Pipe Freezing Time: 150NB Steel Pipe in -15C

In summary, based on the given parameters of a 150NB Stainless Steel pipe lagged with 50mm thick rockwool insulation, and a design parameter of 5 consecutive days at -15C with static flow, it is likely that trace heating will be required. The working temperature of the potable water is 5C and the pipe runs 1.5m horizontal with a 2.5m vertical climb feeding a storage tank. With the given insulation, it is estimated that freeze conditions will occur in approximately 9-10 hours, taking into account stagnant water. However, if the water is constantly flowing, the insulation should be sufficient.
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I am trying to ascertain if a 150NB Stainless Steel pipe lagged with 50mm thick insulation would also require to be trace heated. The insulation used is rockwool. The parameters are that the pipe must not freeze solid given 5 straight days of -15 C with static flow. Wind chill is negligible. The pipe contains potable water. Any information would be greatly appreciated.
 
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  • #2
What's the maintenance temp of the potable? The length of the line?

At first glance, though, I'd say you'll have to heat trace that line. If your design parameter is multiple consecutive days at or around -15 C, then I'd say your insulation is not going to be sufficient.

References for you to look at:
Chromalox 1 (by Proheat Inc.)
Chromalox 2
 
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  • #3
Cheers Travis. Appologies for the lack of detail. The working temperature is 5 C and the pipe runs 1.5m horizontal with a 2.5 m vertical climb feeding a storage tank. I similarly suspect it may require trace heating but do think it is borderline.
 
  • #4
oh, that's a short run of pipe. Are you not worried about the storage tank? Or is that heated?

Either way, with 50 mm rockwool insulation, you're looking at a timeline of hours at that temp, not days. The calcs in the reference assume a few things, but they are fairly good estimates. There's no way you'll get 5 days of -15C temps out of that. More like half a day, if that.

A back-of-the-envelope calc indicates that you'll likely have freeze conditions in ~9-10 hours, probably a bit longer considering these numbers are factored. That's with stagnant water. If it's constantly running, the insulation is fine.
 

1. How long does it take for a 150NB steel pipe to freeze in -15°C?

The freezing time of a 150NB steel pipe in -15°C will depend on several factors such as the length and thickness of the pipe, the temperature of the surrounding environment, and the type of insulation. However, on average, it can take anywhere from 30 minutes to 2 hours for the pipe to freeze completely.

2. Why does a steel pipe freeze faster in -15°C compared to other materials?

Steel pipes are excellent conductors of heat, meaning they can easily transfer heat to their surroundings. In -15°C, the steel pipe will rapidly lose its heat to the colder environment, causing it to freeze faster compared to other materials with lower thermal conductivity.

3. Can pipe freezing damage the steel pipe?

Yes, pipe freezing can potentially damage the steel pipe. When water inside the pipe freezes, it expands, creating pressure within the pipe. This pressure can cause the pipe to crack or burst, leading to costly repairs or replacements.

4. How can pipe freezing be prevented in -15°C?

To prevent pipe freezing in -15°C, it is essential to properly insulate the pipes. Insulation can help slow down the transfer of heat from the pipes to the colder environment, reducing the chances of freezing. Additionally, keeping the pipes in heated or well-insulated areas can also prevent freezing.

5. Is there a specific type of insulation that is best for preventing pipe freezing in -15°C?

There is no one specific type of insulation that is best for preventing pipe freezing in -15°C. However, some commonly used insulation materials for pipes include foam, fiberglass, and mineral wool. It is essential to choose an appropriate insulation type based on the specific needs and conditions of the pipes.

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