Welding SMAW without interrun cleaning 5

Sayee:
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.

Aside from the problems of wind blowing away the gas in exposed locations, I always assumed that maintaining high quality welds without having to remove slag between passes was one of the reasons the GMAW process is becoming more widely used.

Blacksmith

Sorry,
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!

Sayee:
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.

Sayee:
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.

Thanks, CWIC, that was a lot of good information, especially since I had missed out on clause 5.30.1.

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!

A procedure has been qualified (NDT, bends and tensiles) in addition to the impact testing. NDT included Radiography as well as UT. But have not used this technique in my current job "on production" yet. Am still looking for the adv-disadv and whether this technique really merits a change of our technique of welding piles.

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!

sayee, as has been mentioned by others the "shortcut" of laying one bead on top of the edge of the slag line of a previous pass in horizontal welding is not recognized as the correct method. Like I said, shortcut. I have done it many times under the right circumstances with total success. The key of course is "right circumstances". All of my offshore welding experience could fill 1/2 the first line but, it was 100% UT and I did NOT fail to clean each pass. In a 'textbook' pass with E-7016 or E-7018 the slag pops off by itself. Sometimes but definately not always. Multiple pass welding without cleaning the slag with jet will leave you with enough pinholes---well, one best be very adept at carbon arc. All this is moot around the Los Angeles area as NO AWS inspector will buy this type of welding if he catches you doing it, regardless of test procedures. Like I said, it's a shortcut and we know the problems we get into taking shortcuts.

Rod

Granted with all that was said about this being a shortcut, but the salg cleaning is going to be carried out after each layer and not between runs in a given layer. The thing is that the fluidity of the slag and the gravity and whatever other forces act on the weld and slag when fluid, cause the slag to be very thin to non existent at the top of each run when welded in 2G position and it is this which I feel can be utilized to benefit by the tchnique mentioned above. And thanks to all the guys who posted replies here, when we have a procedure in place(If at all) I will post the results here for the use of others. The post is still open to comments and feedback if any!

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!

I have "Slag Welded" many boiler tubes of Carbon Steel, 1-1/4 Chrome and 2-1/4" Chrome with acceptable RT results. The method works only on Horizontal welds. The slag from a 7018 will be VERY thin on the top half of the bead. The next bead stacked on top has no problem melting out the underlying slag provided te beads were properly placed.

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 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

Gerald
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!

Pipewelder1999, The welding procedure is designed to eliminate the possablilty of defects as best it can. I can tell you from experience that when welding up UT reference plates while trying to deliberatly installing discontinuities that may or may not meet specifications I had a hard time until I switched from 7018 to 6011. But, I still came across plenty of weld joints made out of position (not flat for all you non-welders) that had slag inclusions made with 70XX, 80XX and even 90XX.

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 ...

As I said in reply to this question on another forum, this is a common practice on pile splices. It generally is not a problem due to the often mentioned lack of slag covering at the top of a horizontal bead. It doesn't, in my opinion, increase the speed of making the weld by much. It is usually done as a matter of convience. The welder is probably working from planks, over water, wearing a flotation vest, going around the pile in circles. making the weld in an akwardly low position because the non-welding pile driving foreman has once again driven the piles too low for the welder to enjoy even a small amount of comfort, and dragging that grinder w/ wire wheel or needle scaler with him as he goes and not knocking it into the drink is just that much more trouble. So, our welder puts an entire row of weld on the pipe, then cleans it. Inspectors may frown upon or even make them stop the practice. I have had jobs where one of my welders made pile splices while leaning over the side of a small boat because the pile was driven within 10" of the water. The boat was too high for him to do a good job and we ended up floating a crane mat out as the top of the mat was only about 6" above the surface of the water.While laying on the mat he made a very slick, code quality weld on 36" .5oo wall , grumbling all the time, no one had the nerve to suggest interpass cleaning to my very irate welder.

regards,
JTMcC.

Rjeffery,
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.

JTMcC,

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?

I may have missunderstood your reply, but if you are casting doubt on the truth of my tale I will gladly give you the name's and phone numbers of those involved. The welder is a good friend of mine and does'nt mind telling the sad tale, the P/D foreman is currently in No California for Kiewit, he was trying to hold the crane float somewhat steady and would probably enjoy verifying the story also, after the welder told him he wasn't going to make the weld, the P/D foreman offered a case of beer and double time for the day and assorted other incentives.

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.

The Skill of the welder is the thing you have to count on regardless of what the WPS says. There is no WPS required variable for bead placement, contour, arc length, method of manipulation, what to do with arc blow, grinding method, how to bend the rod, place the mirror, deal with variations in fitup, weld in positions in which there are valve handles in your ribs etc.

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

In the gas distribution work I have done, the welder was required to have a copy of the procedure he was using at the time in the truck, and, he has to be familiar with it and answer any questions about it that the state inspector asked. Failure to produce a copy and answer the questions result in the job being shut down.

JTMcC.

In our non distribution Pipeline work, the welders are informed and expected to be aware of and follow the procedure to the letter, with almost one inspector for each welder. In our Piledriving and structural work it varies from strict understanding and compliance to the procedure, to a more relaxed situation where only rod, preheat, and vague joint geometry is specified to the welder. And, sometimes, they don't want to be bothered and leave it all up to you.

regards,
JTMcC.