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223 comments on Open Thread: On punishing ExxonMobil

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Engineer-Poet on April 17, 2006 - 11:36pm Permalink | Subthread | Parent | Comments top
I distinctly recall specific design features to avoid this, such as one-way heat pipes built into support piers which boil ammonia in the depths and transfer heat to finned heat sinks during the winter cold, but pool the ammonia in the bottom whenever the top is warmer than the bottom.  This tends to keep the piers colder than the average permafrost around them.

I don't put much credence in your scenario.  Warming trends putting the system beyond its design parameters is all too credible, however.

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earldaily on April 18, 2006 - 2:59am Permalink | Subthread | Parent | Comments top
I don't know how much credence I put into my scenario ether, it was just something I heard. but I can't even begin to wrap my head around yours.
one way heat pipes? finned heat sinks? some sort of captured ammonia system? we're talking half a million/ footing here easy.how many feet of pipeline/footing?technicaly I'm in so far over my head I'll just have to guess at one per 450'? is that close? do you or anyone else have an elevation drawing of these foot prints? my little contactor mind is putting together a picture here and I'm begining to see why anyone would be hesitant to build a gas pipeline from russia to china.
thanks for the reply
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dinaz on April 18, 2006 - 11:29am Permalink | Subthread | Parent | Comments top
The most conventional method for dealing with "frost heaving" that one would encounter in ground that freezes and thaws annually is to build footings as deep as necessary to avoid this process. Cold climate construction almost always involves building on footings or piles that are below the frost line, the point of deth where annual soil freeze/thaw does not occur. It is possible this elaborate method is used to stabilise some pipeline footings but I'd bet that the great majority of pipeline footings are simply piles with footings set deep enough to be on bedrock or permafrost. I'd guess that costs for footings don't approach those for pipe and welding labour - especially these days. (anyone know better?) The latter presents major problems for pipeline stability if annual soil thaw begins to move deeper and deeper. These piles will need to be rebuilt even deeper (on bedrock or deeper frost). I can't imagine how expensive this could be. Then again, what is the cost of not being able to deliver fuel?
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Engineer-Poet on April 18, 2006 - 12:43pm Permalink | Subthread | Parent | Comments top
one way heat pipes? finned heat sinks? some sort of captured ammonia system? we're talking half a million/ footing here easy.

Actually, you're talking about a welded steel tube through the concrete pier (could be used as part of the reinforcing steel) which terminates in some sheet-metal fins, which might be steel or might be aluminum.  The tube has maybe a pound or two of anhydrous ammmonia in it (costs about 25¢/lb even at today's ridiculous prices), or you could use propane.  The "one way" effect is achieved by simple physics:  liquid pools at the bottom, while vapor condensing at the top runs down the sides (to make it run both ways you need a wick to get capillary action).  The finned heat sink at the top could be more steel (but requires rustproofing) or an aluminum extrusion (much less money in fabrication but pricier material).

You're talking more like a hundred bucks a footing, or a small multiple thereof.

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earldaily on April 18, 2006 - 1:43pm Permalink | Subthread | Parent | Comments top
ok I can visualize that, thanks
as far as the price I've poured alot of foundations in my time time and there expensive. with a better mental picture  I can see 1/2 a mill is way over the top. but I'm gonna charge $1000 a day just to show up. getting concrete to the site. well anyway when they talk about building these things they're tossing the words "billions of dollars" around like it doesn't mean anything. yet another thing I can't wrap my head around.
thanks again
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fallout on April 18, 2006 - 3:34pm Permalink | Subthread | Parent | Comments top
Half of the 800 mile pipeline is above the ground. This was done to keep the warm oil (approximately 140 degrees Fahrenheit) from melting the frozen ground (known as permafrost). The pipeline is held up off the ground on a small platform supported by two 16-inch diameter vertical support pipes that are buried between 15 and 60 feet into the frozen ground.
These vertical support pipes are cooled by refrigerant coils which help to keep them from transmitting heat into the ground and consequently melting the frozen ground which supports the pipeline. These refrigerators, usually two and sometimes three in each vertical support, are completely passive; that is, they work automatically, requiring no power, whenever the surrounding air temperature is lower than the ground temperature.
"Specially designed vertical supports were placed in drilled holes or driven into the ground. In warm permafrost and other areas where heat might cause undesirable thawing, the supports contain two each, 2-inch pipes called "heat pipes," containing anhydrous ammonia, which vaporizes below ground, rises and condenses above-ground, removing ground heat whenever the ground temperature exceeds the temperature of the air. Heat is transferred through the walls of the heat pipes to aluminum radiators atop the pipes."

http://www.alyeska-pipe.com/Pipelinefacts/PipelineEngineering.html

Keep in mind that the pipeline was built with the ultimate in expediency in mind. The Aleyska Pipeline Consortium was more than willing to pay extra and sacrifice long term durability in exchange for immediate profits.  It had already been delayed for over 4 years by legal challenges, and the estimated 600 million barrels a day it would carry would more than make up for any shortcuts taken.  The fact that it has lasted this long is a testiment to luck and good quality construction on the part of those who braved the elements to assemble it.

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earldaily on April 18, 2006 - 5:17pm Permalink | Subthread | Parent | Comments top
this has to be the best site on the internet
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223 comments on Open Thread: On punishing ExxonMobil

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