Saddle supports

[bogu]

I am currently working on a project where I have to support on vessel on top of another via saddles supports i.e. the bottom of the top vessel saddle is curved to fit onto the top of the bottom vessel. I can use BS5500 or zick for the, shall we say normal saddles but I am not sure how to go about the saddle attached to the top of the bottom vessel. I do not have access to FEA and normaly write a calculation sheet in MathCAD.

Thanks in advance.

 

[MJCronin]

bogu,

I assume you have two horizontal vessels.....you did not state this......I also assume that these might be stamped pressure vessels ?

I strongly suggest that you contract this work out to a company that has an ASME "R" repair stamp. Include the saddle design as part of the repair process.

Require dimensioned detail drawings from the contractor as part of the review approval cycle. Require ASME code approved materials even though the vessels may not be code stamped (this will incur a modest increase in cost)

You are not going to do this work "in-house" are you ????? There is a reason that ASME ( and other similar organizations require qualified repairs to stamped pressure vessels......


MJC

 

[jproj]

bogu:

I've seen this type of support before, but usually the saddles are not one piece..... normally the top vessel will have bottom saddles and the bottom vessel will have top saddles (both having flat plates at the contact point). Vessels are then held together by bolts. With this arrangement, I believe one can do Zick calc's. I would recommend contacting someone to help you design the supports... it's a lot cheaper than having the tank fail in service.

jproj

 

[LSThill]

Hi bogu (Mechanical)

Do an advance serch for Saddle supports

Leonard

 

[prex]

My first attempt would be at designing the saddle of the lower vessel so as it can transmit the load from upper vessel to floor without accounting for the presence of the shell of lower one. This of course requires that the lower saddle fully encircles as a ring the lower vessel. If you can satisfy this condition, then you should be OK and the calculation would be based on beam theory.
If this is not the case, but still assuming that the saddles are vertically aligned, the transfer of load from the upper to the lower vessel would be a local (also buckling) problem for the vessel wall: Zick doesn't treat this matter and I've never seen such a calculation. Sorry I can't be of more help there: you'll need to set up your own calculation method.

prex

http://www.xcalcs.com

Online tools for structural design

 

[jte]

bogu-

Sounds like what you have is an extremely common situation: A set of stacked heat exchangers. As the folks in the other responses have mentioned, get in touch with someone who has some experience in this type of design. There should be plenty - any shop which has ever designed a stacked exhchanger will be able to help.

jt

 

[bogu]

Gents

Many thanks for your responses but I have managed the talk the client into supporting the top vessel on a frame and consequently it has become quite straightforward.

Once again thanks for your responses.

Bogu

 

[chicopee]

BOGU, THAT WOULD HAVE BEEN MY RECOMMENDATION ALSO TO HAVE AN EXTERNAL FRAME INDEPENDENT OF THE BOTTOM VESSEL AND YET STILL HAVE BOTH VESSELS STACKED.

 

[rrobert]

I'd like to perform a spreadsheet of wrc107 /297 but I haven't any original copy of them to perform a correct conversion of graphics.
Does any one know if there are some pdf copy anywere ?

tanks in advance rrobert

 

[LSThill]

rrobert (Mechanical)

297 Local Stresses in Cylindrical Shells Due to External Loadings on Nozzles - Supplement to WRC Bulletin 107 - (Revision 1), by J.L. Mershon, K. Mokhtarian, G.V. Ranjan and E.C. Rodabaugh. August 1984, revised September 1987 (88 pp) (ISBN #1-58145-296-9) „Ÿ $72.00 (Note: Recommend you also order the Basic Document, Bulletin #107).


107 Local Stresses in Spherical and Cylindrical Shells Due to External Loadings, by K.R. Wichman, A.G. Hopper and J.L. Mershon. August 1965. March 1979 Revision (69 pp) (ISBN #1-58145-106-7) - $72.00. (Note: Recommend you also order the Supplement, Bulletin #297).

Leonard@thill.biz

http://www.thill.biz