" progression on root,fill and cap passes,when welding pipe. Why do "pipeliners" run down and process and power piping welders progress uphill, what is the difference? No one seems to be able to help.
Can you please give me an explanation?
Sftyvlv
Can you please give me an explanation?
Sftyvlv





RE: downhand vs uphill
But to your real question of why and what's the difference - I am curious to see the reason as well and will wait for BigInch or Metengr to enlighten us.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: downhand vs uphill
Downhill also works good for seal welds....air casing,etc.
Always went by the old rule of thumb that a downhill is 7 times weaker then a uphill.
If you do sections and etch,one will see the difference.
Really depends on what you want in the end. You can always find some welder that can run any position with any rod, depends if the WPS allows and they can qualify.
RE: downhand vs uphill
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: downhand vs uphill
No problem. I have seen all kinds of things and yes to the downhill.
P5 root,7010 fill and cap all downhill. Been some places where the wind was so bad you could not use any Lo-Hy anyhow.
Back to the WPS and what the welder is qualified for. X-ray,bends. What does the job require?
If you want a answer run test coupons,section and etch. There will probably be some difference pulls between the up vs down.
RE: downhand vs uphill
Full penetration root beads are more readily made with EXX10 electrodes in the downhill direction largely because the welder can "push out or dress" the root pass with the hot pass because the root is thin (also see deanc's comment). When welding the root in the uphill direction with EXX10 electrodes the root cannot be similarly "dressed" because it is too thick. One problem regarding the thin weld deposit is root bead cracking when the hot pass is not performed very shortly after depositing the root pass or appropriate preheat has not been applied or a combination of both.
In the 1960's and early 1970's, it was not uncommon for root beads to be made with E6010 electrodes in the downhill direction in the process industry. In the early mid '70's a major oil company prohibited this practice, requiring all weld passes to be made uphill and this requirement soon became standard practice in the process industry.
In terms of weld completion rates, weld metal deposition rates are based on electrode diameter and current, not travel speed. It really doesn't matter which method of progression is used if the electrode diameter and amperage are essentially the same.
RE: downhand vs uphill
RE: downhand vs uphill
Vertical Down:
Low penetration
Concave bead
Slag
Problems with hot short materials
6G coupons don't qualify for Vertical Down (may have changed)
Vertical Up
Good penetration
Requires a little better technique
Better for poor fit ups and wide welds
RE: downhand vs uphill
deanc, pipeliners DO NOT run "final passes uphill". "Downhill 7 times weaker than uphill"???? please take a close look at the mechanicals of the downhill pipe rods, 6010's, 7010's, 8010's and 9010's in use.
Pipeline welding isn't 95% downhill, it's more like 100% downhill when using stick. Some dual shield procedures are being used on tie ins for automatic jobs and that of course is uphill. The flux core wire being used sometimes on automatic tie ins is a downhill wire.
deanc, P5 hasn't been made I'd guess in over 40 years.
The terms used in the pipeline industry are downhill and uphill. Downhand of course is a weld made on plate in the flat position.
Manually welded pipelines are welded downhill because of the speed factor.
Todays downhill pipe consumables (primarilly Lincoln's "Pipeliner" line) are pretty highly evolved and allow a lot of iron to be stacked in a short time, as I said the mechanicals speak for themselfs.
The pipeline construction industry is one where the question asked is "how many miles did you lay today", production is king. And it's an industry thats been around long enough that the process is pretty efficient.
This of course applies in the U.S. on mainline transmission lines. The related segments not generally considered pipelining such as oil field gathering system and town distribution system construction follows pretty closely the techniques and procedures used in mainline construction.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
unclesid,
There is no "vertical" in pipe welding (or overhead or flat for that matter), there is of course in plate. Pipe is welded either uphill or downhill progression.
We make full pen welds daily on pipe in downhill mode. Your reference to "low penetration" again applies to plate, 100% is 100% regardless of up or down.
Your reference to "concave bead", a concave cap is rejectable and cause for a weld repair on every job I've welded on. Convex caps are made all the time.
"slag"??? what about slag, trapped slag is a repair as well. And I don't have any idea what "6G coupons don't qualify for vertical down" means. I've taked well over 100 downhill pipe tests on a 45. That's pretty much a standard pipeline test along with a hand cut 12" on 12" inverted branch weld.
"Uphill requires a better technique"??? where do you guys come up with this stuff??!!
I've got 20+ years experience in both downhill and uphill pipe welding and that's just not true.
Shame on you guys putting out stuff you don't know or understand.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
I said 95%, you're right, it's probably more, but I have been on a couple of projects where Spie-Capag have wanted to do an uphill tie-in procedure, Chad-Cameroon was an example. They did some uphill tie-ins on some of their 480 kms.
But otherwise, if it's stick welding, it's all downhill, again as mentioned, because of speed. On the other Chad-Cameroon spread of 640 kms, there was not a single uphill weld made.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: downhand vs uphill
Could anyone give a metalurgical explanation as to which is a better weld (if in fact it is) and why its accepted in gas transmission lines and not in power and process piping using manual and semi auto welding processes -SMAW GMAW (thanks JT I should know uphill, downhill terminology).
Sftyvlv
RE: downhand vs uphill
That's why I made a point of saying my information applies to Mainline construction in the U.S.
I realize there are other parts of the world where different techniques are in use.
I'm always interested to learn what is being done across the globe in this field. Any info you're willing to give I'm happy to hear.
Regards,
JTMcC
www.firstratefabricators.com
RE: downhand vs uphill
www.kobelcowelding.com/PDF/handbook2004.pdf
RE: downhand vs uphill
I know pipeliners can weld sometimes but in my 42 years in and around pipe welding I've yet to see more that 20% walk in and pass a test. Far less if they were testing for CRAS.
I still standby my statements concerning the aforementioned weld processes. Though I will temper it somewhat by the fact most of my experience has been with in the power and chemical industry.
By the way the little "Red Rod" is still alive and weld.
RE: downhand vs uphill
Considering that every job is a test in my world, 100 tests in the span of 23 or so years isn't much, and considering that many jobs call for multiple tests (we worked for a particular gas company for several years that required like all gas companies retest every 6 months, that called for 8 tests every 6 months. That's of course 160 welding tests in the course of ten years. We've worked for dozens of gas companies so really my number is a bit low.
I only intend to correct missinformation on a topic we live and breath, not to threaten your supremecy of the interweb.
Every comment I've made is true and easily verifiable by anyone with an internet connection. You were wrong.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
As you state your experiences all I was doing was stating mine when it comes to welders and procedures. I'll concede that you have seen more welders come and go than I but I can pull up my records of around a thousand welders that worked for us over the last 20 years. These records give their pedigree and all qualifications along with all RT results or their period of employment. We require 100% RT on 80% of our piping.
By the way at my age bettering my image anywhere is the last of my problems.
RE: downhand vs uphill
Are we talking about Lincoln's Fleetweld 5P or was there another one called P5? Lincoln still makes Fleetweld 5P.
Good discussion and good example of people's differing perceptions based on their experience. I don't have any pipeline experience, only power experience. In the power industry, a EXX10 is only used downhill for root passes in low energy, low temperature systems, such as service water, fuel oil, coal or ash piping. With steam systems that have much higher pressure and temperature than pipelines, low hydrogen alloy steel electrodes are a necessity and they do not weld well with downhill progression.
RE: downhand vs uphill
Temperature is rarely a factor in cross country line pipe.
What pressure is your steam running at?
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
RE: downhand vs uphill
I'll have to beg to differ again. Pipeline work is all I do and I have never been on a project in the US where 80% of the welders bust out. In fact it is uncommon to have a pipeline welder come in for a test and break out, seldom happens.
I've been closer to that percentage in W. Africa when we had to use a certain % of natioanl welders, but these guys had no training.
I'll grant you pipeline welders for the most part are not B31.3 or .1 welders, nor can they really weld much of anything else (broad brush, don't want 798 to take offense) they have a very narrow skill set, but I have to say, in their field, they are good. And in my experience, in the States, I can recall a few projects only where a welder or 2 has busted out, for the most part it just doesn't happen.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: downhand vs uphill
I've never worked on power piping in the upper range you quote, how common is that? I haven't set foot in a powerhouse for a few years tho.
The new designation for 5P+ in the "pipeliner" line of consumable is 6P+. I have some samples but haven't seen it on the shelf yet. 5P doesn't see as much use these days as it used to but it's still the most user friendly consumable out there on the lower grades of pipe, in my opinion. 5P+/6P+ will be with us well after my grandchildren (yet to be born) are long gone ; )
Anyone interested in "as welded" mechanicals on downhill (or uphill) consumables can order, free, from Lincoln the information. Their "Stick Electrode Product Catalog", C2.10 and their "Pipeliner premium pipe welding consumables" C1.100 give quite a bit of information including charpies. The same is available on their various wires and cut consumables as well.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
798 runs the best welding school in the U.S. (my opinion of course, but right nevertheless) inclucing tig on exotics, uphill stick, flux core/dual shield, the bug, ect.
Pipeline work is the most cyclical of all construction and thousands of 798 hands work turnarounds and new construction several months each year. I don't think I've ever met a pipeliner that hasn't worked powerhouses/refineries. They would have years where the family would starve if they didn't.
Look at a few thousand pipeline films (or talk to those that have)and you'll see that they will typically make B31.3/1 requirements. B31.3/1 are many times used as the RT requirement on cross country line pipe and station work.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
But if you travel to cities with a large amount of refinery work, such as the east bay area, or during the days of nuke construction, or large scale steamer outages you'll find the rv parks and motel parking lots plumb full of 798 rigs.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
You have sparked a lively debate, my hats off to you. That's what the forum is about, exchanging ideas and experiences.
JTMcC
My apologies to the 798 gods (I live in Tulsa by the way), but you have to admit, these guys rarely bust out and for production welding you can't beat them.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: downhand vs uphill
RE: downhand vs uphill
I say, "but you really, really want to sometimes ; )"
unclesid, 798 is THE pipeliners union. There isn't another one.
Happy Memorial Day, fly that flag!
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
Nothing I like better then stirring up some welders,its at least twice as fun as poking Engs.
You must be fairly young, cuz if ya was old and crusty you would know to what I refered.
No problem,you are indeed correct in your posts. P5 is just a old phrase for 5P,slang if you like. Kinda like that 1109 rod.
So relax and reread your posts. The crews,for the most part do a great job these days and you are lucky you have the consumables you do.
So next time you test,I will watch for you. Maybe hover over your shoulder and ask you questions. thumbsup2
RE: downhand vs uphill
Just so you don't think I've no experience. Things have changed just a little since I got my withdrawal card.
RE: downhand vs uphill
But P5 is not a slang term for 5P among old timers because old timers remember and used the real P5. As I already mentioned, P5 was the predessor to 5P, a completely different rod, with a white coating.
It was replaced by 5P in the 1960's and was a nice improvement.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
This has evolved over the last few years to where more inside type work is being done downhill/cellulosic. Pumping station construction has for the most part switched over to DH. Ton's of Intel Fab piping is welded DH, to the point that some UA locals have had to run ads reqruiting DH welders.
Like has been said the necessary use of LoHi consumables pretty much means power piping will be UH progression. Tho Lincoln does make a downhill low hydrogen rod.
More inside applications are going to DH bead and hot pass with LoHi fill and cap because the joint requires less filler. Pipe spacing is tighter when runnin the bead DH, leaving less to fill and cap. That, plus the bead/hot pass go in quicker DH.
So the lines today aren't drawn as sharply as in years past.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
There is no real metallurgical difference in welds made uphill or downhill using the same EXX10 classification electrodes. The only metallurgical reason to weld uphill with EXX10 is somehat superior resistnce to hydrogen cracking in the root and this can be readily compensated for when welding typical pipeline wall thicknesses.
There are a number of reasons to use uphill low hydrogen electrodes and other low hydrogen welding processes. Superior impact toughness is but one. High energy pipe in the process and power industry is often quite thick compared to pipe used for pipelines. The joint restraint and three dimensional cooling of the thicker wall pipe, not to mention hardenable low alloy steel pipe also welded, produce metallurgical structures highly susceptible to hydrogen cracking and hydrogen cracking was not uncommon in thicker welds when made with non-low hydrogen processes. Properly made welds with low hydrogen electrodes also provide superior radiographic quality. Note that slow speed fine grain films (more sensitive) are most often used in the process and power industries while high speed films were predominantly used in pipelining (again productivity being paramount).
RE: downhand vs uphill
Using 8P+ (the new and improved 70+) you'll see these numbers: Yield strength in the low 80,000's, tensile in the high 90,000's, elongation in the upper 20's, and charpies in the upper 70's @ -20F and lower 60's @ -50F.
Diffusable hydrogen in multi pass downhill with these rods will be about what you'd see in a single pass LoHi weld, certainly not the levels achievable with LoHi of course but better than most people expect.
I'd just love to see some info to back the claim made that the rule of thumb is that DH progression is 7 times weaker than UH.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
Where did you get your engineering degree?
rmw
RE: downhand vs uphill
We work with engineering on a regular basis and employ engineers from time to time. I have of course an abiding interest in that engineering which affects our work.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
Please don't answer rmw. This forum could go on indefinitely, when the "football wars" get started.
And, thanks for sharing your wealth of experience. Sometimes when I'm outside of my field, I can't tell when I'm reading BS or not. Your posts are refreshing and, for me, what this forum should be about: Engineering Tips ("Tips" meaning "from firsthand experience").
S. Bush
www.water-eg.com
RE: downhand vs uphill
Got it. I saw it coming, I'm done.
JTMcC.
www.firstratefabricators.com
RE: downhand vs uphill
Some of the new hybrid short arc methods (STT and RMD) use a vert down root progression. I expect this is for speed but wonder if distortion is something important, perhaps this aids in getting a quick and perhaps cooler pass in there?
Thanks for any input.
RE: downhand vs uphill