Outlet arrangement with B16.9 Cross in COMPRESS

[aard]

Hello,

I have a vessel with an outlet arrangement attached to the bottom head in which 3 nozzles (NPS 3 each) are connected with an B16.9 Cross (See the sketch attached). I have 2 ideas to model the cross in compress.

The option A is to attach a pipe no the main nozzle necks but compress will study this as an opening and i will need a pad wich is goig to be diffucult to add because i will no have too much area for it.

The option B is to model the 3 nozzles separately as you can see in the sketch.

Please let me know which pros and cons you see in these options and if you can recommend me another more accurate.

Regards

 

[SnTMan]

aard, I suppose it depends on what you need to achieve with your model. If you want the most accurate visual representation and parts count I'd go with your Option A and disregard the reinforcement calculations, since you presumably know they are not applicable.

Keep in mind I am not a Compress user.

Regards

Mike

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

 

[aard]

Thanks,

The visual representation is not important, my concern is the more accurate calculations.
I would discard the option A for calculations.

In a nozzle design you need to check the following:
1.- Required Head/shell thicknes UG-37(a)
2.- Nozzle required thickness calculations.
3.- UG45 thickness calculations.
4.- Check the openings and reinforcement.

If I model each model separately, do you think that I would be calculating properly the 3 nozzle? The consideration 4 in the last consideration ins not necessary for nozzles N2 and N3

Other option that comes to my mind is to only calculate N1 and obviate the N2 and N3 calculation because N1 will have the same conditions. What do you think about this?

 

[SnTMan]

aard, obviously you need to check all 1 thru 4 for the connection to the shell, head, whatever it is. Calcs 1 thru 3 will apply equally to the other necks, and if of equal thickness will not need be performed.

For the cross, per Sec VII, Div 1 rules its' rating is the same as a straight piece of pipe of equal dimensions and material. No calculations concerning the cross need be performed.

Regards,

Mike

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

 

[TomBarsh]

The cross seems to be a standard B16.9 component. Under ASME Section VIII Div 1 it can be accepted as a standard pressure part with pressure rating (MAWP) determined as that for an equivalent straight pipe. See UG-44.

Thus (in my opinion, and based on a few seconds reading and a glance at your sketch) I don't think you need to perform any calculations for the cross ...other than to determine MAWP of the equivalent pipe, and if that's good, you're good to go!

Now, COMPRESS provides some of the standard components from B16.9, such as elbows, pipe caps, maybe another thing or two. I have long thought that it could provide possibly all such components, the rating is easy when done using UG-44. Creating the visual representation is a bit more problematical. But we may get to that some day.

For your case, I imagine that you need to assure that the cross is acceptable, and that the attached piping and flanges are acceptable as well, all under VIII-1.

In COMPRESS you "might" model N1, N2, and N3 in separate files, simply to confirm the pipes and the flanges (if all three are the same then consider that).

For the cross, model a piece of the equivalent straight pipe and determine the pressure rating.

This does leave the question of MDMT rating unaddressed. But lunchtime is over and duty calls.

Disclaimer: yes, I do work for Codeware but my opinion does not represent that of the COMPRESS publisher

 

[aard]

Thanks guys your comments helped me to solved my problem. The point that no calculations concerning the cross need be performed according to UG-44 clearify all my doubts and turn my doubt in an easy to solve problem. I just have to check that pipes and flanged attached are acceptable as you both agree.

 

[Jano6924]

It would be nice if Mr. Tom Barsh shares some light on how to determine the rated MDMT for this cross.

Hope you have the time to do that.

Regards.

 

[SnTMan]

Not to speak for Mr. Barsh, but..

See UG-44.

Regards,

Mike

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