Hi all while designing a tall pres 1

[rajeev383]

Hi all
while designing a tall pressure column I came across a situation to use stiffener rings. As a cost optimization approach I was trying to use the internal rings provided for placing packing trays as my internal stiffener ring. Is there anything wrong with my approach?
Thanks in advance

 

[mk3223]

IMO, it can be a design alternative as one design is to meet the requirements of the process design and the structure integrity. As for the cost concern in terms of the design and fabrication, it may not be a substantial saving.

 

[dhengr]

Rajeev383:
Can the inner stiffener rings corrode so you might lose shell stiffeners over time? Otherwise, as long as you design for whatever loads/stresses the multi function inner rings might see, it seems there might be some savings in not needing an out set of stiffener rings, not an insignificant cost. I don’t know what prohibitions the ASME codes might put on this arrangement.

 

[r6155]

rajeev383
Yes, you can use this design

Regards
r6155

 

[PVDEngg]

rajeev383, since you have not specified code of construction in your question and since it is a column; I suppose it would be as per VIII.1.
Please refer para. UG-29(b), UG-29(C). This talks about stiffening rings welded on inside surface of vessel.

 

[DSB123]

Does the packing weight deflect the "ring" support such that they are not "in-plane"? If so their ability to resist loading will be compromised.

 

[mbt22]

Also check with the client, they may not want structural packing supports to constrain what they due in the future when the inevitable debottleneck or repack with the latest shiny packing comes along,

Matt

 

[marty007]

This also adds complication when it comes to inspection. Remember, the rings are a pressure part.

With rings located on the outside, the main pressure boundary can be thickness examined from the outside using UT.

With rings located inside, now access must be made available on a regular schedule to perform thickness examinations of the internal rings.

This should be discussed with the customer.

Cheers,

 

[saplanti]

In the process vessels the use of inner and external rings are very common for the purpose. Some cases the vessel is subject to vacuum and you need to use reinforcing rings not to increase the vessel wall thickness, and they are mostly regularly spaced. The rings can be used internally in case there is no obstruction or corrosion/abrasion issue.

Inner ring are mostly used for internal equipment connections. and they introduce the wall additional local stresses under the loads. The loads can be sourced by the weight of the equipment and/or differential pressure between the chambers and/or weigh of process liquid.

If you use them combined you will not be able to design the vessel by hand any more. You need a FEA software to go through all the load cases accurately and find stresses and strains in the localised areas to evaluate. For this application you need to know what you are doing.

I understand from your question you are not a competent engineer for the purpose. Therefore I would not suggest you to use the same ring for different purposes at the same time, and even if you use both inner and external stiffeners on the vessel wall I would pay attention that they are not in line and separated with their effective distances not to involve in the stress combinations which may become very complex.

 

[r6155]

External ring obstruct the inspection if automatic crawler systems for continuous ultrasonic thickness measurement is used during in service inspection.

Regards
r6155

 

[r6155]

If tray support can be used also as reinforcing ring to resit external pressure (partial vaccum) hence is not a good engineering practice to disregard this advantage by adding external reinforcing ring.

Regards
r6155