Using eblow for Nozzle connection

[D2HANDLE]

Hello all,

I am working on a Pressure vessel designed to ASME Sec 8 Div. 1 Code with design pressure of 120 barg.
The Vessel dia. is 1050mm and it has an ellipoidal head at top.
Piping configuration requires that the projection of nozzle at the centre of top head be kept to a minimum, and Piping enginner asked me to consider a 90-elbow welded directly to the head (without any nozzle neck in between the head and elbow).
I am not sure if this configuration (i.e. using elbow for nozzle neck) is acceptable as per Code or not.It is also unclear as to how can we comply with Code opening reinforcement requirements.

Has anybody come across this before?
Kindly share your thoughts whether this is an acceptable solution?

Thanks for your kind advice ....

D2HANDLE

 

[europipe]

I think it's better to put a 50mm pup between elbow and tank,
Don't you need a reinforcement ring on the nozzle?

 

[europipe]

Can't you connect the nozzle under an angle of 10 degr. instead of 0 degrees on top?

 

[SnTMan]

D2HANDLE, not the best detail but it can be done. Use LR if you can to ease the welding.

As for reinforcement, you should restrict the limit of reinforcement along the nozzle wall (perp to the head) perhaps even setting it to zero, i.e. no contribution from the nozzle. This of course will require more contribution from the head.

I agree w/ europipe, use a pup if you can.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Mech2325]

Sntman: just for the purpose of knowledge. Can you tell me what is the significance of a pup as i haven't come across this term before. As per my knowledge it is a small type of a pipe spool. If it is this, then why cant we take a 50mm length of a nozzle neck and use it. Why is the term "pup" used??(just asking)

 

[SnTMan]

Mech2325, yeah, its just a short piece of pipe. Called a pup because, uh, that's what people call it. (Piece U Pipe, maybe?)

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Mech2325]

Sntman: U pipe?? What i understand is that this is a nozzle neck, say of sa 106 Gr. B, but just the term used for it is a "pup". However, dint get the u pipe thing. Can u explain?

 

[Jano6924]

D2handle, I agree on that using a pup would be the best option, but the elbow welded direct to the head is also acceptable. Now, since head nozzle projection is a concern, and if the head is elliptical or F&D, you may consider to use a head with no skirt, this is accepted by ASME VIII-1, and shall comply with UG-32(l).

Hope this helps.

 

[r6155]

Try with short radius and internal reinforcing pad, see UW-16.1 fig. (a-2). No pipe between elbow and head.

Regards
r6155

 

[racookpe1978]

Just a phrase: Pronounce the slang: "Hand me duh Piece Uh Pipe. I gotta cut me a pup piece to fit between here an' thare."

 

[SnTMan]

racookpe1978, thanks, I did leave out the aitch

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[europipe]

Maybe a nozzle horizontal on top? or under an angle of 10-15 deg. vert.and then an elbow?
D2 are you still there?

 

[racookpe1978]

Now, in the real world, an "elbow" will not fit through the perfectly drilled and perfectly perpendicular walls that define the "hole" of a theoretical pressure vessel wall.
You need a straight length of pipe to fit through the drilled/machined hole. Then this straight length of pipe is welded inside and out to the PV walls with a conventional fillet weld. With extra reinforcement, depending on the diameter and the pressures.

An elbow, however, DOES have a only a very short "near straight" tangent length that CAN fit through a drilled hole in a PV wall, but only if the PV wall is relatively thin. Get more than a 3/4 inch thick wall, and the elbow will no longer fit in the drilled hole. You need to scarf out the wall to get the elbow intrados to fit, and weld up (butter) the extrados to reduce the gap between elbow wall and PV wall.

BOTH the extra grinding and the weld buttering CAN be done, but either plan for the grinding and field fit "machining with a Metabo", or pretend it will work as-drawn and let your shop foreman do what he sees best.

 

[SnTMan]

Or, you can just set it on, if permitted.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[D2HANDLE]

Hello all...

Thanks a lot for the great posts and your valuable insights...

Don't you need a reinforcement ring on the nozzle? .

Well...to be frank , i am yet to check the reinforcement requirements..

I agree w/ europipe, use a pup if you can.

I also do agree..nozzle neck is a must between the elbow and head..and that is the way i have seen the nozzles all of my life..But the Piping guy says he is in a very tight spot and needs me to bail him out...

Try with short radius and internal reinforcing pad, see UW-16.1 fig. (a-2). No pipe between elbow and head.

Thanks a lot for your idea r61555, but the Client specification does not allow to apply internal reinforcement pad due to potential corrosion issues...

Maybe a nozzle horizontal on top? or under an angle of 10-15 deg. vert.and then an elbow?
D2 are you still there?

Thanks europipe..i think you've got a point ..will ask the Piper to consider this approcah..
I was out of the network...over the weekend..

you may consider to use a head with no skirt, this is accepted by ASME VIII-1, and shall comply with UG-32(l).

Thanks for the idea...but unfortunately again...the Client spec needs a minimum for 38mm for straight face on the head...there is no escape..

Get more than a 3/4 inch thick wall, and the elbow will no longer fit in the drilled hole.

Racookpe...you deserve a big thank you for the "real world" explanation..as an EPC engineer never thought of those...
Btw. the vessel head in question is just 20mm thick...

Thanks a lot to all members who took out the time and energy to read and post a reply ..really appreciate...

D2HANDLE