Welding SMAW without interrun cleaning
Welding SMAW without interrun cleaning
(OP)
When welding the piles offshore one of the main criteria is the welding productivity. To decrease the time of welding(Horizontal position with 15 Deg bevel on lower tubular and 30 Degree Bevel on the upper tubular), upto 6.3mm electrodes are used effectively. Now, I have seen welders doing it in other positions and would like to know the nuances and precautions as well as the adv/disadv of using what some people call "slag welding". What it means is that for each layer, no cleaning of the slag is done in between runs . But by the welders' skill the slag is broken down and the turbulence of the weld metal and the arc force bring the slag back to the top(The slag cannot be remelted by the welding arc). Then after the completeion of each layer, the slag is wire brushed. What this would mean is that the cleaning time after every run can be avoided and cleaning time thus minimized. Anyone having any feedback/experience/comments please?
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!





RE: Welding SMAW without interrun cleaning
You did not mention what type of electrodes used for this practice. Certain types of electrodes will lend themselves to this type of workmanship (or lack thereof). This would include cellulosic electrodes. This would not apply to electrodes with a slag system designed to maintain a specific arc length.
All of the welding codes I have used in the last 29 years prohibit this type of welding for obvious reasons.
What about the governing document(s) that the work is performed to?
Does the code, standard or specification prohibit this type of practice?
Has anyone examined the welds you mention by NDT or other means to ensure slag entrapment is not present?
I have seen welders over the years attempt this without success although a few have been able to pass NDT, but not mechanical testing (bend and tensile). Curious about other mechanical properties of this weld metal such as toughness/impact.
Whenever the talk of cutting corners reagrding welding workmanship or technique is about, I have to wonder how a particular practice or procedure has been verified. The photos that I archive when a welder welds over a slag covering may possibly change the welders mind.
In addition to the risk of inclusions in the weld metal, also note the SMAW electrode may have a coating which when consumed during the original weld (before slag welding) may have lost it's chemical, alloying, shielding, etc. properties. Most designers I now would never permit this type of welding.
Please let this forum know how these welds have been tested to ensure the acceptance criteria has been satisfied.
RE: Welding SMAW without interrun cleaning
Blacksmith
RE: Welding SMAW without interrun cleaning
Consumables: E7016-1(DCSP) for root, E7018-1(DCRP) for fill and cap
The code: AWS D1.1, no reference prohibiting this type of welding practice, though no reference of acceptiong the practice too.
I have had welders weld this way and still impact properties meet @-40 Degrees C.Any more suggestions/comments welcome.
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
RE: Welding SMAW without interrun cleaning
The D1.1 code has always required cleaning between each pass. This is noted in section 5.30.1 of the 96 - 02 revisions of the code. The code denotes "Before welding over previously deposited metal, all slag shall be removed and the weld and adjacent base metal shall be brushed clean. The requirement shall not only apply to successive layers but also also to successive beads..."
But, as you noted you are still meeting your impact requirements. I would assume a procedure has been qualified (NDT, bends and tensiles) in addition to the imact testing?
Interesting. I'm still curious if the production welds are being tested 100% by some type of NDT (RT/UT) to verify conformance to the code.
RE: Welding SMAW without interrun cleaning
Something I have not mentioned previously. I have tried this practice back in my day as a production stick welder. It actually slowed me down as it takes time to manipulate the electrode to remove the previously deposted slag. There was also a waste of electrode trying to remove the previous layer of slag in the form of excessive spatter loss.
I would think this practice would not be as productive if the slag was removed in the normal manner. The brand of electrode may make a difference, many electrodes of the same classification/specification perform differently.
RE: Welding SMAW without interrun cleaning
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
RE: Welding SMAW without interrun cleaning
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
RE: Welding SMAW without interrun cleaning
Rod
RE: Welding SMAW without interrun cleaning
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
RE: Welding SMAW without interrun cleaning
I have also performed this on weld metal buildup of eroded pressure vessel walls made of carbon steel.
Many an AI have witnessed this practice with NO problems.
There is ABSOLUTELY no increase in porosity in the 1000 or more boiler tube waterwall welds I have made using this method for capping the welds. If the joint configuration would require me to weld over the heavy slag that is hanging off of the lower edge of the bead, I chip it.
I know what all of the codes and WPS's say. Unfortunately sometimes the people that prepare those documents don't get in touch with the skilled labor doing the work. Some of this stuff is NOT rocket science.
How many welders in industry actually get to see a WPS.
It's some secret document often times kept in a book allowed to be viewed only by document control people, engineers and inspectors. Justification of existance maybe ?
As with any practice, it is very dependent upon the situation. ASME does not restrict this practice based on my reading but I may have missed something over the years. (Man thats a large number of NCR's to be written)
Regardless of whether slag is ALL removed or not or not, the bead placement and contuor of the bead is the greater factor on whether or not inclusions/defects occur. The sketches at http://www.weldinginspectionsvcs.com/WeldCapProfile.htm show two examples of bead placement. The second method shown would be much more likely to have defects in it if a second layer were welded on top of it even if ALL Slag was removed.
Sometimes a shortcut may be the road most traveled by some if they have the ability to use the map and the ability to control the vehicle.
Have a good day
Gerald Austin
Gerald Austin
Iuka, Mississippi
http://www.weldinginspectionsvcs.com
RE: Welding SMAW without interrun cleaning
You deserve at least two stars for that reply. and I have already visited your site a couple of times but missed out on the bead placements(I in fact used the weld volume and costs calaculation(especially the excel sheet you have quite extensively). Once again thank you for your reply.,
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
RE: Welding SMAW without interrun cleaning
The skill of an individual welder Is one thing that cannot be counted on when developing a WPS. In that respect it is not rocket science, but we must remember that quality not pride is at stake here. Joe Journeyman Welder may not have the experience (as you do) to recognize when to clean and when it is safe not to.
I recomend, at a minimum that each pass be mechanically wire brushed or ...
RE: Welding SMAW without interrun cleaning
regards,
JTMcC.
RE: Welding SMAW without interrun cleaning
I believe the welder's skill level in this type of work isn't a wild card. We know what minimum level he is capable of due to the welding test required, and ongoing inspection, UT, X-ray ect. Granted there is a wide variety of excellence above that requirement, but don't you think it's safe to assume he has attained or exceeded that minimum level?
regards,
JTMcC.
RE: Welding SMAW without interrun cleaning
With all due respect, I passed my first SMAW qualification test assembly in the 6G position in the shop and have welded in most any odd position (except, possably hanging from my heals) The story related here by you is one that I don't think that I could have duplicated even though I have 20 years in the US Navy (retired now though) Still, most of the welders I know are excellent. Most will not admit that they breath a little easier after the NDT guy (gender neutral term) passes the moment weld that they have spent the better part of the day 20 stories in the air welding.
The question is, If they can weld moment connections sitting on the beam (flat position) and still have them fail, albet only 1:250 or so, then why would any welder worth their salt not want to take all the measures they could take to make the product they are being paid to produce the best possable?
I have seen corners cut that resulted in death, destruction and law suits. Interpass cleaning is a requirement not a suggested practice. I weld and I have my CWI card and I read and interperate radiographs, run a KKB 48 and can Mt and PT with the best of 'um. I feel like crap if my weld fails so I do every thing I can to prevent it. wouldn't you?
RE: Welding SMAW without interrun cleaning
I never questioned your credentials. I work with and around welders every day so no offense but your about the 375th guy to tell me how slick you are this year. I'm sure you are however.
I never condoned or recomended the practice. I simply observed that it is commonly done.
You didn't answer my question about your comment that "the skill of the welder cannot be counted on", I think that is part of the reason for testing and inspection, so the skill of the welder CAN be counted on.
regards,
JTMcC.
RE: Welding SMAW without interrun cleaning
I have seen very few rejected welds because the WPS was incorrect. That pride that welders have carries MUCH more influence on the quality and fitness for service of a weldment than does the WPS in most cases. I agree that there are cases when a WPS is a valuable tool but I am also pretty confident in welds made by a skilled craftsman without a WPS than I am in the welds made my a less skilled craftsmman with a WPS bascked up by a ton of PQRs'.
Anyone can follow the variables contained within a WPS with very limited skill. Those things that are NOT contained within the WPS will make the difference.
In my limited experience welders are not given a WPS to follow unless some type of audit was going to be going on. In some industries this is not the case but I think that there are more WPS's gathering dust in a book that there are in the field or shop.
The WPS does not have any content in it that I have ever seen that reduces the chance of defects as much as the skill of the welder.
I think the WPS should be available to all welders making welds in which a WPS was submitted for. ASME and AWS indicate the WPS is the procedure for welding, yet the welder seldom has this at his or her disposal.
I spent about 6 years in the Navy myself and we did use a WPS. During one period of time we were put on report if we had three rejected welds in a month. You can be sure that if we had those three bad welds, the CO was not calling the organization that prepared the WPS to make sure it was properly prepared.
As with most subjects, there are many variables that make each situation unique. This is a great place to share those experiences and continue to learn.
Thanks for your feedback
Gerald Austin
Iuka, Mississippi
http://www.weldinginspectionsvcs.com
RE: Welding SMAW without interrun cleaning
JTMcC.
RE: Welding SMAW without interrun cleaning
regards,
JTMcC.
RE: Welding SMAW without interrun cleaning
The point here is like JTMcC said, the welding of offshore related work like say for piles is entirely dependent on welders skills and less on the WPS developed for the process. The PQR might have been qualified in an ideal condition in the workshop but hardly replicating the conditions the welders are working in while offshore. The key there is to have the joint welded between two pile sections as quickly as possible and ready for hammering in. The point to be noted is as a welding engg with a little less than 10 years experience in welding in various industries including aerospace and with materials from Ti to Al to CIs has hardly prepared me to argue with the welder in this particular case. The welders for offshore understandably might be paid more than me only because so much hinging on their experience to get the welding right as there is hardly any time for repair of welds. I have seen welders successfully using this technique and would hardly question their criteria when welding a 50"+ dia and a 2"+ WT because I want to speed up welding too. I cannot use a higher deposition rate process like FCAW because of the welding conditions and that is why the welders even end up using 8.00 mm electrodes in this type of welding. I have run procedures replicating this technique which has been successfully tested for mechanical properties & even impacts. What I wanted to discuss in this forum is the +es and -es of such a technique which I can use as an arguement to clients in case they have some objection which I got from all your replies.
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
RE: Welding SMAW without interrun cleaning
I am the author of the spreadsheet that you downloaded from Gerald’s web site. Since you seem to like the sheet and use it extensively, I would like to give you the full version. This full version is quite a bit more extensive than the one you have and is about 4 MB long. Let me know where I can e-mail it to you. Thanks for the feedback.
Mark
RE: Welding SMAW without interrun cleaning
I am not casting doubt towards the truth of your tale nor towards the skill and perseverance of your welding friend. I have seen welders working in many awkward positions, and having the weld pass after working in the position you describe is more than remarkable it is admirable!
I, on the other hand, am not as slick as your friend is. I could not have accomplished what HE did. (Please de-increment your slick welder count by 1) No way, not on my best day. I am Joe Journeyman, the average (and I may be over evaluating that!) welder that the procedure is written for.
If every welder had the same level of skill, knowledge and experience as your welding friend then the skill of the welder would not be a wildcard in the quality equation. If he and I were side by side in the same bobbing boat trying to weld the pile splices, even in a calm sea state, he would weld rings (pun intended) around me.
The WPS was developed in the shop where the floor does not move, the walls do not sway and the wind does not blow your shielding gas away. It was designed to give a welder, at any skill level, the essential variables to perform the welding with a reasonable expectation of producing a sound weld. Reasonable expectation I think is the key. Those ‘welders’ that do not have the skill set (yet) will fail. But with experience… But again, that is in the shop and not onboard ship, 15 stories in the air or leaning over the gunnels of a boat trying to weld piles.
When I proctor welding exams, I want every welder to pass. I do all I can to ensure that happens. I would never suggest that the slag not be cleaned out of the toes of the weld or that the next pass will burn out the slag. I would never annotate the welder’s record indicating that he (or she) could, in fact, produce a sound weld coupon without interpass cleaning of the stringers.
Yes it is a pain in the a$$ to have to clean the stringers between passes. If cleaning them will help guarantee the weld will pass then I’ll clean them. If the time it takes to weld, then clean maybe then a welding helper/laborer should be employed to clean them while the welder welds? “Pay me now or pay me later,” said the Piper. Short cuts may save time, now and then but they can kill more than reputations. To get quality one must be prepared to pay for quality.
As you have correctly pointed out it seems to be common practice not to clean the stringers between passes. Just because it is commonly done doesn’t mean it is proper or correct and I feel any one who does not clean their welds are taking an unnecessary chance.
Again, I did not mean to intimate that you were being untruthful in any way. Nor did I intend to besmirch the talent and skill of the welder you related the story about. I only intended to make the point that over looking or encouraging a welder to eschew cleaning of his stringers between passes is asking for inclusions and should be avoided.
RE: Welding SMAW without interrun cleaning
Fair enough!
It was a calm day on a small lake, Lake Las Vegas, if you ever go to the casino built on the bridge over the lake, on the north side, that's where my man made his world famous splice! : )
We'll just have to differ on the one point.
regards,
JTMcC.
RE: Welding SMAW without interrun cleaning
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
RE: Welding SMAW without interrun cleaning
"I am the author of the spreadsheet that you downloaded from Gerald’s web site. Since you seem to like the sheet and use it extensively, I would like to give you the full version. This full version is quite a bit more extensive than the one you have and is about 4 MB long. Let me know where I can e-mail it to you."
If this is just a part of the actual spreadsheet, I'd love to have the whole spreadsheet. My email id is spraghunathan@mcdermott.com
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!