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Non Slam Check Valve For Compressor


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#26 ogpprocessing

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Posted 09 May 2012 - 02:23 PM

Fallah,


If you check the post no.17 of me you will find that I have checked your attached document and I found it interesting because this document support the idea of blockage by check valve. This is a real concern regardless of the check valve type as mentioned by you (which in my view is an optimistic and not realistic assumption). That is why check valve installation is prohibited for flare lines. That is why pump minimum flow line take off point is from upstream of check valve. That is why check valve near compressor discharge nozzle is not allowed unless this is proved that there are enough safegaurds for compressor against blocked discharge. These are all valid references (you are looking for) based on previous project experiences which caused major damages to plant and equipment because of the lack of proper design or maybe because of optimistic assumptions like the one proposed by you!

#27 fallah

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Posted 09 May 2012 - 11:49 PM

'ogpprocessing', on 09 May 2012 - 7:33 PM, said:

Fallah,

If you check the post no.17 of me you will find that I have checked your attached document and I found it interesting because this document support the idea of blockage by check valve. This is a real concern regardless of the check valve type as mentioned by you (which in my view is an optimistic and not realistic assumption). That is why check valve installation is prohibited for flare lines. That is why pump minimum flow line take off point is from upstream of check valve. That is why check valve near compressor discharge nozzle is not allowed unless this is proved that there are enough safegaurds for compressor against blocked discharge. These are all valid references (you are looking for) based on previous project experiences which caused major damages to plant and equipment because of the lack of proper design or maybe because of optimistic assumptions like the one proposed by you!


ogpprocessing,

Seems you forgot my explanation in post 18 as response to post no. 17 of you, then i have to repeat here again as follows:


.....Anyway, we should seriously avoid confusing in our discussion. The main issue on which we are discussing is using the check valve in compressor discharge line not using it in PSV inlet/outlet lines. If you accurately read the page of document i did attach it refers to the point that using check valve in "process pressure relieving path" could be acceptable, and there is no contradiction with other point in this document mentioned that using check valve in PSV inlet/outlet lines isn't permissible. Obviously the first point addresses to process path and the second one to PSV inlet/outlet and flare lines.
In fact, in the cases the PSV's are located on process lines (such as compressor discharge line) the PSV inlet/outlet lines are parts of "pressure relieving path" and the remain is "process pressure relieving path"....



If you fail to distinguish the difference between "process pressure relieving path" and "safety pressure relieving path" you cannot understand what i said. I repeat the main points of the mine as per mentioned reference and other valid references as follows:
1- Check valve installation is strongly prohibited in "safety pressure relieving path" such as PSV inlet/outlet and flare lines.
2-Check valve installation, with having the conditions mentioned in that reference, in "process pressure relieving path" is acceptable.
3- In a single pump it is better to take off the minimum flow line upstream of the check valve especially because due to fit to fit installation of the check valve and discharge isolation valve, there would be no space between these two valves to take off the branch!
Nevertheless, in most two parallel pumps the common minimum flow line's take off point is from discharge header i.e. after pumps check valves.
4- In API 521, as best reference for credible overpressure scenarios in process area with having detail discussion regard to overpressure due to reverse flow from check valve, there isn't any reflected concern about the check valve blockage in normal flow direction.


Fallah

Edited by fallah, 09 May 2012 - 11:58 PM.


#28 ogpprocessing

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Posted 11 May 2012 - 02:10 PM

Quote


1- Check valve installation is strongly prohibited in "safety pressure relieving path" such as PSV inlet/outlet and flare lines.



Do you know why?


Quote


2-Check valve installation, with having the conditions mentioned in that reference, in "process pressure relieving path" is acceptable.



Refer to my previous post about optimistic assumptions at design and severe consequences studied during Hazop.

Quote

3- In a single pump it is better to take off the minimum flow line upstream of the check valve especially because due to fit to fit installation of the check valve and discharge isolation valve, there would be no space between these two valves to take off the branch!
Nevertheless, in most two parallel pumps the common minimum flow line's take off point is from discharge header i.e. after pumps check valves.



This is wrong design for parallel pump.

Quote


4- In API 521, as best reference for credible overpressure scenarios in process area with having detail discussion regard to overpressure due to reverse flow from check valve, there isn't any reflected concern about the check valve blockage in normal flow direction.



You should refer to blocked outlet section of API 521 and not check valve malfunction section. Otherwise we should expect API to have different parts for different types of valve such as ball, gate, globe, butterfly,.... !




#29 fallah

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Posted 13 May 2012 - 02:58 AM

ogpprocessing,

1- Because it could restrict the flow cross section such as any restriction in flow direction and this couldn't be accepted in "safety pressure relieving path".

2- They are realistic assumptions even somebody may wouldn't like to accept!

3- Eventually, it is an economical design based on good engineering practices!

4- You are refering me to blocked outlet section of API 521 for check valve blockage. Now we await you submit the statement from that section refering to possibility of check valve blockage as a general concern about all check valve types.


Bottom line is that you shouldn't try to generalize the check valve blockage as an universal credible scenario just based on some HAZOP meeting to which you have participated!

Fallah

Edited by fallah, 13 May 2012 - 03:05 AM.


#30 ogpprocessing

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Posted 13 May 2012 - 12:33 PM

'fallah', on 13 May 2012 - 08:08 AM, said:

ogpprocessing,

1- Because it could restrict the flow cross section such as any restriction in flow direction and this couldn't be accepted in "safety pressure relieving path".



Restriction on pressure relieving lines is not always a concern (for example RO downstream of BDV). The main concern is line blockage due to check valve malfunction.

Quote

2- They are realistic assumptions even somebody may wouldn't like to accept!



Good luck with your realistic assumptions even if this is against many years of experiences and safety precautions.

Quote

3- Eventually, it is an economical design based on good engineering practices!



Good luck with your economical design even if this can damage your pump!

Quote

4- You are refering me to blocked outlet section of API 521 for check valve blockage. Now we await you submit the statement from that section refering to possibility of check valve blockage as a general concern about all check valve types.

Bottom line is that you shouldn't try to generalize the check valve blockage as an universal credible scenario just based on some HAZOP meeting to which you have participated!

Fallah


What is mentioned at API 521 is any kind of source of blockage either this is valve or something else. This is a general concern.

#31 fallah

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Posted 14 May 2012 - 09:32 AM

ogpprocessing,

1-If restriction on pressure relieving lines isn't a concern, for example why the isolation valves in inlet/outlet lines of PSV's shall be full bore type?

2-They are realistic assumption because that book included such assumption is written based on many years of experiences!

3-Your response indicates that you are not familiar with BP, TOTAL,...design practices regarding minimum flow design in parallel pumps!

4-You did refer me to a section of API 521 and in response to my follow-up you havn't any specific address in hand.
Indeed, IMO the reason of that API 521 don't refer to check valve blockage as a source of blocked outlet (while has dedicated a section to overpressure due to reverse flow from it), is this point that it cannot be generalized and in most cases (depending on the valve type) there would be no concern regarding check valve as a source of blockage.
Surely you did note to the point that the title of section 4.3.4 of API 521 as a potential of overpressure is "check-valve leakage or failure", while this section just included overpressure due to reverse flow!

Fallah

Edited by fallah, 14 May 2012 - 09:36 AM.


#32 Poosticks

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Posted 01 December 2012 - 03:00 PM

Would you really need to take consideration of check valve malfunction? This would be two different malfunctions simultaneously occurring - we would usually not go down this path.




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