NDT and PWHT - ASME I / B31.1 6

[FernandoL]

Due to my little knowledge and also based on the need to use ASME I and ASME B 31.1 for the construction of a boiler and its power piping, in which items of these codes are defined the correct time to apply the non-destructive tests. In other words, before or after post weld heat treatment?

 

[DekDee]

Not wanting to seem rude but if you are building a boiler and power piping you better start reading the relevant codes.

 

[FernandoL]

Dear @DekDee, you were certainly not rude. you were correct.

I'm not actually building either the boiler or its power piping.

I am a professor of industrial quality and in preparing myself for these standards, I did not find in the content of them the determination of when to do the formal tests - before or after PWHT.

Just for example, in ASME VIII div 1 - paragraph UHA 33 (b) it is clear the definition of non-destructive testing (radiography) must be done after the PWHT for some materials

I also searched for ASME I and B31.1 code cases and interpretations and found no clarification on this topic.

That's when I sought help from the experts

All the best, thanks

Fernando

 

[r6155]

Fernando
You should read more DEEPLY because as a teacher you will have to answer many questions.
There are other NDE besides the x-ray.
Please read again ASME VIII Div 1, ASME 1 and ASME B31.1. The concept is the same. They are very clear.

Regards

 

[FernandoL]

Challenge accepted

I will read the codes deeply and post my conclusions

I will count on your help in correcting my reasoning

thanks a lot

Fernando

 

[DriveMeNuts]

Have a look at Section VIII UW-40 PROCEDURES FOR POSTWELD HEAT TREATMENT

UW-40(e) Postweld heat treatment, when required, shall be done before the hydrostatic test and after any welded repairs except as permitted by UCS-56(f). A preliminary hydrostatic test to reveal leaks prior to postweld heat treatment is permissible.

A hydrotest before PWHT amounts to stretching a pressure vessel to the extreme while it still contains a lot of residual weld stress and weld HAZ anomalies.

The pressure test also introduces "beneficial" residual stress. PWHT after the pressure test removes any beneficial residual stress.

 

[0707]

To avoid an unecessary PWHT it is a good pratic to make X ray before PWHT but defenitly after PWHT.

luis

 

[r6155]

@ DriveMeNuts's
Fernando (OP) is talking about NDE.
Hydrostatic test is not a NDE.

Regards

 

[DriveMeNuts]

Oops, my bad.

Where Radiography is required, UCS-56(e) and UHA-32(e) nudge you in the direction of doing volumetric (X-Ray) NDE before PWHT, however this is not mandatory. If you were to do it after and there is a weld flaw, then after weld repair, the entire vessel will potentially need to be re-PWHT'd.
X-Ray would only be required after PWHT if explicitly required by the code (i.e. UHA-33(b)).

Various clauses such as UHA-34 require surface crack detection after PWHT for specific materials and thicknesses.

So I guess the answer to your question: it depends on material and thickness, and that it is wise to consider surface and volumetric NDE before PWHT as an insurance policy against having to repeat the PWHT (even if you have to repeat the NDE again after PWHT).

There are even conditions where radiography can take the place of PWHT (Table UHA-32-1).

 

[r6155]

@ DriveMeNuts's
Fernando (OP) is talking about NDE before or after PWHT, not the need of PWHT
The service condition defines the material and then the need of PWHT.

Regards

 

[DriveMeNuts]

r6155, my post relates to whether NDE is required before or after PWHT as per the OP question.
The last sentence also points out that it is not as simple as whether NDE be before or after PWHT, as there are technicalities for some materials that allow the use of NDE to avoid PWHT.

 

[DekDee]

The OP is asking for information on ASME 1 & B31.1 - not ASME VIII.
ASME VIII was just used as an example.

 

[DriveMeNuts]

I'm not familiar with Section I, however a word search reveals that Table PW-11 specifies when volumetric examination is required after PWHT for specific welding processes, and can otherwise be before or after as per my last post.
As per r6155, all the codes are similar.

Two troll comments from DekDee in one thread. Is that a record?

 

[0707]

DriveMeNuts

There is no NDE which avoid to do or not to do a PWHT. PWHT is required by the material specification, is intrinsic of the qualty of the material.

Regards

luis

 

[r6155]

PWHT is not discussed, when to conduct formal NDE is discussed.
Table UHA-32-1 does not correspond to analyze because Fernando(OP) does not question how to avoid PWHT.

Regards

 

[DriveMeNuts]

Fernando does ask when to conduct formal NDE.
He also says that he/she has little knowledge of the codes. As a result, I have advised that asking if formal NDE is conducted before or after PWHT is too simplistic a question, because the presence of volumetric examination negates the need for PWHT in some cases.
For example, type 410 SA-240 plate requires PWHT by default.
However, when Radigraphy is introduced, PWHT is not required in some cases as per the following (from table UHA-32-1):

Postweld heat treatment is not required for vessels constructed of Type 410 material for SA-182 Grade F6a, SA-240, SA-268, and SA-479 with carbon content not to exceed 0.08% and welded with electrodes that produce an austenitic chromium–nickel weld deposit or a non‐air‐hardening nickel–chromium–iron weld deposit, provided the nominal thickness does not exceed 3/8 in. (10 mm), and for nominal thicknesses over 3/8 in. (10 mm) to 11/2 in. (38 mm) provided a preheat of 450°F (230°C) is maintained during welding and that the joints are completely radiographed.

 

[0707]

Prof. Fernando

What is your question? You are transforming this thread in a big confusion.Tell us clearly what is your doubt.

luis

 

[DekDee]

Drivemenuts
Not sure what " troll comments " means but I will say it again.
The OP is asking for information on boilers and power piping.
What does type 410 material on a pressure vessel have to do with that ?

Fernando,

Standard Designation: BPV Section I
Edition/Addenda:
Para./Fig./Table No:
Subject Description: Section I (1986 Edition, 1987 Addenda), PW-11, NDE Prior to PWHT
Date Issued: 12/15/1988
Record Number: BC88-393
Interpretation Number : I-89-14
Question(s) and Reply(ies):
Question: Does PW-11 require that NDE be performed on welds after they have been subjected to the postweld heat treatment required by PW-39?

Reply:. No, unless the conditions described in PW-11.2.2 exist.

PW-11.2.2 was removed in the 2004 edition and is now Table PW-11 (h)

PW-11.2.2 In addition to radiographic examination,
electroslag welds in ferritic materials shall be ultrasonically
examined throughout their entire length. This
ultrasonic examination shall be done following a grain
refining (austenitizing) heat treatment, if one is used.
If such heat treatment is not used, this examination shall
be done after an intermediate postweld heat treatment or
after the final postweld heat treatment.

 

[DekDee]

Fernando,
As for B31.1

131.6 Interruption of Welding
131.6.1 After welding commences, the minimum
preheat temperature shall be maintained until any
required PWHT is performed on P-Nos. 3, 4, 5A, 5B,
and 6, except when all of the following conditions are
satisfied.

I think NDE must be performed after PWHT on the materials listed above (by default) as pretty hard to get an RT film or a UT probe on something that may be 100-150 degrees C.

Hope that helps,
Cheers,
Shane

 

[r6155]

DekDee
You are some confused.
No relationship between “preheat” and “interruption of welding” with RT or UT
Please, read again “131 WELDING PREHEAT”

Regards