RT on Pipe -Material Thickness above 19m

By pipewelder_1999 (****)

Date 03-16-2006 13:45

I would check with the engineering organization on the project or within your own company for the applicable documents. They should be available for your review if you are performing the RT.

By tito

Date 03-16-2006 13:57

B31.3 - look at para. 341.3.

Ask you client to explain his reasoning for it not being acceptable. Tell him to prove to you where it states these requirements.

By Shane Feder (****)

Date 03-17-2006 00:14

As has been mentioned on this forum many times before the codes contain guidelines.
The client can add any additional inspection if they like but it must be reflected in contract documents, they can't come in halfway through the job and change the goalposts,
Regards,
Shane

By GANESAN NALLATH (*)

Date 03-20-2006 16:40

Hi Friend
Thks for the help
For P3,P4,P5 Materials - Examinations shall be carried out
after PWHT- It does not specify RT shall be perforemed after PWHT
But for P1 -Carbon Steel - Not mentioned in code - That means
RT can be performed prior to PWHT followed by Hardness Test and MPI/LPT unless it is a contractual requirement
Pls advise if I'm correct
bye
ganesan

By NDTIII

Date 03-25-2006 04:27

[deleted]

By GANESAN NALLATH (*)

Date 03-28-2006 19:11

Hi Friend
My Real Concern is
Am I complying to Code for P3,P4,P5 Materials where RT performed prior
to PWHT the followed by only Hardness Test and LPT/MPI?
But the Code call Examination shall be performed after PWHT

Also advise if anyone have come across drastic change in the Weld Qulaity AFTER PWHT compare to BEFORE PWHT.Any articles on that, pls
send me
Thks for all the help

By NDTIII

Date 03-29-2006 04:12

If your Design or Engineering Documents specifically reference Heat Treatment for P-No.s 3,4 & 5 materials in accordance with Paragraph 331.2 & 331.2.1 and state that examination prior to heat treatment for P Nos. 3, 4 & 5 materials is acceptable, then ok. But I doubt it.

If not, and you are performing NDE prior to PWHT for P-No.s 3,4 & 5 materials and not after final Heat Treatment, then yes, you are in direct violation of the code.

Look at B31.3 Section 341.3 "Examination Requirements".

Then go to 341.4.1(b) (1). It requires "Radiographic Examination" for circumferential butt welds under "Other Examinations".

Paragraph 341.3.1 requires these examinations be performed prior to initial operation.

341.3.1(a) requires the Examinations be performed after any heat treatment for P Nos. 3, 4 & 5 materials.

I'm afraid your client is right. You are not complying with ASME B31.3 or normal engineering practices.

By GANESAN NALLATH (*)

Date 07-15-2006 17:13

Hi Friend
Recently I've taken RT before and after PWHT and RT Films reviewed and no change noted on film after PWHT. I've shown to my client. He still insist on complying to code. I would appreciate why B31.3 is has made as an mandatory requirement to do NDE Examinations after PWHT - ANY THOUGHTS ON THIS, PLS.

By NDTIII

Date 07-17-2006 13:25

It only requires NDE after PWHT for P-No's. 3, 4 & 5 materials. P-1 doesn't matter. Not enough residual stress to worry about it.

By andy

Date 07-17-2006 11:17

Many of the low alloy materials, but P5 in particular can suffer from reheat cracking due to the heat treatment under certain circumstances. This is why it is necessary to inspect after PWHT.

http://www.twi.co.uk/j32k/protected/band_3/jk48.html

Andy

By GANESAN NALLATH (*)

Date 07-18-2006 20:05

Hi Andy, Thks but have any one actually come across reheat cracking or other dicontinuity elongated to defect level. If so can you guide to these website. I want convince my self that it absolutely very important to do NDE AFTER PWHT,as RT very time consuming thus very costly especially doing RT twice. Thanks in advance

By GRoberts (***)

Date 07-18-2006 21:00

I have seen RT defects after PWHT that were not there before PWHT. It does happen occasionally, but seems to be very material dependant. I can't remember it happening on carbon steel, but do on 5Cr steel, as mentioned, and Cr-Mo-V steels. It also happens on materials that require rapid cooling (such as quenching in water).

By hogan

Date 07-18-2006 21:40

i have seen welds (& base metal ) crack after pwht, and after galv.

By andy

Date 07-19-2006 08:25

Yes. That's why NDT is specified after PWHT for these materials. Here's another reference on the web that state that reheat cracking can occur during PWHT.

www.cnea.gov.ar/cac/endye/glea/trabajos/ferraresi.pdf

Good practive with these materials is:

NDT before PWHT to ensure the weldment is free from defects related to the welding process, then you can fix these before applying a PWHT (and incurring the cost of the PWHT and having to go through several PWHT cycles which will affect properties and may invalidate your PQR).

Then PWHT. The PWHT MAY introduce metallurgically induced defects (reheat cracking) which is why the code states that you should NDT after PWHT. Note that things like grain size, residual elements and other factors mean that reheat cracking may or may not occur, but given good welding practice and control it is unlikely that you will see any changes before and after PWHT.

After PWHT NDT again. There will be no process induced defects (you will have identified these before PWHT) and consequently any defects will be as a result of the PWHT.

Andy