Parallel Tangential nozzles through the knuckle

[bayardwv]

I'm looking for help with finding the proper way to calculate reinforcement for (2) 12" tangential nozzles that are going thru the knuckle of a 48" Ellip Head, into the shell & thru the head to shell seam, and are parallel to each other. One of the nozzles is set on and the other will project inside and attach to internal piping.

I need help explaining why this isn't recommended, using technical terms, vs. me saying "Trust me this isn't a good idea, I can't even got the PV Elite software to accept this configuration".

 

[TGS4]

Not to say that this couldn't be done, but for a Div 1 vessel, this would definitely fall under U-2(g). And, if it were me, I would absolutely need to know whether that head is an actual 2:1 semi-ellipsoidal or an "equivalent" 90-17 torispherical head.

You're going to need FEA to design that.

 

[Soave]

As TGS4 replied, you need FEA. Since the WRC 107/297 does not find the actual stress values for your case.

 

[r6155]

Hemispherical head may be better.

Regards
r6155

 

[inammanj123]

we can do it in the in build FEA module on COMPRESS software??

 

[Soave]

inammanj123

I guess not, since we can not model a tangentinal nozzle attached to head.
(I just tried to model, but I didn't get it)

 

[TGS4]

No. You will need to get a specialist involved. When you do - please make sure to note to them whether you have a true 2:1 semi-ellipsoidal or a 90-17 "equivalent" torispherical head.

 

[bayardwv]

Thank you for replies. After further review the customer has agreed to another nozzle layout that suits their needs for less cost.

 

[tigny]

Dear TGS4,

Is there a reason for requesting to keep the design being on a 2:1 ellipsoidal or 90-17 "equivalent"?
What if you give all the geometric details of the head to the specialist?

In the particular case where the head would not meet a standard for heads, wouldn't it be expected that the only solution for verifying the design would be to go to U-2(g); therefore, for example, using Design By Analysis of ASME.BPVC.VIII.2 §5 method (making sure Protection against plastic collapse, Protection against collapse from Buckling ... are checked)?

best regards,

tigny

 

[TGS4]

Most heads are elliptical, so I just assumed. Even though most people (and the Code currently) consider them to be equivalent, they are most certainly not. What shape is your head?

Definitely you will need to give all of the information to the specialist, including the fabrication tolerances. This type of analysis requires a top-level expert, as these things can get complicated quickly, and the less-skilled specialists will miss those complications.

 

[tigny]

What shape is your head?

We have shapes that we include in order to keep compact casings for machines (compressors, turbines).

We try to make use of ellipsoidal shapes; sometimes we have flat heads. Because of compact shapes, we cannot always keep the openings clear of the heads nor the body flange.

For the compactness of the casing we sometimes have interference of nozzles on the heads, for which we make FEA analysis using the rules of ASME.VIII.2 §5.

For an indication on the shapes of our casing, please have a look at similar designs in german code KTA page 136, illustrations A 3.2-1 and A 3.2-2. (we don't work with this code, it is just a exemple of casing shapes).

tigny