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Pressure Vessel Support Design

  • 1.  Pressure Vessel Support Design

    Posted 07-05-2020 02:06
    Hi, I am Chamuditha from Sri Lanka,

    For an assignment of mine, I have to design a pressure vessel for polymerization of styrene. My pressure vessel is cylindrical and has two holes on two ends for the stirrer and for inspection and drainage. It is 40ft long and 20ft diameter. I designed the openings such that pressure vessel should be kept vertical but then realized the I should have designed it to be kept horizontal. No I cant change the orientation.

    Can anyone suggest me a type of support that I can use? The problems I have are as follows.

    1. Cannot use a skirt support since I have a drainage at the bottom
    2. For brackets to be kept on beams, I feel like it is too large
    3. If I am using legs, the legs must be high enough for the drainage pipe to be fixed, and a man to enter, but since the vessel is too large, I am afraid using long legs will lead to buckling.

    Please give your insight on this.

    Thank You

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    Chamuditha Benaragama
    University of Moratuwa
    Veyangoda
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  • 2.  RE: Pressure Vessel Support Design

    Posted 07-05-2020 03:50
    Edited by Vittal Kamath 07-05-2020 03:52
      |   view attached
    Hello Chamuditha. How are you doing? Hope everything is going great!

    Since you have designed your pressure vessel to be vertical in alignment, two ideas immediately strike me. These two ideas are based on the assumption that the product from the pressure vessel will be transported to the second stage of the polymerization process. This is because the polymerization of styrene is controlled by a two-stage polymerization process.

    1. Firstly I am thinking about using leg support for holding the vertical vessel. You had mentioned that a large leg that would support the tremendous weight of the vessel could be prone to buckling. However, this risk could be prevented through the proper selection of the material as well as the design. Multiple legs could be designed which take into account the center of mass as well as the force to be endured in order to prevent mechanical fatigue as well as the vessel being unstable. I have uploaded a paper below which supports this idea...
    2. Another idea is to drill the hole in the vessel not at the bottom but just above the bottom. This would allow for a skirt support to be installed in your design. Drainage would also be possible through this method, however; I am not sure if this would align with your design and plan.


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    VittalKamath
    Undergraduate Student
    B.S. Chemical Engineering
    Iowa State University
    Email: vgkamath@iastate.edu
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  • 3.  RE: Pressure Vessel Support Design

    Posted 07-05-2020 08:02
    Hello Vittal,
    Thank you for your insight. I have to check with my assignment coordinator to see if I could change the position of the manhole, because I already have submitted the report on vessel openings. According to your knowledge, just forget about the openings. What do you think is the best support for a vessel to be kept vertical, with a diameter of 6m and height 12? Would you choose skirt or legs?

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    Chamuditha Benaragama
    University of Moratuwa
    Veyangoda
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  • 4.  RE: Pressure Vessel Support Design

    Posted 07-05-2020 10:22
    Traditionally skirt supports are used for large vertical pressure vessels; however, that doesn't mean that it would be unsuitable to use leg supports. You could use the 'Bednar's guidelines for leg supports' to distinguish between small and large vessels. Engineers would usually use skirt supports for large vertical vessels. I would say that since your vessel is classified as large, multiple legs could be installed at the base.

    Unfortunately I am not aware of particular materials that could be used to support the vessel. You will have to look for materials with good mechanical properties (tensile strength, yield strength, and young's modulus).

    Take a look at this website: Skirt support vs Legs

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    VittalKamath
    Undergraduate Student
    B.S. Chemical Engineering
    Iowa State University
    Email: vgkamath@iastate.edu
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  • 5.  RE: Pressure Vessel Support Design

    Posted 07-05-2020 10:25
    Hey Chamuditha, how are you? I hope you're well.

    I always like to base my answer on theoretical books/articles. So, I searched for a few books that may help you on your assignment:


    According to what I've read in these two materials I linked, bracket supports are normally used for vessels of smaller height. Then, I went to understand what is the definition of a tall pressure vessel. According to Boardman Inc. (source here), "Tall pressure vessels are generally defined as those where the height to diameter ratio (H/D) is more than 15". So perhaps you should consider using brackets as supports.

    Also, there are many alternatives for vertical pressure vessel support. Acceptable designs include: angle legs, hollow tube supports, WF supports and complete support skirts. I extremely recommend you taking a deeper look in the other options you didn't say in your initial post.

    I'd like to thank Vittal for his great insights, and I believe you're coming to a conclusion. Personally, I guess I'd go with legs or brackets, considering the H/D ratio. To choose between both, I'd do a more extensive study.

    I wish you the best and good luck with you assignment! Don't hesitate to message or email me with any doubts!

    Best regards,


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    Bruno Neves
    Student Chapter President at AIChE UFRJ
    Latin America Regional Liaison - ESC
    Publications Subcommittee/Student Central - ESC
    Chemical Engineering Undergraduate - UFRJ
    brunofra@eq.ufrj.br
    Rio De Janeiro - Brazil
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