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Forces on Ballasts due to Restraint against Pipeline Ovalization

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N G P

N G P

Structural
May 15, 2018
33
I have been designing a concrete ballast block for a subsea pipeline (flexible PE Pipeline with 1.8m dia SDR 26). As I understand, during installation and operation , there will be some deformation /ovalling of the pipeline owing to the below conditions.

* Bending of the pipes during lifting and due to self weight
* Bending of the pipe during installation and due to varying seabed
* Due to backfilling and application of overburden pressure on the pipe

Since the ballast blocks are provided at spacing of approximately 8m, pipelines will not be able to deform freely near the blocks. So,there would be forces on the ballast blocks and tension induced on the bolts connecting the ballast blocks. Some reference images are given below,
1_mbe4la_ercqzy.jpg
2_bkspeh_ehonzz.jpg


Does someone has any reference to estimate these forces. I have been trying to find it some books and codes (AWWA M55) but couldnot find any.

Thanks,
 
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What forces?

Your diagram shows over burden weights.

I'm a bit lost as to what you're during to do. 8m spacing with a ring on a 1.8m pipe is quite rigid.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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AWWA M55 focuses mainly on design aspects of PE pipes under internal pressure and soil loads, and does not cover this specific scenario of deformation due to subsea conditions and external constraints.

could provide guidance on estimating the forces:

DNVGL-RP-F109: Covers on-bottom stability and force calculations for pipelines with ballast blocks in subsea conditions.
API RP 1102: Provides methodologies to estimate the external load effects and the deformation of pipes due to soil and backfill.
DNVGL-ST-F101: This standard addresses subsea pipeline design, including considerations for bending, forces at support points, and the interaction with ballast structures.

R.Efendy
 
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