Floating of a 1.6mtr x 19mm x 60 mtr steel tube

Click For Summary
SUMMARY

The discussion focuses on the procedure for floating and submerging a 1.6 m x 19 mm x 60 m steel tube in the Mekong River using two tugs and cranes with a 42-ton capacity. The tube will be flooded through a 1" valve at the top and a 2" valve at the bottom, with concerns about achieving even submersion and managing back pressure as the tube descends to a final depth of 6 m. Recommendations include holding the pipe at a shallow depth during flooding to prevent instability and suggesting a staggered valve submersion strategy to expedite the flooding process.

PREREQUISITES
  • Understanding of fluid dynamics and pressure management
  • Familiarity with crane operations and load management
  • Knowledge of valve types and their applications in fluid control
  • Basic principles of buoyancy and submersion techniques
NEXT STEPS
  • Research fluid dynamics principles related to submersion and buoyancy
  • Learn about valve operation and back pressure management in fluid systems
  • Investigate crane load management techniques for underwater operations
  • Explore best practices for welding and maintaining structural integrity in submerged environments
USEFUL FOR

Engineers, project managers, and construction professionals involved in underwater construction and pipe installation projects.

sbgce
Messages
1
Reaction score
0
Appreciate any comments regarding the following:-(I am not an Engineer)
We intend to launch (Mekong River) the subject steel tube (12mtr pipe welded together using the collar sleeve method) Flanges / gasket will be fitted at both ends of the tube. The flanges will have a 1" valve at the top and a 2" valve at the bottom. The plan is to float the tube (using two tugs) along side a barge then have two cranes(42 ton capacity each) to tie onto the pipe say 10 mtr from each end. once this is completed both 2" lower valves will be opened and then the 1" upper valve will be opened to control the flooding speed. final water depth when pipe is sunk (but still boyant is 6mtr - The river flow volocity will be approx 2mtr/min - I was considering welding some kind of baffle arrangment inside the tube (for stability) but as it has been coated I don't want to damage this . I am concerned that I may not get even (level) submerging when opening the valves. Also once the 1" valve is under water and the tube slowing submerging down to the 6mtr level - what effect will this have on the 1" bleed valve (back pressure??) At the 6mtr level the barge (by using winches) will slowly move the tube into position to connect (by Flanges) to a stationary pipe coming from the river bank.
Any comments would really be appreciated.

Thanks
 
Engineering news on Phys.org
sbgce: By the way, the unit symbol for meter is m. E.g., 1.6 m, not 1.6 mtr. Also, always leave a space between a numeric value and its following unit symbol. E.g., 1.6 m, not 1.6m.

I think the pipe flooding rate will slightly decrease after the upper valve submerges (but this slight change in rate might not even be noticeable). And the flooding rate will continue at this same slightly slower rate thereafter, regardless of the pipe depth.

Therefore, I would say, let the upper valves submerge just below the water surface, and hold the pipe at that location with the cranes, and wait, until the pipe essentially finishes flooding. Now, with the pipe completely flooded, there is no opportunity for tilting (instability). Therefore, you can now proceed to lower the pipe to the desired depth.

PS: I think you can perhaps expedite final flooding by keeping one of the two upper valves, say, 100 mm below the water surface, and keeping the other upper value 20 mm above the water surface. Then, when air stops flowing out of the second upper valve, you can submerge the second upper valve, and hold the pipe at that location, per paragraph 3, until air stops escaping.
 
Last edited:
Welcome to PF, Sbgce.
I'm pretty sure that I'm missing something here, because the scenario doesn't make sense to me. Why not just leave the pipes open, walk them into position with the barge cranes, and slowly lower them into position? If you're going to flood them anyhow, why would you bother to water-proof them in the first place?