Nitrogen Testing at Temperature

[Bill2022]

Hi looking for some input on a topic, I have performed a lot of pressure testing over the years and have recently moved into the the realms of 20,000 PSI N2 Gas Testing at temperature's of +160 Degrees C and -18 Degrees C of Subsea Products.

My question:
(1) what temperature would you expect to see at the Vent Point at High and Low temperature.
(2) Will Speed of vent effect Hoses, Tubing or Check valve openings in the system (I have always been told a controlled bleed down, however there are discussions internally with engineering that the speed of vent down is immaterial)

 

[LittleInch]

What sort of volume are you talking about?

You're not testing at those temperatures are you?

Speed of vent affects erosion of the items you list and the noise of the vent down. You will hit sonic velocity somewhere at those pressures unless you run it through a silencer.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EdStainless]

So when you vent the throttling of the N2 will result in cooling, a lot of cooling.
When testing hot you will start venting at 160C, and it will cool.
I didn't run your exact numbers but off hand I would estimate a 150-200K temperature drop.
You are going to have some very low temps when you start at -18C.
This will take equipment that will operate at cryogenic temperatures.
The speed will have an impact, faster venting will cool faster.
Typically with high pressures you would capture much of the gas at high P to reuse without having to do as much compression.

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P.E. Metallurgy, consulting work welcomed

 

[Bill2022]

Hi
Yes we are at these temperature's as required by code, typically we perform these tests on 10K and 15K products and have volume reducers inside to reduce the gas volume in this case its a 5" Bore with 4.800" Volume fillers. pressure is being vented via a 3/8" HP Needle Valve so the opening is small. Part of the test is to evaluate the Elastomeric Seals as well as the metal work, very common that the Elastomeric crap out and you have to select an alternative compound and keep repeating until you succeed.

 

[Bill2022]

Hi, my concern is the cooling when we vent, as the tool is sat at those temperatures for days so the N2 will also saturate elastermerics and hoses in the system, there is little heat transfer observed during the testing and i'm unsure what the Gas would be doing at these temperatures and pressure, then suddenly released to atmosphere.