8 replies to this topic

[mido]

we have many cases in our plants of installation indirect heaters in trunk lines and at oil processing plants inlet. the supplier of indirect heaters sometimes supplied it with thermal expansion safety relief . i want to know when this safety relief is mandatory to install and when it is not mandatory because some other suppliers supplied indirect heaters without this PSV. and what the reference for install or not install that PSV?

thanks very much

[fallah]

Mido:

 

In general when the fluid being heated is blocked in and the heating fluid is still flowing...

[Chemitofreak]

Liquid thermal expansion over pressure can occur, when a system that contains a liquid is blocked in and the heat is gained from the environment (solar) or from the process. This causes the liquid to heat up and expand. If the liquid is confined, this expansion can result in over pressure.

 

One has to take into consideration the amount of liquid that can be trapped in between two valves for specifying the thermal relief valve.

Edited by Chemitofreak, 30 November 2018 - 03:45 AM.

[mido]

Thanks for reply but my concern is about the need of safety relief if if the indirect heater have only manual isolation valves and not have automated shutdowns ...... can we remove this psv and control this hazard by administrative control that (in case of heater isolated to drain it). as this project is upgrade to existing system and to connect PSV to flare is not feasible.  

[fallah]

Thanks for reply but my concern is about the need of safety relief if if the indirect heater have only manual isolation valves and not have automated shutdowns ...... can we remove this psv and control this hazard by administrative control that (in case of heater isolated to drain it). as this project is upgrade to existing system and to connect PSV to flare is not feasible.  

 

In general, administrative control cannot be used instead of a PSV for overpressure relief...

[asantosa]

Hello, interesting this topic reagrding on the volumne of the fluis that it is blocked; but actually, I´ve never found volume criteria of the fluid  that is trapped? FOoinstance, if the volume is higher than 50 liters, do I hace to install a TRV, no matter the classification of the fluid is ? ( inflamable, or toxic, etc ). This criteria shall be applied in interconnecting lines outside of batttery limit  or tanckage areas, but actually I do not know the volume or pipe lenght to be applied...Does anyone has heard about criteria for this? thanks

[Chemitofreak]

@ Asantosa:

 

It can vary from company to company. In our company it is considered as 500 Liters

[breizh]

@ Asantosa,

 

Consider the link underneath.

 

https://www.eng-tips....cfm?qid=171158

 

Breizh 

[samayaraj]

@ Asantosa,

 

Consider the link underneath.

 

https://www.eng-tips....cfm?qid=171158

 

Breizh 

 

Great thread! Mr. Art has given excellent point in choosing ball/ plug valve with self venting hole.