concrete mattresses for pipeline stability

[billsumner]

Does anyone know of any published papers or methods that I could use to design flexible mattresses to be laid over subsea pipelines? They provide increased stablity against currents and waves but seem primarily to be used for impact protection for short lengths of lines near platforms.

These are of two types - the first looks like parallel logs; it is laid parallel to the pipeline axis - and the second is made of square blocks; it can be laid over tees and bends. Both sorts have different concrete densities and block thicknesses but are held together along the middle with polypropylene rope cast into the concrete.

I have a sinking feeling that this information is deemed to be proprietary knowledge by the manufacturers.

 

[DrillerNic]

there are a whole pile of papers devoted to the hydrodynamic effects on a pipeline from currents and from waves for pipelines on the seabed, partially buried, in trenches atc, for different soils and so on.

I was arware of a method of stability analysis (Veritec RP E305), where cetain dimesionless parameters are caluclated for a given pipeline and then compared to curves in the standard, to give a required submerged weight for stability. I'm afraid I don't have a copy of the standard now (or know if it still exsits!)

 

[billsumner]

Thanx DrillerNic,

I have lots of info on the pipelines themselves - including the AGA/PRCI software package.

But what I really want to know is how the mattresses behave. Are they deemed merely to add weight to the lines? I would have thought that the draped shape would modify the coefficients.

This information is likely to be discussed in a paper on them.

Bill