Hints 5G Basic (7016/7018)

Hi everyone
Been trying to learn pipe welding. Basic (7016 root, 7018 hot-pass, fill and cap) on carbon-steel pipe - size around 6inch dia. Came by expert advice from nuclear industry workers when got a radiograph of an attempt at a 5G weld. Porosity around the weld showed that I hadn't even got a fluid weld-pool. So now know ignore what the Amps dial says and get the "fingernail" appearance of the weld pool kept clear under the arc and the following wall of slag doing the protecting (which I see doing 2G).
Not yet had chance to go try 5G again.
Anyway, anyone got any hints and tips for when I go try it? About how you set up the burn of the rod? About the prep? About manipulation? What should I be aiming for? Can you guys get around keeping the rod pointing straight to the centre of the pipe all the way around?
Rich Smith

  Quoted Text Here  
If you can have someone show you, it will shorten the learning curve. I used to weld half the root with one hand, then the other with my off (left) hand. I was amazed once I got good at it, because the touch on my left hand was a lot finer than my dominant hand, and I stuck less frequently, and less other problems as well.
Steve
visit my blog at http://cabgbypasssurgery.com

  Quoted Text Here  
Hi Steve, everyone
Another question - what size and thickness of pipe is recommended to practice on? Is my 10mm wall thickness 140mm dia (OD) pipe about right?
About handedness
I also quickly found that it is useful to be able to weld with left or right hand. And I also found that - well, I suddenly notice "hey,I'm welding left-handed and I didn't even think about it".
Richard Smith

  Quoted Text Here  
IIRC, and that screen is unavailable right now, a 6g test is 4 or 6 inch schedule 40 pipe, which would be near 10mm, which is close enough to 3/8" for that wrench and socket to be interchangeable.
Do you find you have a nice feel to your offhand when welding? I can't write worth a darn with my left hand, but it feels natural to weld with. I wonder why.
Steve
visit my blog at http://cabgbypasssurgery.com

  Quoted Text Here  
Steve - as I said, it came to me in a moment I was relaxed as the weld was running smoothly that I had the electrode holder in my left hand. I'd been concentrating on the access, the angles, the flow of the weld, ... I don't know why either -- Rich Smith

  Quoted Text Here  
It's going to make a big difference one day when you have a critical weld to make in a difficult place.
Steve
visit my blog at http://cabgbypasssurgery.com

  Quoted Text Here  
Exactly! Shortly after I got out of the shipyard's weld school with my first quals, I was told then shown by an old codger on the crew how much easier it was to weld some things left-handed. Ever since then I practice it whenever I can.
Since I've been off work due to my neck for over a year, when I came back I had to re-qual on all my material types and processes. It's been entertaining to run a bead on both sides of the joints (vertical-up), left- then right-handed. I even make it a point to swap torch/decay hands when tigging.
Now that my neck doesn't move as much as it used to, and I can't lay on my left hip (bone donor site), not caring which hand I have to use does make life much easier.

  Quoted Text Here  
I am not familiar with the use of 7016 for root pass. Do you have an approved procedure? does it specify DCRP or DCSP? In my area of the patch we normally use XX10 DCRP for root and hot pass work on black pipe.
My first pressure ticket did use a 7018 DCSP root on 1" plate. The root was much more difficult to perform than xx10 as any small eye blink could result in a loss of penetration, and the start-up after a rod change was tough to do and required a lot of prep to thin the stop and remove the warm up bead used to start before dropping into the root. The only time I ever saw this procedure required was for pre employment screening by a particular company which only used it as a means to refuse to pay top rate to most of their welders (who could not pass the root test). The only welder I knew who got the top rate working for this company passed his test by sneaking some xx10 into the test. The inspector said it was the best root he had ever seen which is a commentary on his inspection qualification because a xx10 root does not look anything like a DCSP xx18 one.
The pipe size you ask about is good as it is thick enough not to over heat quickly, and will require several passes to fill. Plan ahead as you want to leave just the right amount of space for the cap so that it will have just enough build-up but no more. You want to have a nice sharp edge on the groove so that you can just barely melt into it without leaving any undercut. Rod angle (and travel speed) is a matter of practice and position, you probably want to angle back a little at the starts and on the bottom and ahead a little between ~4 and ~3 o'clock and at the tie in on top. You need to watch the arc and see the fusion and the fill, and be able to see the temperature of the puddle and when it is about to freeze. You should know what the bead will look like before you remove the flux.
Good luck,

  Quoted Text Here  
Hi Private
Given that it is the person dabbling around trying to make my way talking to someone who is obviously the expert...
Anyway, it's an honour to try to answer your question as best I can.
7016 root pass - the story goes that "Filarc 56S" was dveloped orginally for makign North Sea oil-rigs. You run them DCEN (that's called "straight polarity" (DCSP) (?)). They seem to be optimised to run that way - they are happier on DCEN as much as 7018 is happier on DCEP.
xx10 is much easier to control - I find that and it leaps out at you by a long long way.
This is a conversation I've had with someone who has some experience from boilermaking (literally) and the oil industry.
He reckoned, on balance of advantages:
7016 root can work for you with structural tube, like an oil-rig.
On pipeline - you have the "laboratory testing" strength and high impact-energy of a Basic rod - but you have a far higher chance of incomplete-penetration defects. Giving you stress-raisers, corrosion-traps, etc, etc. So do you want a Cellulosic (xx10) root with lower strength and toughness which is a perfectly executed or better weld properties in the bit you do get but with penetration-bead-area defects? The person I was speaking with credited me with at least the sense to ask a good question......
He thinks that there's white-collar engineers who look up the properties in a book and decide they need those better properties - of the Basic root - without knowing the reality of doing the welds and what they will be like.
You've noted the words I used - "I asked", "someone told me", etc, etc.
Sneaking in rods of a different type:
Try 6mm (1/4") plate h-v T-fillet welds passing nick-break and macro-etch with criterion you must fuse away the terminating plate edge - using a 2.5mm (3/32nd") 6013 fillet-corner ("root") run :-( !!!!!!
Part of my recent development has been unlearning this **** we were taught in colleges here in the UK, where they had to devise ways to slow down students to keep the course costs low. In "commercial" tuition - you can only get what the rod wants to do - chose the correct rod, keep out of its way and help it do its job. That's a big "unlearning" compared to fighting rods trying to make them do what they are not meant to do of the college tuition.
The BC (Canada) welding course was very realisitic, as I saw it http://www.weldsmith.co.uk/tech/edn/0901_BCweldcourse_present/index.html I hope the same is true of US welding courses. Doing realistic welds with the real commercial welding rods.
Rich Smith

  Quoted Text Here  
I regard myself as a long way from an expert and would self describe as journeyman at best. My experience is mostly field work and I have never done any nuclear or super high tech work. I have done lots of oil patch and refinery work as well as general portable rig business.
  Quoted Text Here  
I do suspect that a low-hydrogen root is at least theoetically superior to xx10 and is the only choice for SS or high alloy if TIG is not available. A very high skill level is required to do good xx18 roots on pipe or plate and suspect that a properly executed xx10 root is vastly superior to a poorly completed one done with normally superior xx18 rod.
  Quoted Text Here  
There are more perfect welds made in the office than in the field. In the office it never rains, there is no wind and it is never freezing cold. The fitups are also always perfect and the right materials and support crews and machinery are always available.
  Quoted Text Here  
The only bad question is the one not asked, but answers and statements should always be passed throught the 'reasonability filter' and the 'authority and qualification tests'.
  Quoted Text Here  
I thought your report was well done but note that there is more to B.C. than the lower coast and not all of it is anything like the wet coast, some is even desert.
I would like to recommend the training and resource materials available from Lincoln Electric, particularly their printed books https://ssl.lincolnelectric.com/lincoln/apdirect/store.asp?P especially the Procedure Handbook https://ssl.lincolnelectric.com/lincoln/apdirect/item.asp?prodnum=PH and Metals and How to Weld Them https://ssl.lincolnelectric.com/lincoln/apdirect/item.asp?prodnum=MHW
For your interest in rigging I would also recommend http://www.oetio.com/store/hoisting-rigging-safety-manual.htm .pdf @ http://www.csao.org/images/pfiles/4_m035.pdf
Good luck,

  Quoted Text Here  
Thanks Private - good things to follow-up. Bit of good fortune for me - Lincoln UK is based here around Sheffield - reckon they have some Lincoln Foundation books.
Rigging - thanks - often feeling ploughing a very lone furrow there. Mainly it's the over-60's guys on site who I can talk with and get demonstrations of techniques from.
Rich Smith

  Quoted Text Here  
Private - thanks for those links. Questions I'd like to ask - will post a new thread if that's alright -- Richard Smith

Hi again everyone
Progress hopefully in rooting 5G - comment whether this sounds promising?
2.5mm 7016 (Filarc 56S) on DCEN.
My pipe looks to be 5inch sched80 (140mmOD, 10mm wall-thk).
Prep is 2mm root-gap, 2mm to 2.5mm root face
From 6o'clock to midday I can get around one side in 3 electrodes.
I am no longer reliant on the Amps setting, but report them as otherwise how would I describe my conditions?
In the lower sector I am at the maximum rating of the rod - which is 85A. So that's maximum burn with a hissing arc. (testing a higher current produced no useful result - between burn-through and lots of poorly keyed-in metal). Rod angle is a drag-angle to keep weld-pool clear of slag. Getting a "flat" penetration bead - in other words it's to the tube surface but no further.
Second middle sector drop to lowest current with mid-range burn at 75A reported on machine dial. That is the vertical-up sector. There is penetration bead. Rod angle is upwards push-angle to square-on to tube.
On the top sector current rises again to "split the difference" - reporting 80A on machine dial. Goes from push to drag angle of rod.
At all times:
Arc must play at least half on weld-pool (no useful result trying equivalent of cellulosic "keyhole"). Which means rod is weld-pool-thickness (should be thin) back from prep.
If prep. is locally wider, hold rod dead steady and build weld-pool up the middle. If it won't go, it won't go. Stop and change something - current? [While U-weave will keep weld going and looking just fine, rocking up and down the alternate side bevels, told don't do this, will get porosity. Not proven this - would be interesting to do test weld and radiograph...]
At all other times, gently jiggle the rod into the bottom of the prep - observe tiny shake of rod but it is not in any way a weave If it wont' pen, it won't pen. Should have slit prep groove open if it had contracted closer than it should be.
Rod angle is sole control of penetration(???). Pointing to tube centre gives maximum pen.???
There is some complex "falling forward" way of drawing the weld pool onwards - -in the same way that a person unbalances forward to start walking forward. Coming into view as conditions get more consistent, but vague impression so far. Certainly need to get going to avoid huge build-ups leading to burn-through. This aspect is about how you get a flat weld-bead top surface which does not need grinding. I am seeing some of these now.
I've described everything as much as I reckon it to be. It's a question - am I getting it right?
Thanks for all help.
Richard Smith