Welding defects in structural steel welding (Overhead Crane) 5

[metboss]

Hi All,

We have supplied Overhead Crane to our customer directly from our OEM/manufacturer facility(manufacturer origin- Europe) and during in-receipt inspection by Client QC, it's been found with weld defects (porosity, spatter,incomplete penetration) on some areas of fillet weld joint(Cantilever/Girder weld joint). At the outset, client rejected our Crane and asking for corrective actions. We have contacted our OEM and obtained all documents. It's noted that they used EN standard for welding and used only 10% NDE (MPI & UT).
Now as a corrective action, we need to repair the fillet weld joints; but, OEM is not ready to send their welder to our facility (cost impact: Europe to Middle East).

Now I have below concerns:

1) Can I use local sub-contractor welders with OEM's WPS/PQR to repair the defective welds ?
2) Or do we need to qualify these local sub-contractor welders to OEM's WPS ? OEM's WPS is based on EN standard and not as per AWSD1.1
3) Or can we utilize any AWS D1.1 qualified sub-contractor welders ?

Please advise.

 

[metengr]

Now as a corrective action, we need to repair the fillet weld joints; but, OEM is not ready to send their welder to our facility (cost impact: Europe to Middle East).

I would not take this responsibility on if I were you. As a client, I would not accept the current crane and have another sent in its place by the OEM if they are unwilling to repair this because of travel cost.

 

[EPCI-Steel]

metboss,

I don't care if the MFG document specifies only 10% NDE, Visiual Inspection is type of inspection as well. And somewhere in the OEM's QC specifications it will state 100% visual inspection. Often noted as VT. In most fabricators the welder foremen are certified for VT and are supposed to provide the 100% visual inspection to satisfy the requirement. The requirements for visual inspection apply between weld passes in a multi-pass weld, not only to the finished weld. Spatter is not usually considered a defect, just poor workmanship. If the porosity is open to the surface of the finished weld it should have failed visual in the factory. If the porosity is in a multipass weld it probably should have failed visual inspection at the factory. Really only spherical porosity in large single pass welds (SAW) is not evident to a visual inspection.

Now you and your client need to understand that almost all welding codes do allow for some defects. The code that the item was manufactured to will tell you what the type, size of, length of, and spacing of these defects is allowed to be, and you have to accept that unless you or your client specified in the contract a higher standard than what the fabricator states in their specifications.

If the MFG did not in fact meet the standards of the welding code they specify, they have an obligation to correct the non-compliant welds.
If they did in fact meet the requirements of the welding code, you (or your client) own the crane and you can do what ever you want with it, including having it repaired according to AWS D14.1. You need to verify what the steel the OEM used as it most likely not a grade listed in the AWS standard, and do some calculations to determine that the Carbon Equivalent (CE) of the weld deposit meet the criteria of the code.

If your selected repair shop has PQRs and WPSs that meet the requirements of the AWS D14.1 and satisfy the strength and CE requirement with the steel to be welded then you are good, otherwise you will have to qualify new weld procedures for the steel / process / electrode / code of your specific application.

 

[dik]

I hope you haven't paid the supplier.

You need a report from a welding engineer to confirm that what you received was not what was contracted.

You then advise the supplier that the crane is non-compliant and that they have to undertake remedial action. How they do it is their issue.

If they are not prepared to do this, then you have to undertake the work using local labour, or whatever. They should be responsible for all costs.

Once the remedy has been undertaken it should then be re-inspected. With a crane, it may require additional certification.

Keep track of all time and costs involved.

Good luck...

Dik

 

[EPCI-Steel]

metboss,

I just realized I did not answer 2/3 of your questions.

Yes you can use any competent welder if you have them qualified with the OEM's Welder Procedure Qualification (WPQ) that covers their WPS(s) for the repairs.
As others have stated I would not suggest taking this responsibility on yourself if it can be avoided, the manufacturer should pay for the welder qualification and the repair, and you should keep the liability on them.

 

[kingnero]

Overhead cranes are subjected to codes and regulations. What you describes is definitely not compliant with those codes (whatever code is applicable). You have reason to ask for a solution. The mfg should cover this.

If this comes from an european mfg, EN 13001-3-1 states that quality level C according to EN ISO 5817 should be applied for load carrying welds on cranes. Apart from this standard there's also EN 1993-6 (crane supporting structures).

---

http://be.linkedin.com/in/fusionpoint

 

[metengr]

I absolutely disagree with the comments above about undertaking weld repairs using a subcontractor on a crane that can result in property damage and loss of life. To me this is about responsibilty and should something happen the crane manufacturer has this obligation for repair. Arguments about travel cost are ridiculous.

 

[EPCI-Steel]

metengr,

We do not know what the actual state of welds on the supplied equipment are.
10% NDT inspection of welds on newly fabricated crane seems absurd to me be based on my experience, I would have expected 100%.

But there is so much unknown here I was trying to cover all possibilities and answer the question asked.
I'm sure that we have all encountered through the course of our work suppliers that, once paid, are off the job and the rest is your problem.

I have also encountered clients with totally unreasonable QC specifications, such as allowing no defects of any kind in essentially non-loadbearing weldements. I have encountered QC inspectors that make a big deal out of nothing and totally incompetent QC personnel who would OK welds with 1/4" piping porosity in padeye connections. I have had jobs where lack of fusion in the root of 4" thick primary structure CJP welds was disputed by two different UT technicians, one saw LOF at the root through half the joint, the other saw nothing. I was on a job where we flat rejected a lift and set contract, which was already signed, because the quality of the welding in the structure was so terrible. It was all signed off on by the client and the fabricator but there was still slag on the welds and you could see the porosity and LOF (or terrible weld profile that most likely indicated LOF) at the weld toes through the paint. I'm saying crappy weld inspection goes both ways, it may be a newly minted engineer seeing shadows or it might be terrible QC from the fabricator, we don't know. The fact that he had spatter listed in his defects leads me to believe it may be more of the former than the latter, but how am I to know?

If they have already taken possession of the equipment, paid for it and the OEM disputes the claim and refuses to make it right what are they to do?
Delay the project because of one piece of equipment? Buy a new crane while you fight it out with the OEM?(cant just buy one of those off the shelf at Lowes) Or do you make the repairs in the most professional manner possible, perform proper NDT and recertify the crane and get the job done to satisfy your client so you can get paid? You take your lumps and don't ever do business with that company again, and maybe provide your own QC at the fabricator next time.

 

[kingnero]

10% NDT inspection of welds on newly fabricated crane seems absurd to me be based on my experience, I would have expected 100%.

Seems normal to me. 100% VT is a prerequisite of course.
Please refer to the table below from EN 1090-2. A crane, although the bridge girders do not fall under this standard, would typically fall under execution class 3 or EXC3. Supporting structure (columns and runway beams) do fall under this standard, where considering fatigue makes it EXC3, smaller/simpler structures are EXC2.

---

http://be.linkedin.com/in/fusionpoint

 

[EPCI-Steel]

Kingnero,
You obviously have worked with this before, thank you for your informative contribution. I myself work mostly in structural oilfield projects, mostly AWS D1.1 stuff, but I do know the D14.1 specification for cranes is mostly the same. And client specifications usually control our inspection requirements, 20% NDE is about the lowest I've seen with 100% being the norm for primary structure, and based on that I would have thought a crane would be 100%. So thanks, you learn something new everyday.

 

[dik]

further to metengr's comments... if you apply a weld, you've bought the crane and the supplier is 'off the hook'.

Dik

 

At the end of all this, strike the vendor from your Approved Supplier's List. Any product at all (much less an overhead crane) should never have been shipped with the obvious and extensive visual weld defects you describe.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[DekDee]

metboss,
If you ask for assistance you must supply the code you are working to (or what was required for your purchase) which will help identify the acceptance criteria.
You cannot state you have all these "defects" (spatter, porosity and LOP)- they are not defects unless they do not comply with the specific acceptance criteria (which we do not know).
Spatter is not a defect - it is something that is undesirable for aesthetic reasons. - usually noted it is not acceptable in project specifications but you haven't mentioned these.
Porosity is another that is not considered a "defect" unless it is that bad it masks other defects from being detected. Again, surface porosity may be rejected for surface treatment reasons but this will be in your project specifications - not the code.

As someone who has spent the best part of twenty years in Asia signing off heavy structural items prior to shipment, you and your client have got what you paid for.
Who from your company or your clients signed it off as code-compliant prior to shipment ?

Just on this subject.
Had some 42" Duplex valves supplied for Sub-Sea with defective welds on the hydraulic tubing - manufactured in Italy and installed in Malaysia.
I was the Clients Rep and rejected them all - the Contractor agreed with me and when NDT reports were found to be "missing" the decision was made to install new tubing with all the subsequent welds.
Sub-contractor had to fly a welder from Italy to Malaysia, qualify a new WPS (long story) and then qualify to that WPS, then perform all the subsequent welds.
Big, big money down the drain (and huge delays to the schedule) just because the Contractor and the Client wanted to save money by not sending someone to Italy to inspect prior to shipment.
Regards,
Shane

 

[dik]

Who from your company or your clients signed it off as code-compliant prior to shipment ?

...signed it off as code/spec-compliant... BTW, a great posting...

Dik

 

[weldstan]

In terms of repairs to cranes and inspections, I heartily agree with both netengr and DekDee. Do not initiate repair without full buy in from the manufacturer. Have multiple purchaser inspections during manufacture and be fully aware of what is a true defect or an acceptable weld flaw.

We had a similar incident where our inspector was only authorized for a single visit to the crane manufacturer which resulted in positive findings of proper work being done but this only represented a single snapshot of the work performed at that moment. Subsequently the manufacturer made changes to its assembly and welding methods that resulted in severe cracking, undersized welds, lack of fusion, and weld slugging with rebar, only detected during field assembly and initial repair. Localized weld repair was not easily accomplished due to the high residual stresses imposed by the manufacturing techniques employed and only resulted in more cracking, even with full input from the manufacturer. In many cases full disassembly of the components was required to effect the repair. Because the manufacturer and end user was in the USA, litigation was costly but in the end the manufacturer paid for the repairs, the costs of the User having to rent cranes to replace those being repaired in order to meet project completion requirements and court costs.

 

[DekDee]

Another concern is if the surface welds visible are of a poor standard then it does not invoke confidence in the "hidden" welds - internal stiffeners / braces etc that must be inspected prior to being boxed in.
I recently turned down a request to inspect and sign-off a major structure in China that was destined for Canada because the only inspection was a final (1-2 days) visual inspection.
If they are not interested in surveillance during fabrication I am not interested in risking my reputation by signing something off with no idea of fabrication history.

 

[EPCI-Steel]

DekDee,
Smart move. We had a project that was done in a Chinese shipyard with our own team of local (mistake #1) and European QC inspectors that were supposed to inspect every connection with visual and appropriate NDT. After taking delivery of the modified vessel, weld deficiencies in the typical hard to reach places show up eveytime that vessel comes into a shipyard, including a major repair undertaken in the Straight of Singapore between jobs. That really was fun though (from a purely personal POV), we heeled the vessel to the point where it was hard to walk in order to get the area to be repaired out of the water.

 

[gtaw]

DekDee offers some sound advice. The deficiencies are only considered defects if they exceed the limits imposed by the welding standard. An inspector cannot call a discontinuity a defect based on his personal opinion, it must be based the criteria provided by the applicable welding standard. One cannot reject a weld for excessive undercut if the applicable welding standard has no criteria listed for undercut. Likewise, one cannot reject spherical porosity if the project specification cites AWS D1.1 for the simple fact that D1.1 only list acceptance criteria for piping porosity. Spherical porosity is not an attribute addressed by AWS D1.1.

Who is at fault? It depends on the project specifications and what it contained regarding the applicable welding standard and any exceptions taken to that standard. If the Owner failed to provide sufficient information in the project specification, the courts in the US will side with the contractor.

Years ago I was asked to inspect a number of welds the Owner found to be deficient. I reviewed the project specification and under the heading of welding it simply stated "all welds shall exhibit first class workmanship in accordance to AWS standards."

My client, the Owner, didn't have a leg to stand on because the project specification didn't state what AWS welding standard was applicable and I have never seen an AWS welding standard provide criteria or define what "first class workmanship" is. It was a case where the Owner's Engineer fell flat on his face. The Owner repaired the deficiencies, but he had to pay for the repairs. When asked, "Is this a good weld?" My response is, "Compared to what?"

The project specification must be clear and unambiguous. It isn't over yet. The Owner must also enforce the terms of the contract. He cannot "cherry pick" what portions of the contract are enforced. The enforcement is enacted by providing competent oversight, i.e., verification inspection. The contractor is responsibility for quality control, but it is in the Owner's interest to exercise a reasonable level of quality assurance.

Best regards - Al

 

[metboss]

Hi All,

I really appreciate all of this feedback.
The latest update is that OEM QC Rep. will be visiting us to re-inspect all defective weld joints. Meanwhile, our client has requested us to submit the method statement for proposed repair work.
I’ll keep you updated soon.

Again, Thank you all for your inputs.

 

[gtaw]

I'm not sure what a method statement is, but if it involves telling the manufacturer how to repair the faulty welds, tread carefully or you may find yourself liable for any future problems.

It may be prudent to have the crane system inspected by a third party to identify the deficient welds, but insist the manufacturer devise a repair plan to correct the unacceptable welds. The manufacturer should shoulder the responsibility for the method and means of facilitating the corrective work.

Best regards - Al