Now 6010 root (happy 7018 fill)- what rod sizes and types

I'll duck out at this point. I've way over-extended beyond my limited knowledge. I have a lot of hard work ahead of me first before I could possibly rejoin this conversation meaningfully.

I'm now a maths teacher in a vocational college, my learners being on engineering and trades courses. However, my effort over many years has been welding science and technology and I try to keep that portfolio alive. It's through welding that I got my current job...

I do get half a day a week to practice welding skills and will focus on pipe.

Regards and best wishes

Richard Smith

I got out of my depth here, relaying comment from people who have worked developing welding procedures for 690MPa / 100Ksi steel pipeline.

Richard S.

100ksi as-welded deposit is obtainable using 9010, a downhill pipeline rod for X-80 line pipe. Mid 90's ksi deposit is what you normally end up with using the most common downhill pipe rod in use today (70+). There are grades of line pipe that aren't suited to the normal consumables, but to take that still fairly uncommon example and then say that "celulosics don't match the strength of modern pipeline steels" is picking an unusual example from one extreem, and trying to make it apply across the board. Thousands of miles of pipeline (X-80 and below) are welded with these consumables (6010, 7010, 8010, 9010) in the U.S. every year.

JTMcC

Hi JTMcC

I apologise for going beyond my experience here. I've read all you have written with interest.

What I will do is to work hard with the xx10 series of rods. I've had a lot of discouragement here. Your information from "where it all happens" makes it clear that I should be a lot more robust about building these skills.

It is a realistic appraisal that I have recycled hearsay too much. I have though worked handling 690MPa / 100Ksi structural / pipeline steels from Dillinger Huette and Japanese steelmakers and studied weldability issues in a small project where I was sole researcher.

Richard Smith

I am able to comment that Lincoln Electric are very helpful and forthcoming, including directly from their UK base as well.

I have the book "Welding Pressure Pipelines & Piping Systems" as a PDF and will read and practice its recommendations very carefully.

Richard Smith

As a pipeline welder, I have an additional question to ask you:

After the root pass, is it common to grind the weld top bead, before the hot pass?

I get a very humped top bead, as I understand you expect if you drag the rod.

Further question leading from this:

"Feathering" the end of the previous weld run before striking an new rod - in reality is this frequently done?

I know of using a slitting blade spinning partly through the root gap to leave a "chisel edge profile" "feathered" edge which the next run can proceed from with an invisible progression.

Time is money. And so far I would have two angle grinders to hand, one with a normal grinding disc and one with a slitting disc...

Richard Smith

It's mandatory on any code work.

The tack welds are feathered, after that it's pretty uncommon.

I've known new guys that had just broken out that did that type of thing on tests. A full blown welder won't. When you start at a tack, or restart for a new rod, you start welding at least 1/2" before the end of the previous run, then by the time you get to the end of it and start putting in new bead it will tie in nicely without visible evedence that you started/stopped there.

More commonly you would have a grinder with a wire wheel, and one with a grinding disc. I keep a few thin wheels in my truck, but they only come out in unusual circumstances.

JTMcC.

Does it mention stringer beads on straight polarity using 6010?

JTMcC.

Yes - it mentions both -- Richard Smith

Hi JTMcC

Here is what it says in the booklet you mentioned - Lincoln's document "c2420.pdf", "Welding Pressure Pipelines & Piping Systems" (full credit for this direct quote given)

"Root Pass Welding In each case listed above, with the proper fit-up, the current with a 5/32'' (4mm) diameter electrode will be in the neighborhood of 130 amps. From this point, the current should be changed according to the individual welder's skill and needs. In the United States, root pass welding is usually done with reverse (DC+) polarity. In International locations straight polarity (DC-) is often used. Negative melts electrode faster then positive therefore travel speed should be faster and internal undercut and hollow bead defects are less likely. DC- (straight) polarity is also advisable for thin wall pipe to prevent burn through."

and later

"- Since reverse polarity (DC+) is commonly used by U.S. pipeline operators for root pass welding, switch to straight polarity (DC-) when burn through, internal undercut and hollow bead defects persist. Polarity change is an essential variable in API 1104 code - requiring a procedure qualification."

Continuing thanks and regards

Richard Smith

I'm glad you found that, you'd of never believed me otherwise ; ) I only comment on those parts of the wide and broad welding world that I have personal experience in, and there is a ton of missinformation out there. On the internet in general, and usenet in particular, there are people who hold forth as experts in areas they know nothing of, usually quoting straight out of the book and that's soooo easy to spot, especially in my main field as there is a small amount of information in print, so it's easy to recognize. Also the terminology is very distinct and unusual, making it even easier to spot people with no real world experience. So keep in mind that on usenet and the interweb there is no shortage of people spewing incorrect and just flat out wrong info. It really has to be seriously filtered to get down to the actual facts.

JTMcC.

Hi again JTMcC

You've got me wrong at least a little bit here.

Do put yourself in my position.

I turn my welding machine to DCEP and people come up to me and say "so you don't want weld penetration then?". Then someone buys a Dynasty

200DX and rings me on his cellphone, highly distressed, at the equivalent of 50c a minute trying to work out why Miller "make the machine cheaper by letting it switch the DCEP for stick" from DCEN for DC TIG when "with the right circuits it would stay on DCEN". Aaaggghhh.

It's dealing with these people - "third parties" to this conversation between us in the group - that I ask about evidence to show them - something incontrovertible. Now you point out about the Lincoln book, I must print it out.

As a scientist, of course I ask - is there data about burn rates, penetration depth, etc, where someone has set out and done a set of tests in controlled conditions. It's not that I disbelieve you - it's in my nature to look for a body of evidence.

BTW

I don't want to get onto a slippery slope or thin ice again, but was talking with some of the Welding and Joining Society folk today, meeting at the UK branch of Halliburton. They concur with what you were telling me, saying there is a resurgence of interest in using cellulosics, of the type you described - higher strength such as 8010 or 9010 - because the controllability of xx10 stick can dominate over the apparent productivity advantages of wire-feed processes. Now, I'm going to back away and go practice my welding, because I can't comment on this area myself...

Regards

Richard Smith

Just to be clear, I wasn't refering TO you, just a little warning that a lot of missinformation appears on the net, and on usenet in particular. So take it with a grain of salt.

JTMcC.