Horizontal Pressure Vessel Supported by 2 sumps

[eronevich]

Good Morning,

I have a question about a pressure vessel. The drawings I have in front of me show a 42" OD (20' long) Horizontal pressure vessel with two 20" OD sumps. (1440 psig 120°F)the kicker is that there are skirts on these two sumps supporting this vessel. There is no saddle support, just the skirts on the sumps. Has anyone seen anything like this? Is this becoming a standard industry practice??

 

[JohnGP]

I can't imagine it's becoming industry standard, and I can't imagine a situation where I would need such a vessel. It would be a bit difficult to have a sliding sump, so there would be some more loads to analyse.

 

[MJCronin]

Very cool..... probably some kind of award winner !!!

I agree, if there is any kind of temperature increase, one of the skirts must be able to slide.

Certainly one of a kind...... I cannot imagine a chemical process where two separate sumps are needed. Does the tank have multiple internal compartments ?

Can you post any pictures or images ?

 

[vesselguy]

This is definitely not standard practice.

This is no different than the steam drums I've seen before. I remembered in 1989 when I was asked to check the local stresses on a horizontal drum that is supported on 3 or 4 (can't remember exactly)riser / down comer pipes.

In your case, if the design temperature is only 120°F, then correct me if I'm wrong, but a quick calc tells me your longitudinal thermal expansion of the whole shell from Amb temp of say 50°F to 120°F is only 0.11 inch. I don't know how long your boots are, but I can guess you will have only a small moment on the boot-to-shell connection and it should be able to be easily compensated by an Appendix 1-7 calc. No worries. The vessel certainly looks strange but workable.

 

[LSThill]

eronevich (Petroleum)

Please provide PHOTO OR DRAWING

 

[4Pipes]

I agree the MJ - Cool.

I am all for innovation but you still need to account for differential expansion even if it is only a few mm. Every vessel I've seen on refineries and process plant has both fixed and free saddles welded down with rust after a few months. It is probably only over designed saddles that prevent more vessel failures by being able to deflect the supporting structure.

The mini skirts are also going to get in the way for inspection, operation, maintenance access for drain valve on the sumps.

 

[eronevich]

Here is a drawing of the vessel

 

[gr2vessels]

Interesting;- some coalescing filter with not much room to fit two saddles;- heavy quick opening head which might put some strain on the shell and the saddle if fitted. I'm sensing some additional stability using that unusual skirting arrangement. This could also be a better arrangement for the expected heavy slug flow on the inlet, where the saddle would see additional loads.
However, my preference would still be a high supporting structure and two short saddles, let the boots hang in there.
My two cents..
Cheers,
gr2vessels

 

[saplanti]

I might be mistaken but the drains do not look like at the lowest points(heads) of the sumps. How often they are going to take the bundle out and clean the sumps?

In case the fluid or accumulation in the lowest points are corrosive, it may be causing more corrosion on the sump heads and inspection of heads during the operation will not be possible due to the ful enclosure of skirts. I guess most of the refinery operators do not like this.

This is my opinion only.
Regards,

Ibrahim Demir

 

[MJCronin]

So.....

If I understand your vessel layout correctly, a couple of different things are happening within the vessel ( multi-compartmented ?)

And the two sumps serve two different process purposes on a horizontal vessel ?

Is that correct ?

The multiple purpose of the vessel is what makes it unique.

-MJC

 

[4Pipes]

I would want some very serious design justification for this. As I said, I am all for challenging the norm but this does not look right. The only positive aspect is that the pressure would be acting against the radial inward punching load from the mini-skirts. The nozzle loads from 28" flanges could be totally out of proportion to the strength of the 20" branches onto the drain. The circ bending and forces on the 28" nozzles would have to be absoloutely zero.

I'd prefer to see mini-skirts wrapped around a decent pair of legs.

 

[MJCronin]

Also,

I see no process nor structural reason that the horizontal vessel must be supported from the two skirts.

It seems to me that the decision to support this vessel from the two sumps must have come from a madman.... perhaps even an MBA....

The vessel configuration could be slightly altered to allow for the more conventional support - two saddles.

-MJC

 

[vesselfab]

those gas compression companies will do strange stuff to sqeeze the equipment on a skid.

this one has no thermal expansion concerns and gas probably has very little liquid in it.

if the two sump nozzles are checked for the loading on them both vertical and motion for shipment, there most likely will be no problems.

just not what we are used to seeing. another foot of shell would make room for the two saddles and would be much better design as well as more asthetic.

 

[superdaigle]

This is common for filter/separator vessels.

The most common arrangement is still saddle supports with sumps connecting to a two compartment horizontal boot underneath the main vessel; however this arrangement exist to keep the equipment accessible via grade without having to supply an access platform.