Does welding a nipple on a MW BF constitute an alteration? 1

[KernOily]

Guys I am looking for opinions here. I am not a Sec VIII expert by any stretch, so maybe you can best answer my question by pointing me to the appropriate Code section.

A client of mine wants to add a new line to an existing vertical vessel by welding a 3" sch 80 316L nipple to a 24" manway cover, i.e. the MW blind flange. This is a shell manway. This will be a normal process line. They are proposing this to keep from having to add a new shell nozzle and thus be required to undergo a formal vessel alteration.

The blind flange on the manway in question is just a regular ANSI B16.5 forged blind flange in 304L/316L. This vessel operates at low pressure (2 psig), ambient temperature, in non-lethal service. Would this constitute a formal alteration?

Thanks in advance for your help. Thanks!
Pete

 

Hi Pete,

Short answer this time I promise. The shortest possible answer is "it depends upon your juridiction". But that is not what you are looking for.

The ASME B&PV Code only covers new construction. You have to go the National Board Inspection Code, ANSI/NB-23, for your answer.

In Appendix 4 of the NIC there is a definition of "alteration". Alteration - any change in the item described on the original Manufacturer's Data Report which affects the pressure containing capability of the pressure retaining item. Non-physical changes such as an increase in the MAWP or design temperature of a pressure retaining item shall be considered an alteration. A reduction in minimum temperature such that mechanical tests are required shall also be considered an alteration.

Most people read this to say that if you put a welding electrode on any part of the pressure boundary (after the "U" stamp has been applied), you have made a repair or alteration. This means (depending upon the jurisdiction)it has to be stamped with an "R" stamp.

Before you make the alteration you have to obtain an Authorized Inspector's authorization to perform the alteration. The AI will not be kind if you call upon him to bless-off something that you did without benefit of clergy. Part RC-2000, the AI must determine that the alteration methods are acceptable before the alteration is made. The alteration must me made by an "R" stamp holder.

But you gotta read the NBIC to get the whole picture.

Best regards, John.

In NB-23, Part RC (Repairs and Alterations)

 

[prex]

Your modification is for sure an alteration, as the cover is part of the pressure vessel.
Of course it's clear that this won't be a problem for the vessel, with a so low design pressure, but this doesn't relieve you from taking the correct steps according to the code and procedures applicable.
On the other hand, as this vessel is not within the scope of ASME VIII because of the low pressure, it will depend on the local regulations whether you will require a formal inspection approval or nothing at all. prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

Your addition of the 3 in NPS nipple will be a repair if the thickness of the shell (MW cover in this case) is equall or less to 3/8". Otherwise it's an alteration. NBIC Code Appendix 6 B 10.

 

[rustbuster1]

The ASME code only applies to units operating above 15 psi. The NBIC is based on the ASME Code and therefore also will not be relevant here. I think you are making a mountain out of a molehill - if you added a 3-in. nozzle to a tank wall would it be an alteration? I believe you will find NOT, especially if there are other 2 or 3-in nozzles on the tank and you use the same nozzle mounting arrangement.

I'm interested to learn why U's and R's apply here at all from those wiser than me...

 

[KernOily]

Guys thanks for your replies. I should have mentioned that this vessel is a U-stamped vessel with 50 psig MAWP. I forgot to state that in my initial post - my apologies.

Thanks very much for your input. Thanks!
Pete

 

[KernOily]

One other item - this change will be made on an in-service vessel under plant shutdown/turnaround conditions, so the molehill-mountain analogy doesn't hold here. Waiting on an AI for an inspection while mega $$ goes down the drain at 3 am in the morning doesn't make anybody too happy... Thanks!
Pete

 

[twjag]

Re plant shutdown/turnaround conditions:
To reduce time, you can prepare ASME calcs & paperwork, NBIC Form, install nozzle in new blind flange, & hydrotest new blind w/nozzle (if required by AI or Jurisdiction) prior to shutdown. At shutdown, remove existing blind & install new blind, have AI inspect installation, install alteration name plate, & return vessel to service.

 

[mbag]

I'll put in my two cents. If the Item is a ASME Section VIII, Div. 1 pressure vessel, the Manway blind is on the Data Report and calculations are required, this is an alteration. In some cases the jurisdiction and/or the AI may tell that it still is an alteration if the blind is not on the Data Report (the manway being an integral part of the vessel).
The point that is being missed that even the NBIC refers you to the original Code of Construction. Your are building a new Part(ASME) if your nozzle is a pipe welded to a flange connection or fitting using new materials. It is not a new part if the nozzle is a pipe which the Code stops at the first butt weld. The alteration weld would be the nozzle to blind.

 

[ExAI]

Gentlemen,
I directy your attention to NBIC appendix 6 parts B9 and B10. This might NOT be an Alteration. Your reason for installing it in the manway vs. the vessel shell may be incorrect. Also, I caution you about installing a nozzle in a manway access. The production piping attached to this nozzle will interfere with the purpose of the manway and may cause improper maint in the future.

 

[StressGuy]

Well that issue can be addressed easily enough by adding breakout flanges at some short distance away from the manway connection to allow the removal of a spool with the manway cover to provide room to enter the vessel. I wouldn't be too concerned about that one. Edward L. Klein
Pipe Stress Engineer
Houston, Texas

All opinions expressed here are my own and not my company's.

 

[ExAI]

I agree that a break out connection will work just fine in allowing access however, you must consider that Jurisdictional Inspector's, Insurance inspector's, and other's may consider this modification to be the removal of a dedicated manway by changing it to a process nozzle. The requirements of UG-46 clearly allow this type of access opening but you might not want to play that game with the inspectors, especially if a nozzle addition in another location is more cost effective which was the premise of my comment. to disguss this further, Email me at
LaneBQS@att.net

 

[rdf]

I know it's a little late to jump in on this thread, but here goes:

The Code Jurisdiction stops at the first gasket face, if the original national board forms did not include the cover in the report then no break-out spool section would be required.

Still you can't proceed without a blessing