REPAIRS AFTER STRESS RELIEVING

Date 12-01-2008 06:21

qaqcmpm,

1.If there is a repair in SR completed joint (ASME B31.3), is it require to do SR again? (Pls provide the code reference)

Being able to assist on this forum is done voluntarily and we all try to help out as best we can but you need to get stuck into the codes and learn them yourself.
It is sometimes too easy to just post a question and let other people do the work finding the answers. You will not learn how to navigate a code without researching it yourself.
I went to the index - looked up "repair" and got 6 sections. The second one I got to was 328.6 Weld Repair stated "Preheating and heat treatment shall be as required for the original welding."
All of 2 minutes for me to locate the answer, but have you personally gained anything other than an answer - not really.
I have asked questions on this forum numerous times but only after looking and looking and looking and not being able to find the answer.
Now I consider myself proficient at navigating most codes but that has only come about through reading them over and over and over.
Hope the answer helped,
Regards,
Shane

By js55

Date 12-01-2008 14:15

"but that has only come about through reading them over and over and over."

I heard that.
Til your eyes are boodshot.

By qaqcmpm (*)

Date 12-01-2008 16:04

thank you Mr shane but my second question is not still answered? Even though I refer the code why I am asking this is to gain more informations and views to enlighten through more valuable inputs. And regarding my second question my client advises me to qualify the WPS with multiple heat treatment cycles. When the number of cycles increases hardness improves (reduces the hard spots/reduces the hardness) i.e. reduces the Tensile strength also. Any views?

By js55

Date 12-01-2008 17:38

Its not the cycles as much as it is time at temp. But also, keep in mind that it doesn't necessaarily always reduce hardness. It depends on the alloy. Some alloys will have secondary hardening reactions (those with V, Nb, can do this) that take place, though these reactions generally take more time than the more common MC type carbide precipitations which is generally quicker.
Also, carbon steels have been known to demonstrate a secondary hardening. This can happen if a microalloyed material has been downgraded to a carbon steel spec. Again, those elements that form fine stable carbides or carbonitrides (V and Nb) can be common culprits.
This is part of the reason thay T at T is a supplementary essential variable. Its more likely to effect impact toughness detrimentally more than it is tensiles and bends.

By G.S.Crisi (****)

Date 12-01-2008 17:36

Shane,
you've been somewhat rough with qaqc. Take into account that for those who live in first world countries (and Australia is one of them) is easy, or at least relatively easy, to get hold of a Code or standard.
For those of us who live in third world countries, it's not that easy.
In engineering school libraries you'll usually find old editions of standards and codes. This is because they're very expensive (we have to buy them in dollars with using our low value currency), and professors say (I'm one of them) that the important thing is to familiarize students with the codes and standards, have the students put their hands on them (codes and standards), know that they exist and learn how to read them. Knowing the details of the last edition isn't that important for students.
Few engineering companies and manufacturing shops have the last edition of every code and standard. In the most usual case, they've got the last edition of one (the one they use more) and former editions of the others.
Now, I'm speaking of Sao Paulo, the most important city of Brazil. The same can be said about Rio de Janeiro, where Petrobras is located. In other cities the situation isn't that pleasant.
Giovanni S. Crisi
Sao Paulo - Brazil

By 3.2 Inspector (***)

Date 12-01-2008 19:06

Giovani,

When a company engage them self on a construction project it is only fair to claim that they need the latest edition of the applicable code.
To me it looks like qaqcmpm is on a project, and not a student.

I think Shane gave the right answer here, however, I think it would be a fair question if he asked: What happen at additional time at temp, is there any metallurgical reason for the code to make it a E.V

Here he ask for a specific code reference, which could indicate that he did not look through the code on his own. (as Shane did for him in 2 minutes)

3.2

By Shane Feder (****)

Date 12-02-2008 01:16

qaqcmpm,
Have a look at this posting below or type PWHT in the search engine. A lot of questions asked on this forum have already been answered previously and it is just a case of going back and having a look.
jon20013 and js55 are very experienced with the metallurgical side of welding so you can take 99% of their opinions as gospel. The extra 1% is when jon has been partaking in a little Bundy rum ! LOL !!

http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=70948;hl=PWHT%20after%20repair

In answer to your question 2 - If notch toughness is a requirement you would have to do a second PQR as T&T becomes a Supplementary Essential Variable but if it is not a requirement then you are fine with your original PQR as T&T is then a Non Essential Variable.

In the post above js55 makes an excellent point that it is a good idea to perform RT prior to as well as after PWHT - unless you have utmost confidence in your welders or have a very,very low repair rate.
The client will be more than happy to pay for extra radiographs when he starts getting the money and scheduling costs associated with additional PWHT due to repairs,
Regards,
Shane

By Nanjing Date 12-02-2008 04:57

QW407.2 states that the procedure qualification test shall be subjected to PWHT of at least 80% of the aggregate time of production welds. This means that if your procedure was soaked for 60 minutes no production weld can have more than a total of75 minutes soak.
If it is not in the contract why not do your radiography prior to heat treatment B31.3 does not stipulate when it is done and I take it that you can only be welding P1 or P3 material.

By Shane Feder (****)

Date 12-02-2008 20:09

Hello Nanjing,
Long time no see.
Still toiling away in New Caledonia are you ?
B31.3 Section 341.3.1 (a) requires RT (or any examination) to be performed after PWHT for P numbers 3,4 and 5.
Have a great day,
Regards,
Shane

By Nanjing Date 12-02-2008 21:23

Shane, if his soak temperature is only 610 I would put my money on it that it is only P1 therefore radiography can be done just before PWHT. P4 & P5 are soaked at 700+.
So you are back in New Caledonia... proverbial bad penny eh!!!

By js55

Date 12-02-2008 21:49

QW407.2 is a Supplementary Essential Variable. So unless impacts are imposed a change does not require requalification.

By Nanjing Date 12-02-2008 23:42

So why else would qaqcmpm's client want a change to the heat treatment? Maybe the client does not know what he is doing either.