p#5B Base material using ER80SB-2 filler

Date 08-20-2003 13:36

I believe you are correct. I'm sure one of the "more senior metallurgists" will chime in shortly, but in the meantime here's my input.

Although you certainly may be able to qualify a WPS using the 80S-B2 (A number 3), it doesn't make the selection correct. As the client, you have every right to reject the filler metal and insist on having the contractor run a PQR with a more suitable filler metal. In your case a filler with an A number 4 is more appropriate.

ASME Section IX is pretty clear regarding filler metal F numbers: QW431 states - "The grouping does not imply that base metals or filler metals may be indiscriminately substituted for a metal which was used in the qualification test without a consideration of the compatability of the base and filler metals from the standpoint of metallurgical properties." It is obvious from this commentary that although the combination may pass (in a PQR), an evaluation of the appropriateness of the selection should be done. Although these comments are directed at F number selections, the comments also apply when considering A numbers.

Charles Hall

By Niekie3 (***)

Date 08-20-2003 18:31

Hi Insp

I have P5A material to be 2.25%Cr and 1%Mo material, not 5% Cr.

As the information that you have appears to be "hearsay", it is possible that the filler wire spec given to you was wrong. Maybe it is an ER90 filler. Then it would indeed be the correct filler.

If the filler is underalloyed (An ER80) then I would also be worried, because the creep resistance will be lower.

Hope this helps.

Regards
Niekie Jooste
Fabristruct Solutions

By MBlaha

Date 08-20-2003 19:02

While I am not and never ever claimed to be a metalurgist, I have welded boiler tubes that were T-22. I think if I am not mistake, these were 2.5 chrome moly. When welding these tubes, we used ER90 filler metal. These were tubes in the Platnen pendants. We were required to preheat to 300 degrees F. When welding T-11, which I believe were 1.25 to 1.5 chrome, we used ER80 for filler and were required to preheat to 150 degrees F. We also had to purge. Am I correct in this analysis?

Now that I have offered my negative 2 cents, I have a question. When you refer to creep temperature, do you mean the temperature at which the base metal reaches the plastic state?

Mike

By Niekie3 (***)

Date 08-20-2003 19:29

Hi Mike

I believe your T11 & T12 information is correct.

Regarding the creep resistance, I can explain it a follows:

At elevated temperatures the mobility of the atoms in the metal increases. This means that to reduce stresses within the material, atoms will want to start moving around. Typically then, atoms on the grain boundaries start moving from those boundaries that are in tension, and move towards those in compression. In so doing, voids are formed along the grain boundaries which eventually can lead to failure of the component. This is called "creep".

While this does lead to plastic deformation, it must not be confused with plastic "yielding" that can also take place at room temperature, or the loss of "short term" strength as the material temperature increases.

Some materials are better able to resist this migration of atoms than others. This makes them "more resistant to creep" than other materials. Typically a 2.25% Cr 1% Mo material will be more resistant to creep than a 1% Cr 0.5% Mo material, even though they could both be heat treated to give the same tensile strengths.

Hope this kind of answers your question.

Regards
Niekie Jooste
Fabristruct Solutions

By MBlaha

Date 08-21-2003 11:05

Niekie:

Sorry about mispelling your name. Fingers flying across the keyboard to fast :).
Yes, thank you, this does explain creep quite clealy. I was associating creep with plastic yielding.

Mike

By MBlaha

Date 08-20-2003 19:20

Ok, I pulled out ASME Sec. IV. T11 is a P# 4 group # 1 and is 1.25 Cr-0.5Mo-Si
T22 is a P#5A group # 1 and 2.25 Cr-1Mo. Man, I cannot believe this 49 year old mind (as of sunday) can remember back that far LOL. I agree with you Neike.

Back to work Mike LOL

By insp76

Date 08-21-2003 01:25

The P#5A was a typ-o on my part the mat. acually is a P#5B 5% CR. .5 MO. and today the issues were resolved with all parties present at a meeting , the engineers the operations rep.and a few of us inspectors. The materials engineer singed it off but with a note of caution never to use this filler mat. with that base metal again. They would have had to cut out 10 very hard to get to covection welds , reweld and the down time would have been very costly, so there taking a gamble I guess you could say. I voiced my opinions and concerns and the bottom line is that I am not liable for any failure of the equipment. The only thing that helps this situations is the fact that the welds were made on the 180 deg. turns on the ends of the box will be set in refract and will not be in direct contact with the heat coming from the radiant section below as the middle of the tubes will be. So I guess we`ll all pray and hope for the best. Thanks to all and have a good one.

By chall

Date 08-21-2003 13:05

P5B material when welded must be PWHT. I believe it is a requirement in all the ASME codes, unless the material is a non-pressure part welded to a pressure part (with another P#, which would not require PWHT).

Furthermore, P5B materials are utilized primarily because of their superior creep resistance. I'm sure you'll hear it again, but those welds should have been removed and redone using a more suitable filler metal and PWHT.

Charles

By insp76

Date 08-21-2003 14:41

Charles, thanks for your input, your correct about the pwht,and it`s being done this morning per asme b31.3 per table 331.1 ,it shall have a hardness test after completion of pwht per 331.1.7(a), it also shall be radiographed per 341.3.1 (a) after completion of pwht requirements are met....I 100% agree, the welds should have been cut out and rewelded properly with ER502 but my power is limited to only bringing a problem such as this one to the attention of all parties involved and give my recomendation for actions to be taken to fix the problem and in this case I clearly recomended cutting out the welds and rewelding them properly of couse....I really hope nothing bad happens such as a melt down of those 8 heaters that are all built side by side and or if someone is injured as a result of this mistake, but if it does, man oh man ,heads are going to roll !!!! ( but it won`t be mine). But still that won`t help the fact that if someone is injured I will have to live with that the rest of my life, just knowing I was involved. INSPECTION IS FUN ISNT IT!!! ....Thanks again.