Pipelay Barge Stinger

[pipeline058]

I know that the rollers on the stinger of a laybarge will be fixed in a determined position before laying.
But is the stinger itself is fixed either?

If the water depth changes a lot along the route (e.g. form shore approach to 100m water depth), do they pull stinger a bit upward/downward (rotate it around the hinge and change its angle)?

the stinger arrangement suitable for 100m may not be good for 40m water depth, so how they manage it?

 

[atedionyahoo]

I understand your case is S-Lay, thus during pipelaying analysis, it is decided on the follwoing main parameters for various water depths:

1) rollers positions and stinger angle
2) tension on the tensioners

in case changing of the above item 1 during the operation is not desired, you can easily change the tensioner to reach the allowable condition (i.e. allowable strain / stress as laying analysis criteria).
Of course perhaps the capacity of tensioners are inadequate and it is necessary to change item 1 parameters during the operation.

 

[pipeline058]

Yes Atedionyahoo,

The tensioner is the best and first option...
but my question was pointing another problem

if you are going to start from shore approach, and the stinger is set up for laying in 100m water depth, then the stinger tip will be somewhere 15m under water.
so, you should continue shore pulling to about 20m water depth and start laying from this depth (otherwise the stinger collision with seabed)

to optimize it, is it possible to rotate the stinger around the hinge, e.g. 5 degree upward, then get closer to shore and start laying there. later on, when you reach to area with water depth of 30m, rotate stinger back to its original position.

RELOCATION OF ROLLERS DURING OPERATION (WHILE PIPE IS ON STINGER) IS NOT PRACTICAL...what about stinger rotation??

 

[BigInch]

The idea for an articulated stinger has been around since at least 1969!

The Cherokee that worked for me on GLV144 in 1982 has an articulated stinger in which the segments form angles according to the ballest held in each segment,

http://www.globalind.com/Documents/Operations/Vessels/CHEROKEE.pdf

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[pipeline058]

So, BigInch...they named you as MASTER OF TIPS truely!

Again I do agree with you that the problem is already solved. but in my case, the nominate laybarge are not equipped with articulated stinger.
with articulated stinger, you have actually two options for stinger length...but what if the stinger length is fixed?

Could you help me by straight forward answer to this question: while pipe is on stinger (during laying), is it possible to rotate stinger around hinge (using ballast or winch system of stinger)? if no, shall the pipeline be abandoned, the stinger configuration changed and pipe recovered and go on???

 

[BigInch]

There are a number of roller adjustment and buoyancy control methods. Check with your contractor. And some stingers have no curvature. Its possible that no rotation of the stinger may be needed at all. In shallow water the required curvature will be minimal and the pipe may not follow the entire length of a curved stinger, lifting off before reaching the end. In deeper water more curvature is required and the pipe may more closely conform to a full length curved stinger profile.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[GSUUS]

See attached some presentation about Slay calculation and also stinger setting. It may help.

http://rapidshare.com/files/349620599/AOE-PipelayAnalysesConcept-Rev02.pdf