new Pressure vessel, nozzle neck alteration 2

[msessi]

I have a an ASME VIII Divison 1 vessel which is now finished, tested and sitting at site.
However i want to cut a nozzle neck pipe of 2" in order to change the direction so a cut + 2 x 45° elbows may resolve the problem, but i'm not sure that such alteration need a new hydrotest or not, or this depend on cutting point on nozzle pipe neck??
Thxxx

 

[gr2vessels]

Shouldn't be a problem, since you are not performing a significant modification. Do you need to support this extended nozzle? If you have to weld on the shell, that is changing the story. Provided you can provide full NDE on the new weld to extend the neck, the extension will be a piping item, because the pressure vessel code will end at the new weld. Accordingly, you won't need a new hydrotest, since you are not changing any design conditions. You will need to check the details with your AI, because you haven't mentioned anything of the service requirements, code restrictions, etc.
Cheers,
gr2vessels

 

[msessi]

thank you gr2vessel for your quickly response, please find attached the discription of the problem, i think that we have to cut the nozzle neck pipe but the contractor ask if can avoid the hydrotest.the vessel are checked by VERITAS and no U stamp, and i prefer do not return to veritas and consult them so is that possible, is there any clause in NBIC or API 510 wich can be my proof to avoid re-test ?
best regards

 

[gr2vessels]

Since the vessel has not been operating, despite of completed hydrotest is still under the jurisdiction of new equipment, hence ASME VIII. There is no clause to prevent you cutting the nozzle neck and replace it with another neck, same material but different length. There is no pressure vessel calculations you have to produce to prove the safety of the modification. Accordingly, all you need is a fully documented work, including approved welding procedures, NDE after completion, material certificates, etc. Unfortunately, you can organize the engineering of this job, but you need an AI to overview the documentation and sign for conformity. I don't really know if there is a specific NBIC requirement for your job, but I believe all you need is record for the modification done in accordance with the original ASME VIII code.
Cheers,
gr2vessels

 

[Duwe6]

Cutting that nozzle at ANY time is going to require an AI and a Code Stamp. The cut will be inside the Code Boundary listed on the U-1 [and inside the manufacturer's hydro boundary]. ANY work inside that boundary requires a Code Stamp, other than work on a non-pressure component.

For your odd case, the requisite stamp can be either be the manufacturers "U" stamp [new vessel, never been in service], or another organization's "R" stamp. If it was mine, I would 'shop' for an "R" stamp operation with a 'reasonable' AI. I see this as a "Repair of a Routine Nature", meaning that Code-wise it is deemed to only require a memo in the vessel's file, not a full-blown "R-1" report with mandatory AI Hold-Point(s). Most AI's should, too [but not all - they have a lot of discretion on disallowing Routine Repairs]

It is your vessel, but the "U"-stamp on the Code Data Plate really means that "U don't mess with it". All stamp-holding Code Shops have had to prove that they understand all the rules and possible pitfalls of pressure vessels. If you, or sombody you hire, does not have the appropriate Code Stamp, it is not legal to perform the work. Sorry.

 

[gr2vessels]

Sorry..which U stamp??

 

[Alex2012]

gr2vessels is correct. This is not a coded stamp vessel to begin with.

 

[mastertiger]

As far as I know. API 510 states that:
The following should not be considered alterations:
any comparable or duplicate replacement,
the addition of any reinforced nozzle less than or equal to the size of existing reinforced nozzles,
and the addition of nozzles not requiring reinforcement.

You didn't say if the equipment was placed in service or not. If it was, API 510 gouverns otherwhise two solutions could be followed:
-If it's an alteration a new design data had to support the changes made
-If it's not an alteration run the vessel for a period of time (API 510 will gouvern then) and after that make the change you want.

As far as I know also and correct me if I'm wrong piping components are not considered parts of a pressure vessel. It is wise to consult with a pressure vessel engineering for more details.

Best Regards

 

[msessi]

thank you for your replies
the plant is under construction
mastertiger i think that nozzle pipe neck is included on pressure vessel boundary, concerning API 510 i didn't found any of this type of intervention.

Best regards

 

[GenB]

Complicated. Since no stamp you need not answer to the national board. What about your customer? How you will know it the new nozzle will be without discontinuities? If you are able to do the NDE that may get you off the hook. Will the customer's q.c. person approves it? All that is a consideration.

 

[Duwe6]

Sorry; "ASME Sect VIII, Div-1" implies a "U" stamp; "in the manner of Sect VIII" means w/o stamp to me.

If this vessel is not stamped, shorten the neck using a welding procedure and welder(s) certified to ASME Sect IX. If the existing welds on this nozzle were X-rayed [almost certainly they were not, then you are required to X-ray the finished weld. In other words, you need to duplicate what was done when the vessel was originaly fabricated. Add the records of your change(s) to the vessel documentation 'package'.

If it were my vessel, I would use the services of a certified API-510 Inspector to oversee this work and have him/her decide about what testing [if any] will be required on the new weld. This Inspector will take care of generating the appropriate documentation of this change to your vessel.

 

[gr2vessels]

Just out of curiosity, is the 'certified API 510 inspector' vested with supra-natural powers and secret codes which are not available to the ordinary engineers and gives them right to decide over and above the 'ordinary' engineers who are obeying the code? Are there other tests that are not normally allowed/required by the ASME VIII and are only accessible to 'API 510 inspectors'?? Are you people all right?? Why can't you just follow the code without an 'API 510 inspector' telling you to follow the code?? Do you need an inspector to write for you the appropriate documentation? Sorry for asking these questions, but I make my own decisions based on the code without the need of an 'inspector' telling me how to follow the code.

 

[Duwe6]

Anyone who has passed the certification requirements for API-510 has the requisite knowledge. Thus you 'get your money's worth' even if you don't know enough to personaly determine if the Inspector is knowlegable. Present company excepted, but more Mech Eng's than not are not sufficiently knowlegable of the details required to fufill ALL the requirements of specifying, overseeing, testing, and documenting an ASME vessel modification.

The only other way to be certain that a purported expert is actually as good as he/she claims is to ask if they hold a National Board certification. Otherwise, you can make your 'best guess' if "the 'ordinary' engineers who are obeying the code?". Just because an engineer wants to get it right doesn't make that person capable of getting it right.

I don't recommend hiring non-degreed engineers to do engineering design work, nor do I use 'just another engineer' to do Code inspections, evaluations, or documentation.

 

[gr2vessels]

I understand where you're coming from;- I just tend to disagree that the world wide engineers cannot be good because they don't hold an NB certification. They do and many of them don't even speak English to prove how good they are. And they are good, not 'just another engineer'. Their work speaks for them, in absence of the certification. BTW, please remind me which country is selling over the internet engineering degrees. If you have money, you get a degree to do engineering work...