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Up Topic American Welding Society Services / Certifications / Pressure Vessel - Fabrication Tolerance
- - By J.82Nathan (*) Date 09-19-2013 08:02
Dear All,

I am now preparing necessary document for U-Stamp Certification Project. While doing it, I have got a problem about fabrication tolerance for my Pressure Vessel that are not specified in the ASME VIII book. For example the tolerance for nozzle orientation, for nozzle hight, etc..

Could anybody please help me if you have experience about it?

Thank you very much and looking forward to your support!
Parent - - By qcrobert (***) Date 09-20-2013 15:14
More info please.  What necessary documents?  Are you applying for U stamp certification or preparing to fabricate a pv?
Parent - - By J.82Nathan (*) Date 09-23-2013 02:10
Dear Sir,

We are preparing for U-Stamp Application. While doing this we have to prepare Manufacturer Fabrication Standard which mentions fabrication tolerances. For example, we have to make a document for Nozzle Orientation Tolerance, Nozzle High Tolerance, etc.

Thank you very much for your attention and hope you can help me to solve this issue.
Parent - - By G.S.Crisi (****) Date 09-24-2013 00:05
I've sent you a personal message.
Giovanni S. Crisi
Sao Paulo - Brazil
Parent - By J.82Nathan (*) Date 09-25-2013 03:25
Thank you very much for your support Mr Giovani S. Crisi. I have left my email address in your Messages.
Parent - - By 46.00 (****) Date 09-25-2013 03:36
Is this a secret answer or can you share with the rest of the forum?
Parent - By G.S.Crisi (****) Date 09-25-2013 20:36
No, this isn't a secret answer and I'll share it with all of the other frequentors of this Forum.
A few days ago, Nathan sent me a Private Message asking me whether I had some kind of document stating the fabrication tolerances of pressure vessels. As the question came via a Private Message, I thought I should also answer via Private Message, and that's what I did.
But, as Fortysix believes I should share the information with the rest of the Forum, I'll do that.

Very few fabrication tolerances are stated on ASME VIII Code. The rest (and they're quite a few) are stated, as Joey clearly said, on Engineering Standards issued by engineering companies or corporations that are users of pressure vessels (Esso, Dupont, Monsanto, Dow Chemical etc. etc.). I've got with me, since my days of erector engineer, the fabrication tolerances issued by an engineering company called The Power Gas Corporation, from London, England. This company doesn't exist any more, so if I show their standard to someone else, I'm not infringing any patent nor am I revealing any confidential information that belongs to a company that doesn't exist.

So, I scanned the standard (it was originally a printed copy) and sent it to Nathan. If someone else wishes to receive it, please ask, mentioning his (her) webmail address. This is what Joey suggested, isn't it?

Giovanni S. Crisi
Parent - By Joey (***) Date 09-24-2013 03:25
The most easiest way to solve your problem is to copy from other vendor's procedures.
Parent - By CWI7611 (**) Date 10-26-2013 00:32
I know this is late and may be of no use to you but you might start by contacting the Pipe Fabrication Institute. They have some tolerances for dimensioning vessels with nozzles and such. You could start from there. They wont tell where you put nozzles and orientation, that will come from design, but they do have some information about tolerances for designated locations, off plane for flange faces and other information. Of course you have to buy their Standards but they cover many other subjects as well as piping tolerances. I realize this is not for pressure vessels but it is a start.

Good Luck!!!
- - By J.82Nathan (*) Date 09-26-2013 01:01
Dear All,

Please be informed that I have received an email from Mr Giovanni with a sheet of Tolerances for Pressure Vessel Fabrication. I would like to say thank you all for your help, support & share, especially I would like to send my special thank to Mr Giovanni for his very kind support.

Thank you all very much, my problem is solved.
Parent - - By Hnazzim Date 09-01-2015 23:40
Dear Nathan,

I'd like to request for a copy of the sheets for Tolerences for Pressure Vessel Fabrication, if you still have it.


Parent - - By welderbrent (*****) Date 09-02-2015 00:56


You have queried a post that is 2 years old.  Prof. Crisi has passed away and Nathan is not real regular here.  There are others who may be able to assist you but will probably need more info as to the specifics of your need. 

This is not my area of expertise in any way, shape, or form so I'll stand by and wait to see what transpires.  Just be patient and you will get some answers.

He Is In Control, Have a Great Day,  Brent
Parent - By 46.00 (****) Date 09-02-2015 19:23
Hi! I'm going to post a link to a NIST site that provides a document that you could use as a tool to make a 'check list' of things or questions to ask for a contracts requirerments. This document is specific to certain products so most likely will not meet your every need. There is no magical list that covers every code or condition or client specs. Even the Prof. Crisi's list was out of date. This document is by no means conclusive, but it does provide what I believe could be a starting point to your needs given the very little information provided, and it's free!
Up Topic American Welding Society Services / Certifications / Pressure Vessel - Fabrication Tolerance

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