In the picture at the top of this article it shows a long pipeline.
At regular intervals, either side of the pipe are a pair of ‘sticky up thingies’ [technical term].
What are these dodads?
About 1/3rd of the way down this page is a picture of a pipeline with the following comment:
Those tubes with fins on top of the pipeline supports, are heat exchangers. They refrigerate the poles underground to prevent the frozen tundra from defrosting.
Here’s another link
The 2nd link is not completely true: “Since ammonia, the working fluid in the heat pipes, has a freezing point lower than the permafrost, the heat pipe works throughout the year, even during the coldest winter nights.”
The heat pipes only “work” when the air temperature is lower than the permafrost. The ambient air cools the heat pipes; the very-cold ammonia circulates to the permafrost and cools the permafrost.
When the ambient air is warmer than the permafrost (e.g. April to October), the warmer ammonia stays on top without circulating.
In areas where the permafrost has melted, generally the ground will subside a number of feet and will become very uneven and hummocky. Obviously, this would not bode well for the integrity of the pipe. A spill or at the very least a very expensive restructuring would be likely.
In the parts of the Arctic where the pipeline has been built, it’s both a pristine environment and usually very remote. It could be awhile before crews could be on scene to assess any spill and begin clean-up efforts. Keeping the permafrost ‘permanent’ is key to the pipeline’s utilization.
Thank you guys. Ignorance fought.
Just wanted to add that the heat exchangers were developed and built by my pre-retirement employer, McDonnell-Douglas (now Boeing).