Davit arm design
Davit arm design
(OP)
I need information about davit arm design. Davit shall carry a 30" CL900 blind(~1800kg weight.)used as bolted cover for a vertical vessel. Any help(Company spesific designs, design guides, etc.) will be useful.
Thanks
Thanks





RE: Davit arm design
You can refer to chapter 6 of Pressure vessel design manual by Dennis Moss , Third edition.
RE: Davit arm design
http:
RE: Davit arm design
www.pip.org
The document you would be interested in is "VEFV1100"
RE: Davit arm design
RE: Davit arm design
No 11echo, any reputed vessel fabricator will not deny to take the responsibility of ANY part of vessel fabricated by them. Vessel fabricator will check the design provided to them and if found okay they will take the responsibility.
If they find any gaps in design they come back to the purchaser highlighting the gaps.
RE: Davit arm design
What if this isn't a reputed fabricator?
I would expect a good fabricator to take a look at external custom designed components like davit arms. But what about an average fabricator.
I have never come across a fabricator that checks the designs of complete externally designed, drawn and certified vessels.
For a large high quality fabricator I worked for, if a customer supplied professional fully certified fabrication drawings there was no need nor payment to carry out yet another design check. In one case this did result in a sub chamber imploding during testing, however the customer supplied a full set of checked, approved and 3rd party certified, drawings.
RE: Davit arm design
When I worked at fabricators, we always checked to make sure the vessels were properly designed and meet code requirements in fabrication details, even if the client is big and reputable. If you take other people's design for granted, you could be in big trouble.
BTW, PIP does not cover 900# manway davit.
RE: Davit arm design
I guess I would expect that a "good" fabricator would spot check customer supplied designs for non-code components such as the manway davit being discussed. They've seen plenty of designs, and if the given design is substantially weaker in some respect, that should raise a red flag. How many vessel fabricators run numbers on the adequacy of components like tray support rings? But I'd bet that if I had an 8' diameter column and specified a tray support ring that's 1/16" thick I'd get some communication back from the fabricator to make sure I was positive that's what I wanted.
I would expect the fabricator to do his U-2 duty of checking the Code compliance of the Code components of a provided design. I've had fabricators "adopt" my calc's by putting their title block or logo in addition to or instead of mine. That's fine - as long as they either satisfy themselves that my design is reasonable (not "exactly right") and are willing to trust me with their liability.
jt
RE: Davit arm design
RE: Davit arm design
Moss's book and PIP document helped very much. I almost completed the design but some problems remain.
Davit support to flange(not blind) connection. Davit support can only welded to WN flange. WN flange is not a cylinderical surface thus using Moss's way a bit problematic. But i also think using FEA is an overkill. I have to find another way for calculating welded connection or make some (conservative)assumptions and wait the proof test. Any idea, comment or guidance on this matter?
sorry for the quality of the sketch :(
RE: Davit arm design
the distance between the plates is not set in stone
RE: Davit arm design
Have a good day