Orcaflex Analysis : Installation Pipe

Discussion in 'Hydrodynamics and Aerodynamics' started by thomasjo87, Jun 5, 2015.

  1. thomasjo87
    Joined: Jan 2015
    Posts: 14
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Paris

    thomasjo87 Junior Member

    hello fellow members,

    Need your help on a matter in Orcaflex...I need to find the hydrodynamic load acting on a pipe which is connected to the ship and performing an operation at a depth pf 20m....

    i modelled the pipe..imported RAO of vessel..modelled environment..connected end A to the vessel an kept end B free...but when doing static run, the pipe just rotates about the connection point on deck and becomes vertical on the ship deck...very strange...

    Any comments/suggestions on how to rectify? Can you help me ?

    Is there a method you would recommend to get the loads easier ??

    Thanks a ton...
     

    Attached Files:

    Last edited: Jun 8, 2015
  2. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    I don't use Orcaflex and know nothing about the software. So I can only make generalized comments, which might eventually turn out to be a nonsense...

    But here it is, the first uninformed thought that came to my mind - is the gravity defined correctly for the pipe, and in the correct direction?
     
  3. adada_subsea
    Joined: Jun 2015
    Posts: 1
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    Location: HOUSTON

    adada_subsea New Member

    Hi thomasjoe87,
    i have observed couple of errors in the inputs you've given, from the pictures posted.
    1. The number of segments is just 1? This means the pipe is not allowed to be flexible. So, try increasing the number of segments by varying the targeted segment length .
    2. Also, what sort of operation is expected to be erformed by the pipe at the mentioned depth . Is it a simple pipe lay, or is it pulled in using a winch ?

    Thanks
     
  4. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    Does the pipe have mass?..since how does the software know it is floating in air or water?...picking up D's point.

    If the fixity is hinged...then there is only the reaction load of the vessel on the pipe, at the hinge. Which related to its waterplane area. Since the pipe whether hollow or solid is in equilibrium, thus what are you trying to achieve? Since the pipe must follow the vessel.
     

  5. palgroth
    Joined: Jun 2015
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    Location: Norway

    palgroth New Member

    Hi! I believe this happens due to your infinity connection stiffness at hang-off. You have to pay attention to azimuth/declination/gamma when your connection stiffness is not 0.
     
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