Pipeline in mining area

[wdudi]

Could anybody give me tip on where can I find any information about natural gas pipeline design, laying on mining area? How should I include existence of surface subsidences in strength calculation? How to protect such pipeline against damage?

 

[rconner]

I noticed there has not been one response to your post after several weeks. I do not profess to be an expert in such design of natural gas pipelines, but I wonder if installing the pipeline e.g. "on supports" (or piles etc.) in this area, perhaps also with some "redundancy" (e.g. in the way of heavier beam strength pipes and/or with more frequent axial spacing of supports?) might be one approach. If one or more supports e.g. were to succumb to a sinkhole, is it possible the line might still survive based on its beam strength and adjacent supports? [You might want to view some of the responses/linked references on the "seismic" thread that immediately precedes this thread.] There might also be some be some ball joint and/or specialty expansion devices (manufacturers) available for gas pipelines that might be used to provide for some local ground/line movement, perhaps also without unreasonably stressing the pipeline.

 

[1969grad]

As I recall the ASCE has done some work on pipelines in areas subject to earthquakes. The information (conference proceedings I think) may be as far back as the 1980s.

You indicate that the pipeline is to be laid in a mining area. Would the pipeline then be subject to the impact of explosives used in mining operations? If so then the considerations for an earthquake design might also apply.

 

[1969grad]

I just noticed the previous thread on pipelines crossing fault lines in this section which may provide some help.

 

[wdudi]

Thanks for help 1969grad. Since start of November I've found some intresting informations on the internet sites on it how to monitor and eventualy lower a pipeline while in service. Ii'll be more helpful for me to know how to preserve a pipeline on the design stage? I've made also a strength analysis in ABAQUS, but here is my problem. Obtained results varies from analytical solution. Why? I'm looking for answer. My natural gas pipeline will be buried and max prognosed soil horizontal strain is 6 mm/m. SMYS of pipe's material is 360 MPa. Explosives used in mininf area are not dangerous for my pipeline. More important are loads from soil subsidences.

 

[stanweld]

Advise contacting the Gas Research Institute or the AGA. I know they sponsored/directed work with regard to subsidence and heave in the 1970s and 1980s. You may also wish to contact Battelle Memorial Labs as well.

 

[vzeos]

Take a look at Design Guideline for Buried Steel Pipe at the attached site (scroll down).

http://www.americanlifelinesalliance.org/Products_new3.htm#BuriedPipe/PipeguideFinalPosted061705

[1].pdf

 

[rconner]

It could be the description "evidence of surface subsidences" is something maybe a little hard to design to. When I heard the term "subsidence" in a "mining" area, my mind perhaps overly raced to the worst seeming cases I could imagine, being a void under a pipe or sinkhole around a pipe, or perhaps also the effect at the edge of a large expanse of subsidence area where it joins ground/strata that does not subside at all (it would appear the latter could be sort of like a very slow moving earthquake "fault"). If one were to assume that subsidence were to proceed to rather extreme circumstances (e.g. a sinkhole), it appears that there are a lot of interesting pictures, examples etc. that come up when one does a google search e.g. with keywords like

http://www.google.com/search?hl=en&q=sinkhole+gas+pipe+failure&btnG=Google+Search

.
I happened to see yesterday reference to an apparently relatively new paper that could conceivably also be of interest available from

http://www.pubs.asce.org/

http://WWWdisplay.cgi?0500727

entitled, "Failure Mechanisms in Pipelines Bridging a Void" (I noticed GRI, hinted by stanweld appears somehow referenced in this report).