Hanging Bundle

[CuMo]

Hello all!
It's been a while since I last visited.
Anyway. Straight to the topic.
I am designing a 20" NB reboiler from scratch (I am doing just the mechanical bit).
The exchanger is vertical and the shellside inlet N3 is located near the top tubesheet as it can be seen from the drawing:

http://i.imgur.com/Ji650uj.png

I am supposed to fit an impingement plate at N3 but due to the tight design I can't really play much with the tie rods positions.
Would it be a problem if all baffles and spacers hang on the tie rods and their whole weight is taken by the nuts at the bottom?
Has anyone had an experience with this arrangement?

I just had an alternative idea in mind - weld the impingement plate inside the shell but then assembly becomes a bit tricky.
Or stick it inside the nozzle after consulting the thermal guy.

What do you guys think?
The nuts are M10 and theoretically should be able to take the weight of 5 baffles and some spacers. But I might be missing something.

Thanks in advance!

Design Code is ASME VIII-1 + TEMA 'R'.
Material - 316/316L

 

[marty007]

Can you consider impingement rods instead of a plate? Depending on your tube layout, this can sometimes work better.

 

[SnTMan]

CuMo, I don't think I'd be worried at all about baffles and spacers hanging off the tie-rods. They are both mostly holes. But, keeping in mind that the strength of a nut will normally exceed the strength of the male thread you could do a quick P/A calc for the tension stress in the thread if you wanted that assurance. That is a very common arrangement.

Not sure what's going on with your impingement plate, but if the tie rods are further apart than you'd like you can add ears to the plate to make it reach. I'd not put it in the nozzle if I could avoid it.

Regards,

Mike



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

 

[CuMo]

Thanks guys.
I did it the lazy way.
Imported a sketch from CAD to SolidWorks.
One baffle weighs about 4.5 kilos. 5 baffles = 22.5 kilos.
In worst case scenario baffles and spacers will weigh not more than 40 kilos together
which is nothing distributed on 7 off tie rods.
I might have been too cautious.

http://i.imgur.com/RTIMwJN.png

 

[EdStainless]

My only concern is when tubes bind in the baffles and you end up with non-uniform loads that are much higher than just the weight of the baffles.
I still think that it would work.
What are the MOC? Is this all stainless or some other highly erosion resistant material?
The last think that you need is have some of this cut by erosion and then causing a real mess.


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[CuMo]

Absolutely everything is stainless 316L.
Shellside is low pressure steam so environment should be pretty clean.
Is there really a chance that what you say can happen?
Cheers!