Vertical Vessel Leg Support 1

[ShiningIND]

I am designing a small Vertical vessel. Client requirement is three channel Angle support legs connecting to the shell.

* Please suggest some design handbook.
* If possible I want a sample design calc of the same.
* What additional calc should be done if plate is bent in angle form?

Sorry for noob questions, I am pretty new to this field.

Thanks.

 

[dhengr]

ShiningIND:
You may be kinda ‘new in this field,’ but there is no time like the present to start learning. And, you won’t learn much very quickly if you keep being spoon fed, all the answers, details, calcs., etc. Any good pressure vessel text or handbook would be a good place to start. There are several good ones, the guys who do this everyday will chime in on this account. Henry Bednar, is a good author, and his handbook a good ref. book. One of us could just do it for you and send the solution to your boss, under your name. Start thinking through the problem, and tell us how you’d go about it, answer the questions that are brought up here, and we can critique you along the way. It might be a good idea if you asked one of your superiors if he/she would be your mentor, so you learn faster and have someone nearby who can look at the same drawings and specs., know the local codes, know the client req’rmts., etc. They should know what you know and what you don’t know, and offer guidance, so they keep you and the company out of trouble. Tell your boss that you are in a bit over your head and you do need his help and guidance. They shouldn’t just throw you in the deep end of the pool and tell you to swim, or else; nor should they spoon feed you, or you won’t learn anything for yourself.

What is a channel angle? Nothing special should be needed if you were to form a simple shaped leg out of plate, but why would you do that. Isn’t an angle shape kind of a weak and unstable as a column section? Why? Why wouldn’t you use a piece of round pipe or sq. stl. tube? Why? What are the loads and conditions that you should design for, what safety factors should you use? What are the codes you should be designing to? Where should you locate these three legs (why not four or more legs), so as to best handle the loads and transmit them to the vessel shell, and not overstress it. Should you put a re-pad (reinforcing pad) on top of the legs and then weld that to the shell? Base pls. and anchor bolts, of course, at the bottom of the legs. Should the legs be braced to better take any lateral loads? Why is it better to have the legs out near the OD of the tank? There are several important reasons that I can think of. Show us a sketch of the vessel and what you intend to do, with dimensions, sizes, good proportions, loads, weights & CG’s, any significant piping loads, etc. This is just a short list of the info. you need to start to gather toeven get started on solving your problem. Come back with a sketch and answers to these questions.

 

[ShiningIND]

dhengr,
Thank you for the reply. The present vessel I am designing won't go for production, Its a sample like report. And I am learning myself from scratch (No possible/available mentor).

*The vessel is subjected to compressed Air service with 20" OD & 17" (shell height) with two ellipsoidal dish ends.
*I am supposed to use 3x Diagonally welded Angle with reinf pad and base plate. Empty weight of vessel accounts to 209lb and no other loading's act (wind,seismic,snow etc.).
*The design code is used as per ASME BPVC.
*Legs are not cross braced.

Off topic: Is there an option to private message here to talk one on one?

 

[racookpe1978]

OK.

So, go design the tank. Weight, wall thickness, leg reinforcements, nozzles, pads (on the bottom of the legs), head thickness (top and bottom). Material specifications. You have the references. Go use them.

If you have no mentor, no boss, no plans to fabricate the tank, then what you decide will not hurt anyone if (when) it blows up if you underdesign it; and it will not bankrupt the company when it is too expensive to sell at a profit when you over design it.

 

[jte]

I'll second what racookpe said.

Off topic: Is there an option to private message here to talk one on one?

Not yet. Perhaps in the future. Perhaps sooner than you think.

 

[dhengr]

ShiningIND:
I’m not a pressure vessel design engineer by trade, but I’ve been involved with them a little bit of it over the last 50 years. I’ve had to deal with various codes at times. I am not very familiar with the latest minutia of the various codes you must follow, I do not have the latest editions on my book shelves. But, when I’m handed a part of a code, I can usually understand where they are coming from, the principles behind it, and what the general intent is. The truth of the matter is that the laws of physics and good sound engineering principles don’t change much from product to product, or when you move across a national boarder. Good common sense, good engineering judgement and experience, knowledge about materials and fabrication methods, etc. are very important, and often pretty interchangeable.

Who set the rules, the sizes, loads, other design criteria, etc. for your sample problem? That does not seem to be a particularly practical, real world, problem. It is not (may not be) a good learning problem because the size is so small, that the size itself introduces some unusual considerations. What would this vessel be for, other than compressed air, and at what pressure? Try me at rwhai at comcast dot net. Pick a real world vessel, the design principles will be those used every day in the pressure vessel industry, and material sizes, thicknesses, will be actual available sizes. The Pressure Vessel Handbooks or textbooks would cover most of these details and be a good place for you to start.

Have you had basic Engineering Mechanics, Strength of Materials, Machine Design, Pressure Vessel Design, Piping Design courses? Are you a graduate engineer, or what? Are you a student, where and in what kind of program? What work experience have you had within the industry? You have to have a lot of these basic fundamentals well in hand, or your want to learn will be a real struggle. I applaud your desire to learn something new, however.