Separated layers of ice over a pipe

Note the arrows showing the layers.

Note the arrows showing the layers.

I want to know that why there are different layers of ice over a pipe carrying a cryogenic fluid, each layer separated with clear marks / lines? What do these layers signify?

One thought on “Separated layers of ice over a pipe

  1. Answer prior to receiving photo:
    Based on the explanation of the different layers I assume the cryogenic pipe is operating outside and not in a building. If this is the case, there is the consideration the pipe is exposed to the sun. I could only assume this is the case. The sun will heat the outer layer and cause it to become warmer and come close to melting on the outer surface, changing the structure of the ice. At night it will cool down again and solidify the near water substance. The ice was originally formed by collecting individual molecules from the air that solidified differently than if water is poured on the cold surface. This may be the reason for layering. There is also the consideration if the cryogenic fluid is used intermittently causing the line to warm and cool based on the cryogenic fluid use. Normally cryogenic lines are insulated using vacuum jacketed pipe or some type of mechanical insulation. In most cases the pipeline is not designed for large amounts of ice buildup. This could be dangerous and cause the pipe to become overstressed and possibly break. Agreed ice can be considered an insulator with a large buildup, but is not very efficient and operating costs increase.

    Further comment after receiving photo:
    It is very interesting to see the layers about the same thickness. I would assume the outer layer to be not as thick as the inner layers based on thermal conductivity through the ice. There are two considerations regarding the ice. First, what is the relative humidity in the area where the pipe is located? And second, what is the cryogenic fluid running through the pipe? If the cryogenic fluid is liquid nitrogen it will be condensing some oxygen as well as water vapor. If it is LNG it will only condense water vapor. Other item that may have an effect is the ambient temperature at the location over a 24 hour period?

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