Section 8 Div 1 Vessel - Welding Inspection Question 8

[tc7]

I have a large accumulator (600 psi operating pressure, saturated steam service) that presently has a nozzle with attaching pipe. The pipe (A106) is capped approximately 25' downstream. I want to cut the pipe 12-inches from the nozzle and re-cap the pipe. There will be no valves between the vessel and the new cap. Which Code shall apply? Vessel code Section 8? or power piping code, B31.1?

I believe my Section IX qualified WPS's for A106 pipe is applicable in either case.

At issue is the type of inspections required. I think Section 8 may require radiographic exam but B31.1 will not.

Thanks

 

[unclesyd]

If by your description this is the first weld on the vessel nozzle so the weld belongs to the vessel.

 

[metengr]

You need to determine if the nozze is welded to the attaching pipe as you describe. If the nozzle on the vessel is indeed butt welded to the pipe, the pipe beyond this butt weld falls under B31.1 for design, fabrication and installation of the cap.

 

[CodeRef]

ASME Section VIII-1, paragraph U-1(e) (1) addresses vessel boundaries where connections are made to piping and the vessel scope (by design) is indicated on the Manufacturer’s Data Report. Typically, when a vessel is connected to a piping component, the Manufacturer will have to determine where the scope of the vessel ends. The Manufacturer will then define the scope by completing the Manufacturer’s Data Report (MDR) so that others will know where the vessel scope ends. On the MDR, for nozzle boundaries, look for the items listed under the description Nozzles. If, for the nozzle in question, there is a flanged connection and the flange specification is listed along with the nozzle piping spec on the Data Report, then it was designed with a flange and the scope will end at the face of the flange. If only a piping specification is given for the nozzle (A106) then it would be safe to assume that the vessel scope ends at the first circumferential joint attached to a piping component.
From what I gather, you are removing a piping component from the vessel. How would this affect the operation of the vessel as designed? Perhaps discussing with the Jurisdictional Inspector is a good idea. It may not hurt to discuss this with them as they may need some assurance that the design has not changed. Could it have been that this nozzle was considered as an inspection opening? These are only a few questions I can think of right now.

I recommend reading the explanation on page 1 from the following newsletter published by HSB in November 2000:

http://hsbct.com/uploadedFiles/CTWeb/AllImages/PP-2001-11.pdf

 

[tc7]

Thankyou for the insight.

We are doing some housekeeping here and want to eliminate the 25 foot run of pipe since it is now out of service. So I thought it best to make modifications to the pipe with a new flange and blank instead of at the nozzle.

My circumstance is analagous to the nozzle on the right side of the diagram in 2007 Section VIII Div 1 Figure UW-3: weld D and weld B exist where weld B is the attachment of the existing pipe to the nozzle; I will be cutting beyond existing weld B and adding new weld C which will be a new flange to attach a blind. Based on this diagram and all advice rec'd I believe I am definitely required to apply the Section VIII inspection criteria.

My new Category C weld will be for >10NPS but wall thickness is less than 1.125, therfore by UW-11(a)(2) I require no radiography. Does this meet with your agreement?

 

[CodeRef]

Well, as I said, I would need more info to make a clear definitive answer for this particular vessel. If within the scope of VIII-1, then it will be within scope of NBIC (where applicable)as a Repair/Alteration and thus, involvement of the Jurisdictional/Authorized Inspector who will determine final acceptance.
You seem to be quite capable of interpreting the requirements.
Good Luck!

 

[Ballbearing1]

tc7,
Just reading through some old postings, sorry if my advice is too late.
To be able to have an exemption from RT (UW-11(2)(a)) nozzles must be 10NPS or less and also 1.125" WT or less. You have stated your nozzle is greater than 10NPS ??
However, the joint C you mentioned is the second circumferential weld from the shell so ASME VIII is not applicable.
ASME VIII is only applicable to the first circumferential weld.
The explanation posted by Codejackal states "Note: the nozzle attachment weld to the shell or head (D) is not considered the first circumferential weld" (this would be (B))and you intend to have another weld (C)which is outside the scope of ASME VIII.
If it is B31.1 then the temperature will govern RT or not. (Your pressure is OK as per Table 136.4)
Over 750 degrees F design temperature will require RT.
Hope that helps,
Regards,
Shane

 

[CodeRef]

Ballbearing1, Knowing that the repair would involve an AI, I left the obvious questions unanswered. However, with your recent post, I think some clarification is needed.

To be able to have an exemption from RT (UW-11(2)(a)) nozzles must be 10NPS or less and also 1.125" WT or less

Incorrect, the "and" that you have put into the statement should be a "nor" So, if you have either condition satisfied, RT is required.
Here are the actual words from UW-11(a)(2).....

........Categories B and C butt welds in nozzles and communicating chambers that neither exceed NPS 10 (DN 250) nor 11?8 in. (29 mm) wall thickness do not require any radiographic examination;.............

Please reference Interpretation: VIII-1-07-14 which clarifies UW-11(a)(2). Found Here:

http://cstools.asme.org/csconnect/pdf/CommitteeFiles/864.doc

Also,

.....the joint C you mentioned is the second circumferential weld from the shell so ASME VIII is not applicable

Not in every case, You must review the Manufacturer's Data Report (MDR) to verify that statement is correct. For example, If I had a bolted cover w/blind flange used as manway on a vessel and the manway nozzle contained a circumferential joint, I could not exclude the bolted cover from the vessel scope. For consistency, this rule applies for any nozzle and not just manway openings. When a pressure vessel is “U” stamped, the pressure parts covered by the stamping are all the parts required to hold pressure and identified on the MDR.

 

[gr2vessels]

My two cents;- since U-1(e)3 is not applicable in this case, then U-1(e)1 applies. The capping butt weld is the first weld after the nozzle/shell joint, hence the weld and cap are part of ASME VIII, not piping code. After all, the nozzle neck left on the vessel is only a 12" stub, having a capped closure. I can't see what's the commotion...
Cheers,
gr2vessels

 

[Ballbearing1]

Codejackal,
I am not sure what your point is. I purposely did not quote verbatim from the code as I was trying to make it easier for tc7 to understand.

"My new Category C weld will be for >10NPS but wall thickness is less than 1.125, therfore by UW-11(a)(2) I require no radiography. Does this meet with your agreement?"

tc7 stated that he had satisfied 1 of the 2 requirements for exemption from RT and therefore he believed he did not have to perform RT, my response was it had to be less than 10NPS and less than 1.125" in order for the exemption to be applicable.

gr2vessels,
"My circumstance is analagous to the nozzle on the right side of the diagram in 2007 Section VIII Div 1 Figure UW-3: weld D and weld B exist where weld B is the attachment of the existing pipe to the nozzle; I will be cutting beyond existing weld B and adding new weld C which will be a new flange to attach a blind. Based on this diagram and all advice rec'd I believe I am definitely required to apply the Section VIII inspection criteria."

Based on tc7s explanation above weld D is the shell to nozzle weld and weld B is the nozzle to pipe weld.If he was cutting at weld B and welding a flange on that would be fine as weld B is the first circumferential welding joint connection.However, tc7 clearly states that he is cutting past weld B and adding weld C which in my opinion makes it the second circumferential weld joint and therefore outside of ASME VIII scope.

Please advise if I am misinterpreting the intent of the code,
Regards,
BB

 

[CodeRef]

BB, You are correct and I was wrong regarding the RT exemption. I will admit my mistake. Less than 10"NPS and 1.125" does not require RT.
Kudos to you for correcting me.
Regarding the vessel scope, I agree w/gr2vessels statement.

 

[Ballbearing1]

Codejackal,
Thank you for your response.
However, I am still confused over the code jurisdictional boundaries.
If the code and the code explanation you supplied both state the first circumferential welding joint connection (and I am not including the shell to nozzle as a Circ weld)then if we have two circumferential welds surely the second weld falls outside the vessel boundary ?
Regards,
BB

 

[vesselfab]

well, if it were here to get modified

I would do it as an alteration to add the flange and the blind which now is permanent part, like a manway blind

why wouldn't you want to radiograph a 600 psig weld that is welded overhead, out of position, and in outdoor conditions where you can porosity out the ying yang

i don't know your pwht situation,,,but if pwht for service condition, you will have to again. If it was pwht for code thickness you will not have to pwht because you're new weld will be thinner.

 

[CodeRef]

BB,
The following was taken from HSB Pressure Points Newsletter printed in November 2001. To read the entire article, click the following:

http://www.hsbct.com/uploadedFiles/CTWeb/AllImages/PP-2001-11.pdf

The case above is not exactly describing the situation here, and I can understand your differing opinion because the issue is concerning the welded joint intended for a piping connection.
Also note that this is "after construction and stamping".
gr2vessels states how U-1(e)(3) cannot apply since U-1(e)(3) discusses pressure retaining covers for vessel openings and I agree with that. A Manufacturer would only put a nozzle on a vessel if it was intended as an opening or a connection to a piping component. Because we are dealing with a case that is after construction, and because it would be imprudent to remove the nozzle altogether and install a flush patch, the wisest choice of action would be to cap the nozzle, or place a blind flange w/cover at the end of the nozzle. In my opinion, exempting the cap or blind flange from the vessel scope would not be keeping with the intent of the Code.

Perhaps an inquiry should be made of the NBIC as to how to handle this situation because I have not yet found any interpretations in the NBIC that address this.

 

[Ballbearing1]

Codejackal,
For some reason we seem to be going around in circles.
Both yourself and gr2vessels seem to believe that tc7 is going to cap off a nozzle with a flange and blind flange.
If that was the case I would be in total agreement with you.
However, the way I read it he is leaving a small piece of pipe welded onto the nozzle therefore he has shell to nozzle weld, nozzle to pipe weld (first circumferential weld)and then pipe to flange weld (second circumferential weld)
Again,as you have stated, capping the nozzle without leaving any pipe on would be the most practical thing to do,
Regards,
BB

 

[tc7]

This has been fascinating for me to see the exchange of ideas. True that I am leaving a short stub to the nozzle and flanging or capping at the end of this existing stub. The original vessel was tested and delivered with this stub in place (and capped). We subsequntly cut off the cap and added valving and pipe run to that stub. I am now removing said valving and piping from that stub. The stub remains.

My new weld will be the first circumferential weld AFTER the original and still untouched nozzle-to-existing stub weld.

Based on all of the above discussion, I still vote that the new weld is inherited by the Section VIII vessel.

 

[vesselfab]

basically

if it is flanged and blinded it's code

if you take off with pipe across plant....its pipe

 

[CodeRef]

BB,
Are you saying that a welded closure (such as a pipe cap) placed on a vessel nozzle, not intended for a piping connection, is not within the scope of the vessel boundary only when it is beyond the first circumferential weld?

 

[Ballbearing1]

Codejackal,
Irrespective of whether it is a cap or a flange, it still must comply with the code.
Is the weld in question the first or second circumferential weld (not including the shell to nozzle weld) ?
If tc7 welded his flange directly onto the nozzle there would be absolutely no problem, but for some reason he wants to leave a bit of pipe in there.
Lets just agree to disagree, I think we are just going around in circles.
Regards,
BB