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# Pipelay Tensioner

## Pipelay Tensioner

(OP)
I am working on a project in which we are laying 10" grade B sch 80 pipe in depths of 10-200 ft of water (no concrete coating).  Anyone have suggestions on the tension required or where to start on the calculations for this?  Future requirements would be going up to 16" pipe.
Replies continue below

### RE: Pipelay Tensioner

For estimating purposes just assume its a catenary "string" hanging under its own weight(no pipe stiffness) with a tangent to the mud line.

**********************
"The problem isn't finding the solution, its trying to get to the real question." BigInch
http://virtualpipeline.spaces.live.com/

### RE: Pipelay Tensioner

(OP)
If I am understanding you right, this would give the tension required too prevent buckling in the sagbend region.  Is the stinger ignored for the sake of determining tension?

### RE: Pipelay Tensioner

(OP)
Another question regarding the stinger.  I had read in at least one of the text books that there is a straight portion between the departure from the stinger and before is assumed it's catenary form.  Is there a way to determine this portion or is it just ignored for calculation purposes?

From what I am understanding for speccing the stinger, we have the tension established to handle our deepest depths and then build a stinger that will guide the overbend until its departure angle equals that of the sagbend catenary.  The distance and curvature to this point is the shape of the stinger?

### RE: Pipelay Tensioner

For deeper waters assume the end of the stinger is tangent to the cat.  For shallow water, you'll be able to estimate the shape using a cantilever beam with a fixed end tangent to the bottom and free end deflection upwards towards the barge.

**********************
"The problem isn't finding the solution, its trying to get to the real question." BigInch
http://virtualpipeline.spaces.live.com/

### RE: Pipelay Tensioner

(OP)
BigInch,
Do you have any experience on the cost of a stinger?  I have a few companies getting back to me on a quote, but I have someone here looking for a very rough ballpark number by Monday morning.  We would be looking at a stinger with about 100 ft in length.  Either A frame or ballast would work for quoting purposes.

Thanks,

### RE: Pipelay Tensioner

No, I've never worked for an offshore lay contractor where'd I'd have that kind of data.

**********************
"The problem isn't finding the solution, its trying to get to the real question." BigInch
http://virtualpipeline.spaces.live.com/

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