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Design or calculations for davits

Design or calculations for davits

Design or calculations for davits

(OP)
Does anyone know of a spreadsheet or any information that would take you through a step-by-step process for calculating and fabricating davits or manways?
Steven

RE: Design or calculations for davits

Sorry snuffy, I don't have the spreadsheet you need, but the davit calculation is only a simple structural calculation for the davit arm and the arm support brackets. In retrospective, I have never calculated any davit for a nozzle cover, used only 'standard' designs. I have only designed larger lifting devices attached to the vessel or platforms to service the vessel appurtenances, using local guvernment regulations for lifting devices.
As for manways, I used ASME VIII calculation for nozzles.
Cheers,
gr2vessels

RE: Design or calculations for davits

I also use "standard" davit arms. They are sized mainly by the diameter of the manway or nozzele. For larger manways or heavier nozzles, the arm is constructed with a brace and thicker materials etc. I have some schemes. Please send me a PM and I can send to you what I have.

RE: Design or calculations for davits

Refer to: Pressure Vessel Design Manual by Dennis R. Moss - Procedure 6-1: Design of Davits

RE: Design or calculations for davits

I agree with Gr2vessels comments about a simple structural calc. I made a spreadsheet for calculating custom davits for large covers (I just did a 54" dia 3200# cover w/ davit) basically I do the following:

-look at the stiffness a cantelever beam - using moment of inertia etc... (I usually use a pipe or I-beam)
-then Caclculate the deflection of the beam
-Calculate the maximum moment
-check max shear
-check the above values to allowables
-then I check the attachment "clip" using the design loads (I use Pressure Vessel Design Handbook by Bednar)
-then I check my weld sizes/strength and make sure the vessel can handle it.
-for particularily large covers I will back it up with a quick FEA

As far as manways - it really depends on what you need (required ID, design pressure/temp). It can be a simple pipe with flange, a heavy forged ring with blind tapped holes, a special pressure seal design, or others.

RE: Design or calculations for davits

(OP)
Thanks Guys, I will check it out. I was asked to design a davit for a specific vessel. So I wanted to set up a spreadsheet that will give the combined stresses to fit the davits.

RE: Design or calculations for davits

There is "bearing stress" did not get mentioned for davit design.
By the way, many companies and even PIP standard VEFV1117 have davit details up to 24"-600#. You do not need to waste your time to prove your design if the weight and moment are within these standards.

RE: Design or calculations for davits

I tried to but could not find PIP VEFV1117 - where might it be available?

RE: Design or calculations for davits

Give me your mail id, i have one excel file, hope that will help you.

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