Hello friends,

I am trying to design a pressure vessel of 20" dia having bolted cover. One end of the vessel has a elliptical head.
1 - How do I decide what is the bolted cover class? What should be the type of flange used on the vessel body ,mating with the cover ( 600 lbs WNF or LWN) customer hasnt mentioned any thing.

2 - the bolted head has a davit for lifting & holding the cover. How do I design a davit for this ?

appreciate a quick response.

thanks,
manoj

Answering your questions with questions, sorry.
1a. How do you define class of a bolted cover? What requirement do you try to meet?
1b. What is the service? What are the ratings? What is the size?
2. Lifting devices always are provided for in local law. Where on earth will your vessel be operated?

Cheers

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Konrad Anikiel

Manoj,
If you want to design a flange that is going to be fabricated and is not an external connection, it doesn't have to follow any standard. If you want it to be a raised face flange, use Appendix 2. If you want it to be Appendix Y-type flange (wit an O-ring, for instance), use Appendix Y.
But if you don't want to fabricate it, if you want to buy an off-the-shelf flange, say B16.5, then use it in accordance with B16.5, so take the right class based on pressure+temperature+size+material.
Apparently, you didn't say much about temperature, size and material. I can't help much. (oops, sorry, in the beginning of your first post is the size: 20")
"Where on earth" meant in which country. What is the place of installation for your davit? If you are to design and build a lifting device, be aware that you will have to follow some local regulations.


PS. Hooray! this is the 2222nd post in this forum.

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Konrad Anikiel

Manoj,

I will try to summarize Akonrad mail in simple words (hopefully).

1. If standard flange is used for bolted cover, it will be as per ASME B 16.5. Rating will be same as of your vessel body flange (600# as per your mail).

2. If custom designed flange is to be used, it will be as per ASME Sec VIII, to appendix 2 or app Y.

3. It does not matter whether bolted cover matches with WN or LWN body flange.

Hope this clarifies.

Regards

Sanjeev Thanks for your response.

I also want to know what design rules to follow for an Integral davit design.( picture attached)
thanks,
Manoj[/img]

Manoj,

You need to probably open any design hand book or your college days book to design davit arm since it is not covered in ASME or other design codes such as PD 5500 etc.

As already mentioned by Akonrad, you need to take care of local regulation for the lifting equipment, generally for factor of safety. In general SF of 2 can be considered.

Most of the engineering companies have standardized davit design based on flange size and the rating/ weight & orientation (horizontal/ vertical) and can be used as reference also.

Regards

Guys,
lifting devices, depending on the place of installation may or may not be under a bunch of formal requirements, like design/designer appraisal, manufacturer certification, personnel qualification, material certification, authorised inspector's witnessing, proof loading, periodic check, etc. Without recognition of regulatory requirements, it's misleading to say "in general SF of 2 can be considered". It's not so simple. There is no "in general". Just think what happens if it breaks and harms anyone. Will you say to the prosecutor "in general I did it right"?

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Konrad Anikiel