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External Fire Case Relief Rate Requirement Based On Steam For Hc Servi


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#1 shantanu.ghag

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Posted 06 October 2019 - 07:21 AM

Dear all, 

 

I come across the PRV Specification sheet installed on Fuel Gas Drum-HC service. (please find attached sheet)

 

It has been observed that fire case scenario does not considers HC as fluid but steam, while other scenario considers drum fluid as HC.

 

I have gone through API 520/521 for this but does not find any such consideration.

 

I am curious about why steam is used to find relief requirement of this valve, could anyone please explain why it so if it is general engg. practice?

 

Thanks in advance.

 

Shantanu Ghag.   

Attached Files


Edited by shantanu.ghag, 06 October 2019 - 09:47 AM.


#2 PhilippM

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Posted 06 October 2019 - 09:32 AM

You did not attach the specification sheet.

 

What liquids can be expected during normal or upset operation in the drum? If two separate liquid phases might be present, some client standards require you to calculate the orifice area for both phases with the same wetted area, and then use the one with the larger resulting orifice area.



#3 shantanu.ghag

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Posted 06 October 2019 - 09:49 AM

You did not attach the specification sheet.

 

What liquids can be expected during normal or upset operation in the drum? If two separate liquid phases might be present, some client standards require you to calculate the orifice area for both phases with the same wetted area, and then use the one with the larger resulting orifice area.

my apology Phillip, missed earlier. Please find attached. 



#4 Bobby Strain

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Posted 07 October 2019 - 06:30 PM

You should have noticed the capacity provided. There is certainly no need to even question adequacy for fire relief. Whatever the fluid. You need to learn to spend your time and energy on things of importance.

 

Bobby



#5 Pilesar

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Posted 07 October 2019 - 11:15 PM

Steam used in the external fire case gives a conservative required relief area and is easily calculated. The fire case is no where near controlling the required size, and this is all the documentation needed for fire case calcs. I suggest you go through some relief sizing calcs yourself to verify whether the fire case with hydrocarbon or the fire case with steam would require a larger relief area.



#6 shantanu.ghag

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Posted 09 October 2019 - 02:09 AM

You should have noticed the capacity provided. There is certainly no need to even question adequacy for fire relief. Whatever the fluid. You need to learn to spend your time and energy on things of importance.

 

Bobby

thank you sir. your suggestions are well noted.



#7 shantanu.ghag

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Posted 09 October 2019 - 02:14 AM

Steam used in the external fire case gives a conservative required relief area and is easily calculated. The fire case is no where near controlling the required size, and this is all the documentation needed for fire case calcs. I suggest you go through some relief sizing calcs yourself to verify whether the fire case with hydrocarbon or the fire case with steam would require a larger relief area.

alright thanks. i will check.






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