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Up Topic Welding Industry / Technical Discussions / P91/P92/X20 UT at RT before PWHT
- - By MM Date 05-26-2008 06:03
I would like to raise the following observation; at above certain thicknesses the performance of UT and MT on P91/P92/X20 on girth/butt welds, when they became to RT (room temp.) after welding completion, would give any advantage or disvantage? It would be wise or not?! I would like to see all of you IWE/IWT/IWS/SCWI/CWI/Metallurgists placing here your points of view, regarding technical/behaviour of these special materials versus NDE before PWHT. Many thanks in advance, MM
Parent - By js55 (*****) Date 05-27-2008 14:16
Many specifications for those materials will require NDE after PWHT since PWHT can expose and/or enlarge existing cracks.
The general idea to NDE before PWHT is self protection. If repairs are necessary you want to know about it before stress relief. Otherwise you will have to cook it again after the repair.
And this would be the case at any thickness.
Parent - - By 3.1 Inspector Date 06-03-2008 20:02
Hmmm
Most codes requires "NDE to be performed after any PWHT" execpt if it is for environmental reasons (for example in plain CS)
On top of the code requirements, re-heat cracking is a know factor.

P91 is susceptible to SCC in the "as welded condition"

NDE before PWHT can sometimes be a good idea, saves you to do PWHT twice - in case of weld defects.

API/CSWIP Inspector :)
Parent - - By js55 (*****) Date 06-03-2008 21:12
If I may.
Code requirement for NDE after PWHT?  Help me out here. Which codes?
31.1? 31.3?
And not to be too dramatic, but if Grade 91 hits service without PWHT there will be far worse problems than SCC. Like, Booom!!!!
Parent - - By 3.1 Inspector Date 06-04-2008 06:45
EN-13480 and several Japanese codes....you americans think you are the center of the world
Holy crap, guess you had a bad day in the office.....

EOD
Parent - By jon20013 (*****) Date 06-04-2008 07:57
3.1 Inspector you happen to be in an American Forum, please restrain your personal opinions regarding nationality as they are inappropriate and will not be tolerated.

Now then, for myself personally, I NEVER go to PWHT without doing info NDE / NDT for the very simple reason mentioned before and above.  Regardless of what the code says, it's always permitted to exceed code, hence, for me anyway, it's a before and after NDE.
Parent - By jrw159 (*****) Date 06-04-2008 12:01 Edited 06-04-2008 12:37
AWS-AMERICAN Welding Society :-)

While we here on this forum invite anyone of any nationality to join in and participate, you will find out very quickly that bashing the good ole USofA will NOT be tolerated by very many on this site. We try our best not to speak badly of other country's in general, short of discussions concerning the quality of material that may be utilized. IE Steel from China. And notice that I have the respect to at least capitalize the name of the country.

I do not know what brought this comment from you out in the open, and I really do not care.

From one PROUD American,
John R. West

OH say can you see, by the dawns early light. What so PROUDLY we hail..........

EDIT: For political correctness and spelling.

BTW-Wait for it, wait, wait........
Parent - - By js55 (*****) Date 06-04-2008 13:05
3.1,
I suppose my mild sarcasm was deserving of some equal retort. Never hurts to stir things a bit.
But attacking Americans???
A little over the top. Especially considering that many in this forum that are based here in the US (myself included) have been involved in the construction of facilities, pipelines, and such all over the world that were still governed by American codes. API, ASME, and AWS. Your point about European and Japanese codes are well taken, though globally the American codes are far and away predominant. So it would be helpful that when you are in discussion in an American forum about codes globally dominated by American codes it would be helpful to specify when taking exception.
Parent - - By 3.1 Inspector Date 06-04-2008 14:08
All points well taken....
Still dont change my mind though :)

I am well aware of the American codes - just went through my second API examination today :)
Parent - By jon20013 (*****) Date 06-04-2008 23:49
Gents, it's not only American bashing but ANY bashing of nationality, etc., is just not tolerated.  We're an open forum and as such, we need to maintain our level of professionalism.  Thanks all for understanding! :)
Parent - By Ringo (***) Date 06-06-2008 13:34
Because we are.
Parent - - By Jim Hughes (***) Date 06-06-2008 11:10
js55,
B31.1 2007 is now requiring NDE after PWHT. B31.1 was silent until 2007. Was considered SOP by those that were doing alot of P91 before 2007 came out.

Concerning other NDE before PWHT. We are starting to use Phased array before we go into PWHT as an INFO only step. Trying to get that warm fussy before we cook it.

Thanks
Jim
Parent - - By js55 (*****) Date 06-06-2008 13:25
Jim,
thanks
I don't have a 31.1 handy. Is it requirement for all materials or just those subject to heat treat cracking or temper embrittlement?
Parent - - By js55 (*****) Date 06-06-2008 14:28
Jim,
What paragraph of 31.1 will you find it?
Parent - By js55 (*****) Date 06-06-2008 14:31
Like I said, I can see it for materials subject to heat treat cracking or temper embrittlement (or for some alloys in greater thickness-meaning they will spend more time in the sensitive temp ranges) but its overkill for most alloys.
Parent - - By Jim Hughes (***) Date 06-08-2008 01:23
js55,
its found in paragraph 136.4.1 of 2007 B31.1. I tried to attach a B31.1 PDF but failed to do so.

The following is taken from the above mentioned paragraph.

"NDE for P-Nos 3,4,5A,and 5B material welds shall be performed after PWHT unless directed otherwise by engineering design".
Jim
Parent - By 3.1 Inspector Date 06-08-2008 17:43
:)
Parent - - By js55 (*****) Date 06-08-2008 18:54 Edited 06-08-2008 19:11
Jim,
Thanks
Interesting though. They did indeed limit it to those alloys susceptible to temper embrittlment or heat treat cracking, which in my opinion is a good thing, and consistent with the conservatism of ASME, but I noticed in your quote (and I know your quote is a limited extraction), it does not say which NDE specifically. Is this included in the remaining paragraph? Is it left up to the specifying party, the fabricator, or is the code silent on this point?
After all 31.3 has had hardness testing (an NDE method)after PWHT in place for some time. For the purpose of verifying PWHT. This is not what is a concern in the context of the original post. P1 is conspicuously absent.
I gotta get my hands on a more recent version of 31.1.
Also, the NDE of choice for concerns about temper embrittlement and heat treat cracking of bainitic and martensitic materials (the materials listed in the orginal post) has been RT.
So UT would of course be of great value. Perhaps even more so. PT, MT, hardness testing are almost useless for the concerns involving the materials in the above posted paragraph and the original context.
And I also noticed the 'Engineering" "exception" at the end which almost renders the paragraph a recommendation. In other words, you have to do this, unless you don't wanna.
If you have concerns specific to Grade 91's, Grade 92's, and other CrMo's, or low alloys, just saying NDE ain't gonna get it done. You need RT/UT.
So clearly I've even corrected myself on the NDE after PWHT recognizing 31.3 hardnesses, I was assuming RT or UT due to the alloys the original question was framed around.
Parent - - By Jim Hughes (***) Date 06-09-2008 12:37 Edited 06-09-2008 15:40
js55,
I wish I new how to attach a file to these post. Maybe someone can walk me through it. But the NDE requirments are the same and are referenced in Table 136.4. So if you have an old B31.1 the table should be the same. If its not covered in Table 136.4 then only VT is required. All this new requirment is saying is that now for these P-Nos you will do whatever NDE Table 136.4 says you will do AFTER PWHT.

As far as the Engineering Exception. Most engineers that I have worked with will not override a code requirment. If they do then they better have some very good engineering data to back it up and be ready to testify in a court of law. PE stamps are worth a lot more to an engineer then gambeling on something like this. When a code gives cover for an engineer, for the most part they are going to take that cover.

Thanks to Stephan I attached a B31.1 2007 that covers NDE and PWHT.
Thanks
Jim
Attachment: B31.1revision.pdf (131k)
Parent - - By Stephan (***) Date 06-09-2008 13:02
Jim,

please let me try to help, by attaching a document that the appreciated John Wright has attached for me, at that time as I was the one who needed help with this.

Best regards,
Stephan
Attachment: John_Wright_Attaching_pdf_s.jpg (123k)
Parent - - By Jim Hughes (***) Date 06-09-2008 15:39
Stephan,
thanks for not openly calling me an iddiot:) 

As we say here is Texas, If it were a snake it would have bitten me. I don't know why I did not see that before.

thanks for your help.

Jim
Parent - By Stephan (***) Date 06-09-2008 17:36
Jim!

I bow my head before you, your knowledge and twice... since you're from Texas!! :-):-):-)

Best regards,
Stephan
Parent - - By js55 (*****) Date 06-09-2008 18:36
Jim,
Is idiot to be spelled with two d's?  :)

He ventures (speaking in the third person) to make a joke of a colleague while recognizing that he himself was arguing in this very same thread that there was no NDE after PWHT while at the same time recognizing at the very least hardness testing in 31.3.

I think its contagious.

Stephen, your only hope is to run.

Is it friday yet?
Parent - By Jim Hughes (***) Date 06-09-2008 22:34
js55,
the second d is for emphasis on the trait. As brain cell count goes down spelling errors go up. :)

Thanks
Jim
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