Depth of Frost GRP Pipe

Not from that reason. But something is improperly stated if the environmental temperature is "max -40°C".

I'd be surprised if it is -40C max 3 or 4 meters underground even anywhere on Antarctica.

Could be BIG problem with cold embrittlement and cracking depending on what you mean by, "air will transfer from within pipes" and the pressure and operating conditions.

What we have here, is failure to communicate.

You MUST CONSULT WITH THE CUSTOMER AND GET OPERATING CONDITIONS FROM THEM.

This project is doomed to fail.

there is dirty air at the room. this air will transfer with grp pipes by aspirator.

Thus far in the thread, nothing has been described adequately. Please give comprehensive details.

before i have to wright, my english may not be sufficient.therefore sorry. this project in mongolia. this is treatment plant. there is dirty air like sevage air at the room. customer will take air by ventilator. air temperature 25ºC. pipes will be glass reinforced pipe. but he doesnt say that diameter. pipes will be buried below 3-4 meter underground. outside temperature - 40ºC. i have only this detais..

thank you to all

Yes if it's being buried in a permafrost layer. The 3 to 4 meter depth is still in the active layer. It will be effected by the outside temperature. Just have to find a place where the average outside temperature is below -40°C. Not too many places that fits.

I do see another problem thou. As you are concerned about temperature. Sound like the customer may be using the pipe as ventilation. How about condensation freezing up. Won't take -40C for that to happen. May after a time clog the pipe.

i dont know pipe buried in permafrost layer. yes customer will use ventilator. dirty air temperature 25 ºC. i dont think so clog the pipe. i am thinking is there any table depth of frost regarding the outside temperature.

What is "GRP"? I am assuming it is something like "G.... reinforced plastic"....? garbage? green? glass? glunobtainium?

Anyway, are you sure you haven't mis-read the spec? If the pipe is containing air, it might be compressed air, dried to a -40C dewpoint? This is a pretty common spec for compressed air but it does not mean the air is very cold. It is a measure of the water content of the air.

If this is the case, you need to watch the permeability of the pipe because there will be a tremendous gradient across the pipe between the sahara-dry conditions inside the pipe and the relatively wet ambient conditions. This will guarantee water will migrate into the pipe and destroy the air dewpoint.

Jon.

GRP is glass reinforced pipe.pipe is containing air but not compressed.

Is "sevage air" supposed to be "sewage air"? If the air is not VERY dry there will be moisture. Moisture at those temps will freeze and in a short while it will clog. But if you are "producing the pipe", it sounds like someone else would be taking that into consideration.

I don't know how you could be "producing the pipe", without knowing the diameter, so I am very confused.

In Canada, the worlds second coldest capital (after Ulan Bator) the pipes are buried at LEAST four feet. Now, this is really important....The problem is not frozen pipes but the movement of blocks of frozen ground around and above the pipes. So if you have any doubts, dig your trench a couple of feet deeper!

Mongolia is not a nice place to dig. I don't think there is permafrost under the cities, but there is plenty of it north of the capital. If you are digging in permafrost...you have to do it with layered pipes. That is, one pipe inside the another.

Regards. It is a difficult job to plan out.

thank you to all everybody.