How to calculate pipe temperature during relief?

[bmp28]

Hello All,

I'm trying to estimate the time taken to heat up the releif valve discharge pipe to the relief temperature from the upstream PSV.

The pipe in question is a 12" uninsulated 150# CS pipe with relief temperature of 372 degC. The ambient temperature is 30degC and and wind velocity is 10 m/s. Please would you direct me to the right formulas to use or a source where I can find more information.

 

[MortenA]

You have to establish a heat balance - if you want to do it in details.

You should take a look at the article from Hydrocarbon Processing july 2004: Material selection for low temperature applications ( S. Kumar et. al.) They describe how to estimate wall temp and select materials.

Best regards

Morten

 

[wfn217]

dT/dt =h*A*(T-Tair) + epsilon*sigma*A*(T^4-Tair^4). Integrate.

 

[wfn217]

The right hand side should be divided by the mass times the heat capacity.

 

[JoeTank]

MortenA
Do you have a copy of the article cited? if not, do you know who might have it available on a website?

Joe Tank

 

[reena1957]

Dear JoeTank,
I have seen the original article and you better be prepared for some good math and ExCEL with VB. The article is for cold cryogenic gas discharge whreras your case is for hot gas discharge( it appears). It also refers to API 579. The author can be contacted at k.sunil@telstra.com
Bbest wishes

 

[roker]

hello,

see thread 124-98845 and the Safety relief valve engineering.

regards,
roker

 

[MortenA]

The math would be the same disregarding the fact that this is a hot gas. The material selection guide thats a nice frationc of the article will however be fairly useless

About a copy: Why dont you try a local (technical) library if you dont have the magazine?

I dont have a "swap place" set up already...

Will try and see what i can do.

Best regards

Morten