Re: [PipingDesign] Column Reboiler problem

From: <Pete>
Date: Fri Sep 13 2002 - 18:20:00 EDT

Tanmoy,
I am not a piping engineer, but my experience with larger pipe systems is from the Navy. In the shipyard it was always amazing to me when we removed a pump for overhaul, replaced the pump and proceeded to bolt up flanges that the flanges were most often not where you wanted them. We used the term "sprung " for the situation. As for our solution - often in haste and poorly supervised we would force the flanges togerther. I know now how bad that was. If the distance was alot we would cut and re-weld the pipe. I mention all this because it was a relatively comon occurance. I might guess the support system is alot different than on a " land" base. I would assume the ship flexes with time and heavy seas. I was wondering from the experts - Do pipe configurations "spring" any when released from the nozzles and hangers ?

Pete

   Hi all

   This is a problem observed and raised by one of my friend. My views are as    below

   Information is not complete. Further information like full detail of the    column at least the distances of the nozzles from bottom tangent line of the    column is required.

   However it looks like it is not a stress problem as there is mismatch of two    nozzles. If it was a stress problem both the nozzles should have deflected    same way and there shouldn't have been any relative displacement. Possible    things are

  1. the nozzles were offset at the beginning itself and forcefully joined by some tricks. (most likely)
  2. the tower and the reboiler were not at the same temperature which is less likely.

   Am I correct? What do you think?

   Thanks

   Tanmoy Saha
   Kellog Brown & Root, Singapore.
   Ph. 6422 2535
   Email. Tanmoy.Saha@Halliburton.com

   Problem:

   COLUMN

                Reboiler
                                                         80" connection






   Reboiler
   Flange

   4 Lugs
   2 Springs
     per lug

   There is a column with a reboiler connection of 80" size. The reboiler is    supported on 4 lugs and there are 2 F type springs below each lug. Each    spring takes a load of about 10 tonnes. The reboiler is very heavy. The    reboiler is supported on a separate concrete structure.    After about 8 years of operation client found out that the 80" connection    nozzle flange and the reboiler body flange were leaking. So to replace the    gaskets the reboiler was disconnected at the the 80" nozzle flange and the    body flange. When they were refitting the removed part of the reboiler back    to the original position, they first connected the 80" nozzle flange. Then    they found out that there was 10 mm gap between the two body flanges.    Nobody is able to guess what happened. The lugs are still touching the    spring load flange. The pointer on the flange is at topmost position and not    at center.
   There are 30" piping connections on the downward part of the reboiler.

   Can u suggest any reasons what could have gone wrong ??

   [Non-text portions of this message have been removed]

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[Non-text portions of this message have been removed] Received on Fri Sep 13 18:20:00 2002

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