Nozzle damaged in a truck accident.

[SANJCALG]

A pressure vessel fell from a truck. The vessel has a skirt. The vessel has 8” liquid outlet welded to the bottom head with a 90 degree elbow and is projected outside of skirt as per standard design. This liquid outlet nozzle has got twisted in the accident and the face of the flange is no more perpendicular to the radius of the skirt. There is a possibility of cold bending of the nozzle pipe / elbow. API 579 does not exactly address this situation. There is no ovality issue which is address by API 579.
It is evident that the nozzle elbow or pipe or both have undergone some cold work and hence there is a possibility of residual stress. Is there any code or standard that addresses this issue and provide any guide line?

 

[unclesyd]

What is are the physical parameters for the nozzle along with the MOC?

 

[metengr]

Is this a new vessel (never in service) that was fabricated and shipped to the site for installation or is this an in-service vessel that was shipped to a repair shop or for installation at another facility?

 

[eyec]

send it back to the shop and have them repair it to your original purchase/repair order specifications.

if the nozzle was not included in your original PO then you need to find out the guiding specification/code governing the nozzle - as pointed out above.

regardless if it is new or a repair go back on the trucking company for the cost of repairs.

this following short description might lead you to review other codes that may aide in answering your question.

http://catalog.asme.org/Codes/PrintBook/FFS1_2007_FitnessforService.cfm

Steven C
Senior Member
ThirdPartyInspections.com

 

[SANJCALG]

Nozzle pipe material is SA 335 Gr. P1. Vessel is new and being transported to site. It is impractical to send the vessel back to shop. Any repair has to be done at site. API 579 is not of much help as there is no dent or change in ovality or flattening of the elbow. The nozzle being flexible has been bent by the impact. Vessel has received PWHT.

 

[metengr]

The repair code that is most applicable for this would be the National Board Inspection Code (NBIC), if any weld repair is required to either replace the flange or perform a weld build-up with subsequent re-machining. I am not too worried about the local deformation in the pipe or flange considering the material of construction. I would request surface NDT of the affected regions, as a minimum.

You need to involve your Boiler Machinery insurance carrier every step of the way to assure adequate scope of repair and to help you recover the cost of repairs to this vessel.

 

[gr2vessels]

By the way, the flange affected is a piping item, since the first circular welding of the 'nozzle', after the nozzle to shell/head weld, is the weld to the elbow, hence the elbow and the rest of pipe and flange protruding through the skirt are piping items and subject to the plant piping specification, not the pressure vessel code.
Cheers,
gr2vessels

 

[jte]

gr2vessels-

Yep, as long as the vessel documentation makes that clear. In fact, I often recommend setting a VIII / B31.3 "spec break" on the drawing and making a clear note on the U-1 to the effect of "Some B31.3 piping was included in the vessel fabricator's scope of work and welded to the vessel in the vessel shop." In this case, I presume the nozzle consists of a vertical pipe with an elbow and a horizontal pipe with a flange. As you point out, the vertical pipe to elbow seam could be made the spec break. This could save a lot of effort in this case since the repair could be dealt with as "piping" and not "vessel".

However, U-2 allows the inclusion of other components which meet VIII-1 as within the scope of the vessel, and in most cases this leads to the face of the flange being made the end of the vessel scope. Once in VIII domain, it is difficult to get out: It would be an alteration.

If Sanjaycalg's vessel drawing shows the elbow, horiz pipe, and flange with no clear indication of a spec break, and the notes indicate that the drawing is referring to a Section VIII-1 vessel, then the implication is that the scope was extended to the face of flange. Another item to look for is the Manufacturer's Data Report: If the nozzles are listed with some notation of flanges such as 6" Cl-300 RFWN then clearly the flanges were incorporated into Section VIII territory.

It all boils down to what the designer/fabricator/user specified in the original doc's. Any changes subsequent to that get into the world of alterations...

jt

 

[racookpe1978]

OK. Concur with your ID of this bent nozzle being considered a "pipe" (for repair) vice a "pressure vessel" .

But, physically, doesn't he have to convince the insurer and owner that that "first weld" of vessel wall-to-pipe is not cracked, that the tank wall is not deformed, AND the pipe-to-elbow-to-pipe-to-nozzle welds are still good?

Sudden cold bending like this on a new tank should NOT be a re-bend-it-to-fit-the-drawing solution, but - if that first weld is physically good (PT and inside AND outside to look for cracks), then the bent pipe and bent elbow(s) should be cut off and the nozzle stub replaced with good (straight) pipe, new (replacement) elbow, etc.

The original nozzle is almost certainly good, and can be cut off, re-weld prepped, and re-used to the new pipe.

 

[SANJCALG]

Thank you very much for your efforts and time. Your responses made it easy to finalise a way forward.

 

[roca]

I agree with jte
The only time I've seen a "spec break" on a vessel is when the flange is inside the skirt - which is normally a no-no due to leaks inside the skirt.
If the elbow+pipe+flange are welded together to the vessel then its part of the vessel.
Would you say that a flange on a shell nozzle is a piping component?
I don't ever seeing a spec break clearly shown on a nozzle on a vessel fabrication drawing like the one in question.

 

[vesselfab]

I have seen it, but it's somewhat rare.

Demethanizers that have long pipe runs down the vessel are spec'ed out as pipe past the first weld.

for a tail nozzle, unless it was specified originally, and listed that way on drawings and calcs....the spec break is at the flange, just like a normal nozzle.

well, that's the way we do it, anyway.