5 replies to this topic

[kpavan]

Hi all,

Some of the safety valves of my plant are sized on the basis of JIS (Japanese Industries Standard) code. I would like to calculate the adequacy of a safety valve on a pressure vessel for external fire case. I searched for it on internet and even in the forum but could't get the code. Need help in getting the code or just the formula that can be used to calculate the same.

Any help regarding this is appreciable.

Regards.

[fallah]

Hi all,

Some of the safety valves of my plant are sized on the basis of JIS (Japanese Industries Standard) code. I would like to calculate the adequacy of a safety valve on a pressure vessel for external fire case. I searched for it on internet and even in the forum but could't get the code. Need help in getting the code or just the formula that can be used to calculate the same.

Any help regarding this is appreciable.

Regards.

Size the PSV as per API 520 and compare the result with the in hand size.

[kpavan]

Dear Fallah.

Thanks for the reply,
Calculated the case as per API-520... but getting the size of the PSV as per API-520 is 16.07 cm2 (which is "L") where as installed PSV size is 5.065 cm2 (which is "H") as per JIS standard.
So there is a huge difference in comparision to the installed PSV and calculated one.
Any further help in this matter is appreciable.

[fallah]

Dear Fallah.

Thanks for the reply,
Calculated the case as per API-520... but getting the size of the PSV as per API-520 is 16.07 cm2 (which is "L") where as installed PSV size is 5.065 cm2 (which is "H") as per JIS standard.
So there is a huge difference in comparision to the installed PSV and calculated one.
Any further help in this matter is appreciable.

Dear Kpavan,

As far as i know the actual size of "L" type would be 18.40 cm2.

Anyway,have you compared the relief load for fire case between the values obtained from API 521 and JIS standard?
The difference between sizes may be due to difference between calculated relief loads.

Regards

[djack77494]

kpavan.
If you're implying that you can't find the formula used by the code, I find that very hard to believe. If true and if you want to or are compelled to design to JIS code, than you will have to buy the applicable codes. If you can provide any more information on how the two calculations differ, we may be able to provide additional help. If you can, look at flow rates, heat absorbed, exposed area, and other more basic information until you root out the discrepancies.

Edited by djack77494, 08 September 2010 - 05:12 PM.

[kpavan]

Thanks for your replies,

Dear Fallah.

Thanks for the reply,
Calculated the case as per API-520... but getting the size of the PSV as per API-520 is 16.07 cm2 (which is "L") where as installed PSV size is 5.065 cm2 (which is "H") as per JIS standard.
So there is a huge difference in comparision to the installed PSV and calculated one.
Any further help in this matter is appreciable.

Dear Kpavan,

As far as i know the actual size of "L" type would be 18.40 cm2.

Anyway,have you compared the relief load for fire case between the values obtained from API 521 and JIS standard?
The difference between sizes may be due to difference between calculated relief loads.

Regards

Dear Fallah,

Seems there was some confusion...
Area calcuated as per API-521 is 16.07 cm2.. and this is less than 18.40 cm2 which is orifice 'L'. So I said i am getting bigger orifice size as per calcultions which is L. Here I didn't mean to say 16.07 cm2 is of L size.

kpavan.
If you're implying that you can't find the formula used by the code, I find that very hard to believe. If true and if you want to or are compelled to design to JIS code, than you will have to buy the applicable codes. If you can provide any more information on how the two calculations differ, we may be able to provide additional help. If you can, look at flow rates, heat absorbed, exposed area, and other more basic information until you root out the discrepancies.

Dear Djack,
The main thing for writing this post is to get atleast the formula as per JIS standard, as I know I have to check only fire case and for that have to buy a standard form JIS and at present we (our company) are not having JIS standards. As I understood getting the formula is difficult, so we are forwarding our problem to Hitachi who is PSV vendor to our plant.

Looking forward for more comments/help from you.

Thanks and Regards,
Pavan