Worm Track problems

By ssbn727 (*****)

Date 01-17-2004 10:56

Hi New Guy!

Welcome to the forum!!! I need to get more details from you before I or anyone else for that matter can offer any suggestions to eliminate your problem so, here goes...
1)This job - is it being done in the shop or in the field?
2)What's the average distance from the work to the contact tip or better yet, the gas cup?
3)How far in or recessed is the contact tip from the edge of the gas cup?
4)How many Cubic feet per hour is your gas flow rate setting on your flow meter?
5)Why so hot preheat and interpass temps for 4" schedule what pipe and/or what is the wall thicknesses of both grades of pipe?
6)Why so much of a variation in the current/voltage range being used by your welders and do you know what are the IPM's(Inches Per Minutes)settings on the wire feeders by any chance?
7)What code are you working from, AWS, ASME?
8)Are you working off a WPS and do you have PQR's for every welder?
9)Did you already test or qualify these variables with any other shielding gas mixes and/or filler wire?
10)What brand may I ask are you using for the filler wire?
11)Are you performing PWHT?
12)What NDT methods are being used for inspection? Just curious...

Now, I know these are alot of questions and some of them may or may not be so relevant to your problem but; I had to ask them because of the nature of the material you're using and all of the variables you've provided us so far - forgive me if I'm prying too much!
This website below has a wealth of info that I'm sure you'll find interesting and I strongly encourage you to at least check out the educational material available (Money well spent if buy them!!!) also because it reads as if you have a weld process controls problem on your hands. Ed Craig will set you straight so, here it is:
http://www.weldreality.com

Remember, there is alot of info there so take your time checking out all of the links in Ed's website. You mentioned that you have more than one welder under you, then do'nt hesitate any longer and BUY the books and video Ed has got for sale in his site because the educational material will transform your situation, provide weld process training to you and your welders!!! Btw, I already posted your question to Ed so, I should be getting a response from him shortly and I'll relay any suggestions to you as soon as I hear from him.
I look foward to your response.
Respectfully,

SSBN727 Run Silent... Run Deep!!!

By Niekie3 (***)

Date 01-17-2004 12:14

Hi newguy

Worm tracks are a result of gas bubbles that move through the weld metal while it is in the "mushy stage". This is typically caused by a combination of two factors:

1) Too much gas being evolved in the weld metal.
2) Welding with such parameters that the weld puddle is not fluid enough.

When I look at your welding parameters given, I notice that the voltage range is close to that required for spray transfer. (The 29V at any rate.) I suspect that you really want to weld in dip transfer, because the piping would probably be welded out of position. In addition, the gas you are using is typically used for dip transfer.

It may be that due to the high voltage, the welders are trying all kinds of tricks to get a suitable weld puddle, which may include welding at a much too low amperage.

I suggest that you bring your volts down to the 18 - 20V range and let the welders adjust the amperage to suit. In addition, make sure that the consumables used are not wet or in any other way contaminated. Also make sure that the gas flow rates are not too high. As you are getting this problem with a number of different welders, contaminated gas is probably not the root of your problems, because they will surely all have their own gas bottles. Having said this, it may be that you got an entire batch of defective gas, so it may be worth your while to check this out.

I would however start with getting my parameters optimised for dip transfer, and then working from there if the problem persists.

Regards
Niekie Jooste
Fabristruct Solutions

By GRoberts (***)

Date 01-17-2004 18:47

As Niekie pointed out, the worm tracks are gas trying to escape the weld. I would differ with him on the volts and amp advice he gave though. It looks like Niekie was referring to solid wire with GMAW, but you are using flux core welding with mixed gas and a T1 electrode, so depending on the flux, you will either be in globular or spray transfer. I don't see anything glaring with the parameters you posted, so I think it would have to come down to welder technique, or material problems. When I have seen worm tracks, the greatest cause is usually inadequate sheilding due to incorrect gas flow rates, clogged nozzles, or bad torch angles/technique. Since you are welding returns and may be in hard to access places, you might want to look at the torch angles. It is easier to get bad shielding on the cap pass as there are no longer any groove walls to help keep the shielding gas around the weld. Also check your flux core wire. Is is relatively new, or has it been sitting around for a while? Flux core wire won't absorb moisture as fast as stick electrodes, but will if exposed too long. This can cause worm tracks too.

By rodofgod (**)

Date 01-18-2004 01:41

Check your welders 'stick-out; lengths! We had this problem and the answer was down to welding voltage!

By Niekie3 (***)

Date 01-19-2004 18:40

Hi GRoberts

You are entirely correct, I read the post too fast and thought it was solid wire. I retract everything said about the voltage setting!

I believe that there has been good advice given about the problem in FCAW, so I will not hazard any more advice at this stage!

Regards
Niekie Jooste

By GRoberts (***)

Date 01-20-2004 02:13

Something I've done a thousand times myself. You can blame it on having to read upside down as the original post was probably typed in the northern hemisphere.

By cawelder (**)

Date 01-18-2004 02:36

I had this problem once. We tried everything, and ended up switching to CO2 gas. I dont know much about the wire you are using, this may not work. We were using 0.045 71M. Also, before switching the gas, check your Procedures. You may have to requalify.

Just a shot in the dark
Chuck

By brande

Date 01-18-2004 08:02

I had a problem similar to this a few years ago.

Running a 91T1 wire on railroad components.

Shop normally ran hard wire with 75/25, so we ran the FC wire on 75/25.
Worm holes, porosity and all that good stuff!!

Keep in mind, that if you were not getting worms and porosity with your last wire, be it hard or flux core, you should not be looking at flowmeters, hose, nozzles, and the like. It is often easy to overanalyse a problem.

Simply-if your process ran good before you changed wire-a good place to look is the new wire!!

My problem was happening on a Lincoln product, so I was very surprised. I've had reasonably good luck with their stuff. Should have done a little more followup, I guess.

Immediately upon changing to CO2, the porosity and worm tracks went away.

As a rule, the higher tensile flux cores seem to run better with CO2. Perhaps many are designed that way.

Is this true with every mfg.'s wire-I doubt it. I'm sure there are exceptions.

Keep in mind, too, in T-1 wires, that there are CO2 only wires and Argon Mix only wires. Running Argon Mix on a CO2 wire can give operational problems as well as an overhardening of the weld. So I am told. So I have seen.

Yes, there are wires formulated for both gasses, like many of the T1 stainlesses, for example.

For the most part-carbon T1 wires are either CO2 or Argon Mix. One or the other.

In the future-if you get the occasion to change wires or go to a new wire-get the spec sheet from the mfg. They are easily available from the internet these days and can really save some aggravation!!

Good Luck

brande

By ssbn727 (*****)

Date 01-18-2004 11:17

Hello again New Guy and everyone else!
So far, you've got some good responses!!!

Ed Craig gave me 2 responses based on your query verbatim...
1st) "The subject is covered in the pipe and flux cored section of this site and in my MIG/Flux Cored book.
The bottom line it's likely moisture has got into the flux. This is a common problem especially with Lincoln flux cored wires. By the way who is the wire manufacturer? The moisture can get into the flux due to poor wire manufacturing (poor wire joint seal), poor wire storage, (humid or damp location), no protection for the wire when it's on the (feeder) welder. Take note of the wire's storage and baking recommendations. Baking the wire before use sometimes helps, using a slightly longer wire stickout preheats the wire, use the highest possible weld current, slowing down weld travel and increasing the weld size all may help. Do'nt use all position wires for horizontal flat fillets, fast freeze slag." My question to new guy would then be to ask how old is this wire and what steps do you take to ensure that the wire is protected from moisture pick up?
2nd) "By the way type in the words "worm track" in the search part of this QA (the same goes for in the AWS forum but go back on the search at least 500 days) and more data is available.
Worm tracks are moisture or hydrocarbons. Think of them as an extended line of porosity (an elongated gas pocket) rising up through the weld trying to get into the slag but the fast freeze all position slag solidifies trapping the worm tracks (gas pores) in the weld.
Many companies use all position wires for welds in the flat/horizontal positions. They should use the EX0T-X wires which have a basic slower cooling thicker slag. Also these wires have more deoxidizers."
(brande, I agree with you about the moisture and switching to CO2 especially if new guy's using Lincoln man! I hope you'll show up for the Miller "squarewave" SAW Demo meeting coming up on February 7th @ the Steamfitter's local 449 union hall. It should be fun to hear and see how all the Lincoln rep's will react!!! Hope to see you and anyone else there!)
I noticed that in the pipe and flux cored data section in Ed's site recommends an E90T5-B3 wire for the A335-P22 pipe but I could'nt locate the A234-WP22 pipe because there was'nt any info on it...
Also, as mentioned by GRoberts and way back in 2002 by DGXL to watch out for your travel angle as you're welding. (I believe no more than 10-15 degrees under 90) I know this can be difficult between the pipes if there is'nt sufficient space to work from but, I do'nt think it's impossible to adjust for in new guy's situation.
Finally, as mentioned by Rod of God - wire stickout is also crucial.
(3/8 -1/2" stickout) With the wire to work distance, the tip of the wire should be as close as possible to the weld pool without making contact with the pool itself, adjust volts to set this arc length. If the wire touches - the weld spatter will occur, (sometimes even slag trapped underneath the root face that keeps showing up as worm tracks or wormholes in subsequent passes) provide a slight increase in volts.
(1/2 - 1 volt increase) If the arc length is too long the weld surface will be too fluid so an adjustment of 1/2 - 1 volt decrease will correct this condition.
If you're using Lincoln wire switch to CO2 (current/voltage settings may need adjustment if you switch to CO2) like brande mentioned but, if you do'nt want to switch to CO2, you could also throw "economy" out the window and use Alloy Rod's Dual-shield "Ultra" (My favorite! I do'nt know-who owns them now?) wire equivalent with the 75/25 mix if you do'nt mind spending the extra pennies per pound of wire for the job and based on the metallurgical differences in the 2 different pipe grades, your results should be more favorable if you switch to this higher quality wire but keep in mind to choose the right wire based on the position(s) you're welding from (Flat/Horizontal or All position)... Oh yeah btw, using the contact tips designed for FCAW will reduce the amount of tips you go through also, just a thought... I'd get a cylinder of CO2 if you want a quick fix if you're using Lincoln and make sure your wire (whatever brand) is protected from moisture...
Anywho, I hope that that all of us here provided you some direction as to how to go about eliminating your problem. Please let us know how you make out New guy!!!

Respectfully,
SSBN727 Run Silent... Run Deep!!!

By brande

Date 01-19-2004 04:46

SSBN-good to hear from you again!!

Anyway-I think everyone is reading more into New Guy's problem than what is there.

If the equipment and process ran well on other T1 wires-equipment and technique should not be the problem.

The only variable that exists is the wire. If we look there, we may find bad quality wire, wrong gas used, bad storage methods and the like.

My gut says the problem is in here somewhere.

Over my years in the business, I find most problems are cured by general corrections and not hi-end technical responses (ie. 1/2 volt here or there, triple point of gases, 1/4" of stickout, etc.). Most of the FC wires produced today are darn forgiving in operation.

I do value Ed Craig's advice. It has helped immensely over the years.

As far as the E70 vs the E71 argument, I am in total agreement. The E70 wires are very under-utilized as most FC welding is done in the flat position.

This can be a very difficult agument on the shop floor, I have found! Goes to"I've run Superdogweld E71T-1 on everthing-ain't going to change". Can you prove a difference? Yes it is difficult, not impossible, but mostly due more to politics than performance.

They also may see some operational differences going from an acid slag to a more basic slag type wires. There are some slight operational differences. Not as much as the true basic slag wires, like the T-5's. There will be a change in operational parameters, though.

Love those T-5's for problem welds, though! They don't care what they weld on. If there was a wire that would weld on wood, I'm sure it would be a T-5.

SSBN-yes, I want to attend the SAW squarewave seminar. This will be Miller's time in the spotlight. Like you, I will be interested in Lincoln's reponse. As you are aware, there is a lot of Lincoln representation in our chapter. Miller has always had the better, more innovative power sources, but remember that SAW has always been the place that Lincoln hung their hat!! They are very good at SAW.

Anyway, yell out my name a time or two, and I'll do the same-I'm sure we'll hook up there!

Good Luck

brande

By DGXL

Date 01-19-2004 19:14

new guy:
I have been monitoring this post with interest the last few days. Before I ask the one question I have since your initial post, just wanted to share.

Back in the mid 1990's, DOT/Caltrans inspectors were rejecting welds performed with E71T-8 (NR-232) electrodes that had the worm tracks on bridge column casings. It was later ascertained that the worm tracks (or chicken tracks) were NOT detrimental to the welds' integrity. As noted previously, it was due to the welder(s) technique including work and travel angles, arc voltage, WFS (amperage), weaving or stringers. Albeit these are self-shielding electrodes, some welds exhibited chicken tracks (lot's!), some welds had none. Obviously, the same welds with the chicken tracks were consistently produced by the same welders, while others never had these in their welds. The welders that produced the tracks tried everything they could to eliminate them, but to no avail. Unfortunately for these guys, the cover pass exhibited the best examples of what chicken tracks look like.

One important factor, weaving was the biggest and most obvious source of these.

My question to you now is:
Are the welds produced using the E91T1-B2 FCAW-G electrodes failing mechanical or NDT?

By new guy Date 01-20-2004 02:07

Thanks to all of those that took the time to reply but we went in today after having the weekend off and fired right up and have not had a problem (knock on wood) hopefully this will continue but if it doesn't we at least know where we can start looking for the problem. Thanks