PT requirement on root pass welding

[Jorge Hevia]

thread725-290810

Dear all, in reference with the above subject, please do note that the NDT guy can be right by requesting PT on a root weld.

It is true ASME doesnt require such, but it is equally true that additional standards such as NACE MR0175 or NACE MR0103, referring to NACE SP0472 welding procedure may require this on all root welding, specially when doing WPQ/PQR.

Upon discussion and negotiation with your customer you may or may not override some or all of these requirements depending on the criticallity of the service you are handling and the expected media (HIC,SCC,SCCA...)

Best regards.

 

[kingnero]

If this (root pas X-ray) is in advance agreed upon, all parties can and should do whatever they want.
If it is not agreed upon or in writing, and an NDT guy is proposing something like this, I agree with most of the posts in the 2011 thread.

 

[Jorge Hevia]

Of course Kingnero,

The point here is to know where this requirement comes from.

If it is agreed beforehand, no problem, but later on some party would have to bear the consequences if corrosion damage appears during operation, and as consequence of that an accident happens.

We are dealing with the limits of practical operation vs high specs requirement.

Best regards

 

[kingnero]

Yes, I too wonder where the requirement comes from (apart from the codes you mentioned before).
Most likely defects in a root pass are cracks/fissuration, for which PT of MT is much more suitable to detect.
If you have porosity (for which RT is indeed the best solution to detect it), it is likely that the pores comes to the surface. Again, VT and PT/MT will most likely tell you the problem. For tungsten inclusions etc. is RT the only sulution, but if you're fleet welding or migging the root this isn't applicable.
I regularly have this kind of discussion with inspection parties. All inspection should be in line with the (welding) execution procedure and for the expected defects, but most are very experienced guys in NDT (or in procurement, or from the sepcification writing department) but know nothing about welding.

I wonder how others feel about this.

 

[DekDee]

I have been saying this on this forum for years and years.
If someone tells you to do something you are unsure of or do not agree with - do not come on an internet forum and ask for help.
Ask the person who instructed you - can you please reference the code/standard where this is noted ?
If it is noted in your project specifications (which we are not privy to) and you have not reviewed properly then nobody can help you.
Good luck with resolving,
Cheers,

 

[r6155]

Some causes:
1) excessive gap
2) no preheat and postheat
3) welding from one side
4) Shrinkage of the hot weld metal as it cools

Regards

 

[dik]

I appreciate the dialogue that comes from the questions.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Jorge Hevia]

@DekDee

As the subject of the post indicates, this is just a hint.

I am very clear about these requirements and where do they come from, also for which service they are applicable for.

Unfortunately, most customers/end users don't understand the specifications written by i.e. Woods (former Foster Wheeler) and it is quite difficult to explain to someone which is not familiar with the topic, the materials corrosion processes involved in the details of requiring this, yet more difficult to explain to someone in your own team (i.e sales people).

To understand the processes involved you need at least some materials science knowledge and also process knowledge, usually given at the university, and you cannot send the people to the university to learn at this stage of life (they just are not interested in)

Now I am in charge of a manufacturing company, so the discussion of these topics with our sales and customers is a daily topic. Discussing with our manufacturing people is even weirder, as they do not understand why they have to do this supposedly stupid action for which you are not going to see any evident return during the warranty of the equipment (typically 2 years), but later on in the life of the unit down 10 years up to the 25 which is the expected life of the item.

So, regarding of the original topic about an NDT guy requiring PT on a root weld, could be specified or just because of his own initiative. In any case, many people backfired about what this guy was doing, and I can only support him if it is specified somewhere.

To wrap up, if you expect corrosion service as per NACE consideration, further requirements on ASME are needed. NACE tells you to do PT which is usually enough to detect any small crack, which is the main aim of this, in order to avoid later on Hydrogen Induced Corrosion or Stress Corrosion Cracking. Doing anything beyond the requirements its expensive and usually there is no need for it.

Just to shed some light on this topic later.

Cheers

 

[r6155]

Crack is not allowed on any service.

Regards

 

[dik]

Not so good for transferring tension or shear, I guess...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[david339933]

If I am performing procedure qualification, there is no way anybody is spraying anything on my root pass. Hardness survey can be done after welding.

 

[r6155]

The crack can start to propagate suddenly (when the temperature is low and depends on the material), and can be a problem even during the hydrostatic pressure test.

Regards

 

[Jorge Hevia]

@r6151

Sorry for my ignorance, but as I know ASME allows certain cracks size and number in welds depending on the service and class of inspection. Correct me if I am wrong. Here we mostly cover all other non ASME requirements such as NACE ones, more stringent than ASME.

@David339933

Good luch with the WPS/PQR/WPQ approval with your customer if NACE SP0472 (required with NACE MR0175/MR103)is enforced. Your WPS will be rejected. Most people doesnt realize NACE MR 0175/0103 is not about hardness control only, and involves much more. Of course you can agree with customer not to enforce the root pass NDT, but whether they will agree or not, thats another story.

Best regards

 

[david339933]

Unless something drastic has changed in the 2020 edition of SP0472, there are no NDE requirements for root passes...and therefore nothing to enforce. NDE of the root pass of a P1 material is the least of my worries on procedure qualification.
Also, you think cracks of any kind are acceptable?

 

[david339933]

I should also state that MR0175 does not mandate SP0472.

 

[Jorge Hevia]

@david339933

Yes, seems you are right regarding the NDE requirements for root passes. I had missed it with most customer specifications (like Shells, Aramco..) which always refers to NACE standard, my bad here.
Regarding the cracks, I agree with you that no visual crack is acceptable, and this is why they want to use PT, to see any one that you cannot see with the naked eye. In any case, if you can skip that part with your customer, it is way more convenient for production, otherwise its a burden.

Finally, although MR0175 does not mandate SP0472, it says that MR0175 is applicable to all equipment in where SCC is a worry to consider (Scope paragraphs 2 and forth). Further reading on MR103 on scope also states that that standard is applicable to any equipment in where SCC is expected to happen, so indirectly MR0175 and MR103 are referring to each other, and in the end to avoid SCC with ASME P1 materials, SP0472 compliance is mandatory in MR103.

From my point of view, MR0175 refers only to materials requirements selection and MR103-SP0472 to fabrication in conjunction with ASME, so they go together.

Of course you can keep endless discussions with customers about which one applies (MR0175 is way simpler than MR103) although for me if NACE is applicable, automatic discussions are in place always, doesn't matter which the standard to be discussed)

 

[david339933]

There should be no "endless discussions". MR0175 deals with upstream production and MR0103 deals with refineries. You came on this site with the sole purpose of contradicting a previous thread as though you were well versed/experienced in NACE requirements. You have done more harm than good.

 

[weldstan]

Your original question involved an "NDE guy" being correct in requiring PT of the root pass. The answer is NO. The Engineer/Owner specifies in the contract specifications whether or not it is required and this can include reference to other national/internatioal standards and recommended practices.

 

[r6155]

Be careful, ASME is a CODE and NACE is a STANDARD.

Regards

 

[Jorge Hevia]

@david339933

I am so sorry you see that way and I still disagree. If this discussion continues, it only demonstrates there is no agreement about this topic yet, which is in line with my last 14 years work experience worldwide in this.
Regarding the application of MR0175 to upstream and MR0103 to downstream, it makes no difference, as the corrossion effect is the same no matter where you apply it. Nowaways you can have upstream licensors/owmers asking for downstream specs to apply so this simplifiation to stick to is nonsense as of today.

@weldtan

Thank you for your reply. But still, what happens when as per a certified U1/U2 ASME company, you have the QAQC department isolated from the rest with full management support? ASME certified companies requires QAQC department to be fully independent and being able to stop any work at their discretion in case they think there is something wrong. Whether the guy is right or not, thats another story, but as per ASME whenever a QAQC inspector/person raises a NCR (because he is supposed to be qualified to do so in this position), all jobs are stopped, whether you like or not until NCR is closed. On a stamped job, ASME inspector will review as well the NCR and approve/close/reject as applicable. The NDE guy may had seen something others hasnt, and has the power to require additional tests of he is not happy with the result or suspects something.

@R6152

It is irrelevant for me whether ASME is a code to follow and NACE a standard when NACE requirements modifies ASME code basic requirements. Today, on ASME stamped units such requirements are defined as process requirememts, and AIs enforces as it were ASME code requirements (such as PWHT requirement)

I am glad to share my experience here even if some of you dont agree. Although you may it consider doing more harm than good, hope this discussion helps other people, whether you are negotiating a contract or executing a job, either from a process licensor or just a workshop.

Best regards