Reinforcement Pad for Long Weld Neck Flange

WRC 107 & 297 have big limitations when applied to reinforced nozzles.

What software are you using?

(.......... how long have you been designing pressure vessels?)

Dear Sir,

I used PV-elite software for design vessel. in common practice, no pad allowed for Long weld Neck Flange, but just to confirm with code.

Thank you.

I don't suppose you have an FEA nozzle program as well?

How did you determine failure according to 107? (297 does not apply to heads - only cylinder on cylinder)

What type of head do you have?

What parameters did you use?

As usual with ASME items Abdel gets my GA. In our 15 digester vessels we replace a 6" long weld-neck nozzle in the top hemispherical heads when it wears down about every 5 years. I do not reinstall forged long weld neck nozzles though, I instead replace them with 6", Sch.. 160 pipe with a regular 300 lb. weld neck flange. When I do this I save a good bit of money as well as get rid of what I consider an offbeat size(OD) nozzle. When I have new vessels constructed I am careful to require them to have the pipe nozzles instead of forged nozzles so that I do not have to keep forged replacement nozzles in stock. Due to the difference in strength rating between SA-105(forged nozzle) and SA 106 B (seamless pipe) my A.I. considers it an alteration so I have to do new vessel calculations. It always calls for us to use a 15" O.D.re-pad of 5/8" thick, SA 516 grade 70 material on the nozzle replacement.

pipewelder

Yes, that is a good answer by Abdel (a trivial one as it is)

However, what I was trying to establish was "Is there a problem in the first place" - the points mentioned above are appropriate and I was trying to determine if this just another case of someone mindlessly plunking information into a computer program without realizing the nature of it. Garbage in equals garbage out - and if the computer user does not realize the significance of the software applications ................

I think the OP is confused with "not allowed" and "not usually required".

Dear pipewelder and dear Guest, Thank you very much.

For pipewelder's statement "my AI considers it an alteration so I have to do new vessel calculations", I'd like to say that you are kindly requested to proceed such a calculations for those nozzles only, not a new (complete) vessel calculations, even he called that as an alteration.

Note. The calculations must include the effect of changing the nozzle material on the value of MDMT.

Yes Abdel, you are correct and a very good point, I may have misled when I said vessel calculations when I meant only calculations for the installation of the one nozzle of different material. The way I said it, some could have misunderstood what I was trying to say. It is confusing enough without me screwing up my explanation. You see I took a different approach to learning about ASME vessels and boilers; instead of going to college and learning the engineering I learned to weld and for the first 20 years I did the work and not the thinking behind the work. Now I try to do both and sometimes I may not explain things correctly.

For the record there is so little difference in the 2 materials that I tried vainly to argue to not treat it as a alteration but alas, my A.I. had the wisdom to see different. He then proceeded to pull section II-A from my book shelf to prove it as well. Arguing the point with an Authorized Inspector is probably a waste a time but by doing so I learn more.

Hi Abdel, "Guest" here again -

I would just like to say that I enjoy reading your well thought out answers with clear explanations, which are obviously backed by experience. I admire your patience to answer questions and take the time to properly explain (I cannot at times have the same patience).

I was just wondering if you have had a chance to read this thread yet:

http://cr4.globalspec.com/thread/29405/The-Best-Material-For

and was wondering your thoughts and/or opinions on the answers I provided. Was I too harsh? Should I have been more "civil"? Was I right in the choice not to provide an equation/answer?

(I almost think that that question may have been posted by a troll.)

I guess, finally - how about your same thoughts/opinions on this answer?:

http://cr4.globalspec.com/thread/29408/Minimum-Wall-Thickness

Hi guys, please help, what is a long weld neck flange? How is different from weld neck flange?

Thanx

Welded Neck Flanges, WN

Long Welded Neck Flanges, LWN

can u tell me nozzle dia?