Testing of Low hydrogen welds w/ wet rod

Date 04-06-2004 23:34

I think you're talking about measuring the diffusible hydrogen content of the deposited weld metal. This will have to be done on a test weld or cut a boat sample from the field weld. I believe the test is described in either AWS D1.1 for qualifying extended atmospheric exposure times, or is described in AWS A5.5. There may also be another AWS standard on this. Try searching the Publications link on this website (http://www.aws.org/).

By MBSims

Date 04-06-2004 23:42

I found the title for the AWS standard:

A4.3-93 Standard Methods for Determination of the Diffusible Hydrogen Content of Martensitic, Bainitic, and Ferritic Steel Weld Metal Produced by Arc Welding

Follow the links on the AWS Publications web page to purchase a hard copy or electronic copy.

By rutgersgrp Date 04-07-2004 00:02

Thank you for your response. Will determining the content of hydrogen indicate if the weld is acceptable ,i.e strength, durability, and future corrosion? thank you again

By MBSims

Date 04-07-2004 01:21

I don't have D1.1 here at home, but I believe it has specified limits for diffusible hydrogen content. If the weld meets those limits, then there would not be much concern for hydrogen cracking /underbead cracking. The sensitivity of a particular base metal to hydrogen cracking is somewhat proportional to the tensile strength and carbon equivalent. With most steels welded with E70xx rods, hydrogen cracking is not as much a problem as something like A514 quenched & tempered material, but it can occur depending on degree of restraint and section thickness. I have also seen a lot of A36 welded with improperly stored low hydrogen electrodes and cellulose-type electrodes that has performed fine for the service conditions it is used in. For welding structures subjected to dynamic loading, hydrogen content would be more of a concern than a structure subjected to static loads. So there are several factors that must be evaluated before one can determine if a particular diffusible hydrogen level is "acceptable", such as carbon equivalent, tensile strength, loading conditions, and applicable code requirements. There is a good book on the subject titled "Welding Steels Without Hydrogen Cracking" by Norman Bailey, et al, if you are interested in the subject. It can be purchased from ASM International at their website.

Also, I should mention that measuring diffusible hydrogen content of weld metal must be performed by a laboratory. You asked about methods a CWI could use and although the CWI could select a test sample representative of the field welds or supervise welding of a sample, the actual measurements require the sample to be sent to a lab. As a CWI, you can only determine if the electrode storage practices meet the applicable code, standard or engineering specification and identify nonconformances to the organization you represent for evaluation by an engineer competent in the subject matter.

By jwright650 (*****)

Date 04-07-2004 09:40

Thanks Marty for explaining the "what if", when we find welds welded with improperly stored rods. I had often wondered "what if", and if I had ran across it, what is one to do about it, after the fact. I've given warnings about improperly stored rods, but haven't ran across any that was already deposited, at least that I knew about. :)
John Wright

By CHGuilford (****)

Date 04-07-2004 17:04

I just want to add that if you know for sure the electrodes were not stored properly, then the welds are automatically rejectable. At that point, it is up to the contractor to prove to the engineer that the welds are acceptable.
Chet Guilford

By rutgersgrp Date 04-08-2004 00:01

Thank you for your response. We do know that the rods were stored improperly. We saw the rods were discolored. We are looking for a way to test the welds to determine if they are "acceptable." Thanks

By ssbn727 (*****)

Date 04-08-2004 05:27

Hi rutgersgrp!
As Chet mentioned, it's up to the contractor to prove to the engineer to determine whether or not the welds are acceptable...
Since you asked what a CWI would do? Chet is also correct in saying that it's an automatic rejection if it's known that the rods were improperly stored, no test is needed to be performed by the CWI!

The only way to validate this would be to have an independant lab that the engineer is satisfied with to perform the appropriate examination in order to avoid the possibility that the engineer may raise a question regarding a conflict of interest if the examination were to be performed by the contractor or one of their employees...

Of course, this will add costs to a situation that may be better allocated to remove and repair the welds in question so, it's kind of like a "roll of the dice" in taking the chance of someone else independantly accepting the welds as compared to just performing the repair...
I would suggest to repair the welds in question especially if the contract specs include a provision for proper storage of the low hydrogen electrodes...

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

By rutgersgrp Date 04-08-2004 09:40

Thank you for suggestion. However, the question is what type of recognized and accepted testing should the independent testing agency perform. Visual/mag/dye will only provide visual clues about the surface weld quality. Nothing about the heat of fusion, present/future corrosion, or strength of the welds could be determined. Keep in mind some of welds maybe satisfactory. Performing a metalurgically analysis on hundreds of welds is impractical and cost prohibitive. Thank you again

By jwright650 (*****)

Date 04-08-2004 10:05

It may be like qualifying a procedure, have the contractor that placed the welds use some of those "unconditioned rods" to weld up a mock-up and have the mock-up tested. I'm purely guessing, so take that for what it's worth, but it may save cutting apart all those joints to prove the serviceability(sp?) of the welds in question.
John Wright

By thcqci

Date 04-08-2004 12:20

I agree with Chet. Well stated.

John's suggestion in his last post could be valid if the Engineer accepts the test as essentially equal to weld metal already deposited in like conditions. If I were the contractor at this point in time, I would throw that up against the Engineer's wall to see if it would stick. The alternative could get quite costly. Amazing how important those little rod ovens can become in the field. Yet in visits to the field now, I have had to suggest repeatedly that erectors get his out of the tool bin or trailer and actually use it before they get burned by the field inspectors. Supposed to be an AISC certified erector also!?

By jon20013 (*****)

Date 04-08-2004 12:24

I may well end up sounding like a B*stard here..... but, were it me doing the inspection I would reject ALL of the welds which were placed using wet low-hydrogen electrodes. This based on the "Rebake" criteria stipluated not only in D1.1 but also in the filler material specs. And, might add; shame on the inspector for permitting this to happen IF that is what happened! Even with testing, the inspector will still not be able to determine (in my own opinion) the long-term consequences of potential hydrogen embrittlement and may even be putting themselves out on the chopping block for possible legal actions. Again, these are simply my own opinions.

By jwright650 (*****)

Date 04-08-2004 12:45

We all should know about the use of the words used in code like "shall not", "shall" and "should", so this most certainly falls under the "shall not" category. D1.1:2004 para. 5.3.2.1 last sentence in the para. states..." Electrodes that have been wet "shall not" be used."
But now it's a "What do you do now?" question that has to be answered. It is clearly written in the code and the Commentary on this lists the reasons why these restrictions are placed upon low-hy electrodes. I'm afraid this could get very ugly for the contractor that placed these welds.
John Wright

By Lawrence (*****)

Date 04-08-2004 12:49

Jon, I diddn't want you to feel alone out there so....

Why is Lo-Hy electrode storage so important, and more strict than ever?

One answer would be the evidence obtained from structures destroyed by the earthquakes in Kobe Japan and Los Angeles. Those were in the most real sense "testing labs" that proved that the condition of electrodes *is* important. The codes are there for a reason and its just not always possible to easily undo mistakes like you have outlined for us........ and come to think of it, its pretty hard for me to swallow the thought that, neither Welders, leads, or supervisors diddn't know better than to apply wet electrodes to a code job. Thats not a mistake, its gross incompetence due to blatant disregard for codified procedure.

Its just not the job of a CWI to perform tests on the mechanicals of welds found to be rejectable due to wet electrodes. While its still possible for some engineer or mettelurgist who examines those mechanicals to be a CWI, the task itself is way beond going the extra mile for an onsite inspector, at least as I understand the duties.

There is no cheap (inexpensive) way to validate what has happened. It can be pencil whipped or a large expenditure can be made. Where can their possibly be a middle ground?

By jon20013 (*****)

Date 04-08-2004 12:33

rutgersgrp: Again, my own opinion here but I think you are setting yourself up for something you dont want to get into. I also always look for "loopholes" or ways to work within the standards with my contractor/employer BUT there are some instances (this being one) where the contractor clearly did wrong and sounds like even KNOWINGLY did wrong. If I were the inspector I would simply reject all of the affected welds. If I were the engineer or a consultant to the contractor I would simply explain that the potential risk of litigation (and possibly loss of life in the event of catostrophic failure) largely outweighs the savings of NOT repairing welds which are, in fact, of indeterminate quality.

By CHGuilford (****)

Date 04-08-2004 13:52

rutgersgrp,
To expand on this a bit more. It seems you may be looking at this from a "possible and practical" point of view?

MBSimms has already mentioned a test that could be performed if need be. Of course that is destructive to the weld and would require re-welding, at least for where the sample was extracted from. The test would provide some information on what one might expect for other welds. Trouble is there are more variables to consider such as how long the electrodes were stored improperly, was the tested weld made with the same parameters as other welds, what steel grades and heats were used and where. And so forth. Usually you won't find any records to answer those questions.

Of course, the engineer can look at weld locations and determine weld criticality. Obviously, a base plate for a column that has only a down-force would be a reasonable risk, while moment connections could spell disaster.

While it would be nice to have a cheap, easy way to check a suspect weld, I don't believe there is any, at least not yet. Anything done now to test those welds is just an educated guess. The cheapest insurance would have been to have a rod oven and keep it plugged in. The contractor should know that, so he either failed to do his homework or decided to gamble.

But in the long run, the contractor should be responsible for proving the weld integrity. And that is also a gamble. If the results are not accepted by the engineer, the welds will still have to be replaced.
So possible? Probably. Practical? I think not.

Chet Guilford

By jon20013 (*****)

Date 04-08-2004 15:23

Possibly one thing missing in all of our responses is to determine who, or what level of responsibility rutgersgrp is. I havent seen anything that would tell me his is either A). The Inspector or B). The Engineer or C). A Consultant to one of the parties. I think he has received some valuable input but it would be much easier to address his specifics if we all knew from what discipline he is asking from.

By ssbn727 (*****)

Date 04-08-2004 19:18

Hi Jon20013!

I may be incorrect here but, I think this person either works for the contractor or is the contractor...

The way I figured it out is from the manner and choice of terminology in which this person is describing their situation... It's obvious to me that this person is trying to avoid the costs involved in repairing ALL of the deposited welds in question!!! It makes me wonder if they even have a code book for reference on how to go about rectifying this ugly as JW mentioned situation???

Maybe this person could shed some light as to the title this person has in this particular case as you mentioned... Of course, this is just my opinion also...

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

By CHGuilford (****)

Date 04-08-2004 20:58

You could be right SSBN. I had thought that too but figured it didn't change my opinion any. I certainly understand wanting to save money but we all have to be careful of "stepping over a dollar to pick up a dime".
Chet

By ssbn727 (*****)

Date 04-08-2004 21:15

Hi Chet!
As always, you hit the nail right on the head!!!
I could'nt have said it better myself!!!

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

By rutgersgrp Date 04-09-2004 18:40

Thank you for all of your reponses.

By vonash

Date 04-16-2004 00:51

[deleted]

By jon20013 (*****)

Date 04-16-2004 13:30

vonash; I'm sure many of us recognise the tests you're describing but, with all due respect, how does this prove, disprove or otherwise address the potential for hydrogen embrittlement cracking which are commonly delayed and may occur days, weeks, months or xxxx period of time after the welds have been made? While we know the electrodes used were of low-hydrogen variety, I dont believe we were given any description of the base metals. Am I missing something here?

By MBSims

Date 04-16-2004 14:29

Back in the early 1980's, the folks I work for tested several brands of E7018 electrodes to qualify extended atmospheric exposure times per AWS D1.1. We had about 4 or 5 different manufacturer's electrodes that we placed in a chamber with a humidifier to create 100% humidity (just short of rain). The electrodes stayed in the chamber for 15 hours, then to a 250 F rod oven, then back to the chamber. This was performed for about 6 iterations, then the rods were taken directly from the chamber and a 1" thick x 18" long test plate was welded by each. The test plates were radiographed per D1.1, then after a couple of days tensile and bend specimens were cut and tested. Samples of the electrode flux were taken right after coming out of the chamber and placed in glass bottles sealed with parafin, the sent to a lab to determine moisture content. The end result was that one brand had the flux falling off after the last trip to the chamber and could not be welded, but the remaining brands all passed the tests with varying degrees of porosity in the radiographs, but still meeting the mechanical tests. This was all done on A572 Gr. 50 plate.

So, I was quite impressed with how much moisture can be tolerated in the welding of mild steel plates and still produce sound welds. This would not likely be true for some HSLA and air-hardening alloys (e.g. CrMo steels). I think a reasonable approach to resolving the issue would be to cut out one of the welds, subject it to radiography, tensile, and bend tests; and determine the diffusible hydrogen level per the AWS standard mentioned above. Then perform MT of all of the field welds made with the overexposed electrodes to verify no cracking exists. If cracking is found in the field welds, all welds should be gouged out and rewelded, or subjected to a postweld hydrogen bake-out for 4-6 hours at 500 deg. F or higher. If the welds fail mechanical testing, all welds should be gouged out and rewelded.

By jwright650 (*****)

Date 04-16-2004 20:14

Hi Marty,
You know the longer this situation sits and people do nothing, the costlier it will get, if the welds are to be gouged out. As other trades move onto the site and the building is being erected, walls are being laid and a lot of this steel with questionable joints are being covered up. I hope they get busy in determining the soundness of those welds or the owner is going to be left with a building and everyone responsible gone on to other jobs, probably to do the same thing over and over.
John Wright

By rtstrong Date 04-29-2004 14:42

I would also reject all of the welds, have them all cutout and re-weld the joints.

By brande

Date 05-08-2004 04:39

This is really not as hard as it seems.
I also could be over-simplifying as well. I've been accused of that before.

I have read most of the other posts, and the concern whether the CWI works for the contractor (QC) or the client/engineer (QA) really doesn't matter, from what I see.

One of the main duties of a CWI, regardless of which side of the fence he is on, is to verify proper filler metal and it's quality. It is one of the reasons a CWI exists.

If proper storage cannot be completely verified, it is an automatic fail from any CWI-period. Or should be, if he is doing his job.

All is not lost for the contractor, however. If presented with this situation, he has the option of contracting an approved independent testing lab to check welds for hydrogen and other bad stuff. The contractor, of course, is responsible for this cost. A situation like this would require testing of every weld, as well.

Contractors usually only go down this road once. They soon find a few boxes of new lo-hi and a rod oven are much cheaper than the alternative.

Another note-even if the contractor has the blessing of an independent lab-usually the engineer still has the right to accept or reject the testing labs findings. It is the engineer of record's project and he really does have final say. Most codes reinforce this.

BTW-if a rod changes color-there it a good chance it is junk. There are rebaking procedures, but most rod ovens will never get to the rebaking temps which are in the 600-750f degree range (check with manufacture's recommendations). There are baking ovens and holding ovens. They are not the same.
The rebaking is time sensitive as well. If there is no way to verify this time-this could cause problems.
Filler metal costs in most instances are but a very small part of a job's actual costs.
If you are working code-it's just not worth it!!

Good Luck
brande

By bmaas1

Date 05-08-2004 19:42

It looks like the way it stands right now all the welds are suspect. That means that EVERY weld must be tested or examined. If it can't be done without destroying the weld your better off just removing and rewelding at the start especially if there are any moment connections.

Just my thoughts,

Brian J. Maas

By billvanderhoof (****)

Date 05-09-2004 05:52

I have no idea what size sample a lab would require for analysis but it could be that the drill chips from a small hole through the weld would be enough. You might not even have to repair the hole.

I wonder why the manufacturers don't enclose smaller amounts of rods (say a pound) in plastic sleeves within the 50 lb box. Probably wouldn't cost much and you would almost always use a pound up before they timed out. You wouldn't even need the rod oven in most cases.

Bill

By Niekie3 (***)

Date 05-24-2004 18:00

Hi

I have read the other postings on this very hot topic. I will give my opinion, which may be at variance with most other people's. (It is also much later than when you posted the original post, so you have probably sorted something out by now.)

The primary reason for limiting H in the welding consumables, is to prevent hydrogen cracking. (Also called cold cracking; delayed cracking etc.) This cracking can typically take place from seconds following the welding, to about a week. (The most widely accepted maximum time to cracking is 72 hrs, although it can sometimes take longer.) H cracking occurs when:

1) The hydrogen content in the weld is high enough. (Too high)
2) You have a susceptible microstructure.
3) You have high stresses.

Some materials (e.g. thin section low C/Steel) can be welded with very high moisture content consumables before you will ever get a problem. This is so, because they never have a susceptible microstructure. By the same token, some steels, especially in thick sections will require very low H concentrations to prevent H cracking.

If you can proove that there are NO failures of the welds after a week, then essentially there should be no risk in putting the welds into service. The trick is PROOVING that there are NO defects that is difficult. We have to keep in mind here that these cracks can be very small in some instances. This means that you will typically have to perform the following tests on every weld:

1) Surface crack detection of all surfaces surrounding welds. (Typically MPI)
2) 100% UT testing of weld metal and adjacent parent metal.

In many joint configurations, 100% UT is essentially not possible / practical.

The lab test for measuring the diffusable hydrogen content is usually performed under very controlled laboratory conditions, and I do not believe that this test is applicable for your situation, because there are time limits between performing the welding to performing the testing. Even if you are able to get a meaningfull sample, I still do not believe this helps you, because it will not tell you if you have cracking or not. It will only tell you that your electrodes were contaminated, but this you already know!

In the final analysis, I think that you have to see if the conditions warrant the required testing, and if this will be cheaper than just replacing the welds. Also, somebody needs to take responsibility for this. (over rulling code requirements) This person will only feel comfortable doing this if they are comefortable with the underlying metallurgy involved. This means that most typical mechanical engineers will not be happy with doing this.

Hope this helps.

Regards
Niekie Jooste
Fabristruct Solutions

By jon20013 (*****)

Date 05-24-2004 20:00

Very well said Niekie and I agree.

By jwright650 (*****)

Date 05-24-2004 20:35

Hi jon,
I think all this just goes to show why the low-hy rules are written into the various codes and should be followed, to avoid all of this testing or guessing to prove if the welds are OK or not. Use good rod storage procedures and follow them and the resulting welds will be trusted to a greater degree.
John Wright

By Niekie3 (***)

Date 05-25-2004 07:50

Hi John

Absolutely. As we can see, there is NO substitute for just doing it right the first time. Plan B is always just so far behind plan A.

Regards
Niekie Jooste

By Jim Hughes (***)

Date 06-15-2004 01:00

First of all take your CWI cert and throw it away. This is waht I have been talking about. A good inspector would have rejected those welds just with the info you mentions. This is inspection 101. If the production group is violating filler material control. ( look on the low/Hydogen package if you don't have a QA/QC program) you have to step up to the plate and require them to remove those production welds and reweld with the proper filler material that has been controled.

By ssbn727 (*****)

Date 06-17-2004 00:22

Hi Jim Hughes!

I've noticed some of your replies here in this forum and some of them share some good advice but, I think your attitude towards CWI's is unacceptable to most of the individuals that frequent this forum!!!
I just took the exam recently and it was NO JOKE!!!

In other words, IF YOU HAVE A PROBLEM WITH THE AWS REGARDING CWI's THEN, TALK TO THEM ABOUT YOUR ISSUES IN HIRING CWI's!!!

HOWEVER, Please do not insult people here that are only trying to help one another instead of encouraging certain individuals to throw away their CWI papers... THAT IS NOT THE PURPOSE OF THIS FORUM!!!

THERE ARE QC's (code of conduct) regarding how you should behave in this forum that you may have to review or have somehow overlooked... Being that you're so well versed in reading codes in the first place - it may be a good idea to check that code out!!!

NOBODY's PERFECT, and here's a newsflash: THE SAME APPLIES TO YOU and MYSELF!!!
So let me finish by saying; WELCOME TO THE FORUM!!!

BTW, if you could tone it down a tad, I believe you'll find more acceptance as opposed to confrontational responses from the rest of the great folks here in this AWS forum. Believe me, I know from experience!!!
Have a nice day!!! }:^{)~

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

By jwright650 (*****)

Date 06-17-2004 01:46

Hi SS,
So you have taken the exam, well, how do you think you did? I trust all the studying paid off. That exam isn't quite the walk in the park that some people seem to think it is. I sorta get the impression from several posts on the forum that Jim hasn't been exposed to that exam yet.
I'll be watching for your name in the back of Inspection Trends with all the new CWIs.
John Wright

By ssbn727 (*****)

Date 06-19-2004 18:07

Hi John Wright!!!
How's my Friend from Virginia doing these days?
To answer your questions; I believe I did well in the fundamentals and the practical parts... The Open book was not as easy as some would like to think being that after all, you have the book in front of you so, it should'nt be so hard to find the answers for the questions right?
Well, let me just say that it felt like I was being "slow roasted in a crock pot" during that part of the exam.
At first, I felt as if I'd been paralyzed with so much fear that my brain just froze for about what seemed like ten minutes yet in reality, I was only three!!! How it happened remains a mystery but, as soon as I prayed for release from this bondage, all of a sudden the lessons learned from the practice sessions in the seminar on how to navigate the D1.1 2002 code book kicked into focus and "I was off to the races"...
The questions that I somehow managed to answer while I was paralyzed were reviewed once I finished answering all of the other questions, and 2 of them were so far off from the original answer that I had to laugh at myself!!! In essence, As soon as I replaced my fear with faith, I was able to take control of myself, focus, and fly through the book with enough time to review every question in the open book part of the exam with time to spare.
As far as the other two parts, I appreciate all of the help you provided me to study ahead of the exam and it showed as I flew through those parts with confidence!!! I believe I did real well in those two parts because of your help John and I wo'nt forget that!!!
I think I did fairly well in the open book part also but then again, I believe I had some help from above on that part of the exam!!!

All in all, I learned alot in the seminar and without it, I seriously doubt that I would've done as well as I did!!! Especially in the open book part!
a little less than six weeks to go before I hopefully get my results back from the AWS so, We'll see!!!
Anywho, JW, I'll be writing from the Dominican Republic the next time I'm on the forum... It's been a long time since I've been there but, I plan on making up for all those years of not visiting my mother's country and rediscover all that it has to offer so, Adios Amigo Y Dios te bendigas!!!!!
(Go with god my friend, and may he always bless & protect you)

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

By vonash

Date 06-20-2004 02:02

Welcome to the club. Although, you were already the "man".
Best of everything to you and yours.
regards,
Vonash

By Lawrence (*****)

Date 06-20-2004 13:20

Mighty Submariner!

Congrats

Bon voyage

Benedictus!

Lar