Jump to content



Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

Vertical Tank Selection

New Blog Entry

Low Flow in Pipes- posted in Ankur's blog

Psv Bypass Line Distance Between Isolation Valve And Globe Valve

psv bypass line

This topic has been archived. This means that you cannot reply to this topic.
6 replies to this topic
Share this topic:
| More

#1 chem2013

chem2013

    Veteran Member

  • Members
  • 36 posts

Posted 12 January 2017 - 10:21 AM

Hi All,

 

Manual depressurization line around PSV has an isolation valve [ball valve] and a globe valve downstream of this. Shell DEP suggests that minimum distance between this two valve to be minimum 600 mm.

 

Reason is not clearly mentioned for this. It looks during manual depressurization through this globe valve [ especially for high pressure system] downstream of this valve will see lower temperature. This cold temperature will cool down metallic pipe and via conduction cold temperature will flow backward and manual operation of isolation valve will be problematic due to frosting/freezing of air.

 

In another scenario, if we need to install a RO in addition to globe valve then what would be the best location of this RO ?

 

(1)downstream of globe valve as distance between globe valve and upstream isolation valve will be 600 mm minimum.

 

(2)RO just after ball type isolation valve. Distance between ball and globe valve will be 600 mm. 

 

Please share your opinion.

 

Regards,

 



#2 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,930 posts

Posted 12 January 2017 - 12:05 PM

chem2013,

The reason of considering 600 mm distance is clear...
When there is a globe valve in your mentioned configuration which plays the role of a variable RO, considering an additional RO isn't so reasonable...

#3 chem2013

chem2013

    Veteran Member

  • Members
  • 36 posts

Posted 13 January 2017 - 10:52 AM

Hi Fallah,

 

Thanks for your reply. RO is provided to avoid overpressurization and AIV [acoustic induced vibration] in low pressure rated line. Question is if we provide RO and globe valve on PSV bypass line , then 600 mm distance should we consider from RO [if RO installed between isolation valve and globe valve] or from globe valve ? 

 

Regards,

Chem2013



#4 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,930 posts

Posted 13 January 2017 - 01:53 PM

Chem2013,

Please let's know the source through which the requirement of RO is justified...

#5 chem2013

chem2013

    Veteran Member

  • Members
  • 36 posts

Posted 28 January 2017 - 04:13 AM

Hi Fallah,

 

RO was proposed to prevent overpressure and AIV(acoustic induced vibrartion) in downstream piping. A study was conducted to justify its requirement.

 

But it looks that if we provide RO on PSV bypass line then manual globe valve is unnecessary in the same path. Distance requirement of 1000mm / 600 mm between RO and first upstream isolation valve.

 

Regards,

Samiran



#6 SPC

SPC

    Junior Member

  • Members
  • 28 posts

Posted 09 February 2017 - 10:26 AM

Chem2013,

 

      As you said " RO is provided to avoid overpressurization and AIV [acoustic induced vibration] in low pressure rated line."

 

Please see below purpose of RO:

 

Restriction orifice (RO) is mainly used to achieve controlled or restricted flow of process medium. The orifice offers a restriction to the process flow and the pressure head drops from the upstream to the downstream. The permanent pressure loss by the device is the intended pressure drop for which it is sized. The area of the orifice determines the rate of flow at the outlet of a given process fluid for the specified pressure and temperature.

 

Following are application examples for RO :

(i) Restriction Orifice (RO) at the downstream of blowdown valves.

 (ii) Restriction Orifice (RO) in pump recirculation line.

 (iii) Restriction Orifice (RO) to restrict gas blow-by.

 (iv) Restriction Orifice (RO) to check excess flow.

 (v) Restriction Orifice (RO) for controlled pressurization.

 

you can go through google & find more information

 

Regards,

SPC



#7 chem2013

chem2013

    Veteran Member

  • Members
  • 36 posts

Posted 12 February 2017 - 08:38 AM

SCP,
Your reply is not to the point.
Regards




Similar Topics