Ducts, pipes : Influence of soil thermal characteristics

[Foudrette]

Dear All,

I work in the area of underground HV cable links design.
For underground cable ampacity calculation, it is necessary to take into account the thermal behaviour of the soil (this is one of the major parameters). IEC 60287 standard is commonly used to calculate cable ampacities. This standard is suitable for most of the ways of laying. But when you have to cross a road,a railway or a river the burial depth can reach important values (40 feet or 75 feet) for example.

If ampacity calculations are made according IEC 60287, results obtained are very pessimistic because it is assumed there is no change in soil thermal resistivity what is surely false. This leads to choose cable with very big cross-section (to reduce heat due to Joule's losses) what of course dramatically increases the cost of the cable and thus that of the cable link.

Someone in another forum (thanks to him !) adviced me to look for an answer to this issue in this forum.
Maybe some of you, working in the area of off-shore or pipeline engineering have already studied these problems of soil thermal characteristics simulation.
I assume thermal behavior of the ground is also important for the design of a pipeline...

Thanks for all of your help,
Marie-Hélène

 

[LSThill]

Hi Foudrette (Electrical)

Guideline for the Design of Buried Steel Pipe - July 2001

This guideline presents design provisions to evaluate the integrity of Buried steel pipe for a range of applied loads. It applies to new or existing buried pipe made of carbon or alloy steel; welded pipe; piping designed, fabricated, inspected and tested in accordance with an ASME B31 pressure piping code; and buried pipe and its interface with buildings and equipment.

http://www.americanlifelinesalliance.org/Products.htm#Guidelines

http://www.americanlifelinesalliance.org/pdf/buried_pipe.pdf

Seismic Fragility Formulations for Water Systems (2 parts) - April 2001

This state-of-the-art study provides comprehensive data on damage to water conveyance systems caused by earthquakes around the world. The results represent an important element in the process of seismic mitigation of lifelines risks. Use of these fragility data will allow water system owners to estimate the vulnerability of their systems and make informed decisions to mitigate risks.

Seismic Fragility Formulations for Water Systems:
Part 1 - Guideline (104 pages)


Seismic Fragility Formulations for Water Systems:
Part 2 - Appendices (239 pages

I hope this may help you

Leonard@thill.biz

http://www.thill.biz

 

[jfduroch]

I suggest that you have a look at the recent OMAE (Offshore MEchanics and Actic Engineering Conference) 2002-2003 and OTC 2002-2003 (offshore technology conference). I remember that Solt Offshore have carried out a research program on the thermal preformance on buried pipeline and reported some result in a publication in one of those conference.