High end vent insulation 1

[simplemath]

16" Cryogenic process line branch out 2" flange ball valve with blind serveing as an high point vent. The process line has insulation. I am asking whether the vent valve should be insulated or not.

IMHP, it is a dead end thus as long as the valve located away enough to see cold temperature , it should not be insulated. My current design is valve center line 28" above from the process line top of insulation. The branch line insulation will extend 24" above from the process line top of insulation.

Please advise me if my design fits the general practice.

 

[BigInch]

Will the uninsulated vent line be a source of heat sufficient to boil any product contained in the vent line and bubble it back into the process line?

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[simplemath]

Thanks, Biginch.

The product is LNG. Yes, just like you said, LNG will first boil off as NG and occupy the vent line which serves as heat barrier and prevents LNG flow into vent line.
It shares same principal as cryogenic valve that has extended bonnet (18in).

What do you mean by “bubble it back into the process line”?

Thanks.

 

[BigInch]

My only thought was, if it turns to vapor there, and with continued heat input, will it eventually fill that vent line a little too much and flow some into the liquid below? Probably wouldn't last long as a two phase anyway.

No personnel protection insulation required above 24"?

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"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

 

[simplemath]

Correct me if wrong.

Gas that filled in the branch pipe serves as good insulation. Gas has very low thermal conductivity and 28" static gas "insulation" will be enough or in my opinion much better than adjacent solid insulation(CS 9"). So evaporation due to the uninsulated vent line will not be worse than where insulation is.

Pipe has BOG vent line and PRV that could keep pressure balance.

Thanks.