7 replies to this topic

[farid.k]

What is the function of rupture disc at upstream of relief valve (inlet of relief valve)? Some of the standard say (API 521 clause 4.3.2.1), rupture disk (upstream of relief valve) to seal the system to meet emission standard, to provide corrosion protection for the valve and to reduce valve protection. How by having that can achieve all the statement above? I still can’t imagine. The other things, the rupture disk shall have pressure gauge and free vent to atmospheric. How can if the service is flammable/toxic to have open drain?  

[fallah]

farid.k,

 

In fact, a RD is normally installed upstream of  a PSV to avoid leakage of highly toxic or high cost materials, or to minimize corrosion or fouling of the PSV due to corrosive or high viscous fluids.

 

The space between PSV and upstream RD is so small when is to be vented to the atmosphere will result in no concern regarding safety or health issues...

[farid.k]

farid.k,
 
In fact, a RD is normally installed upstream of  a PSV to avoid leakage of highly toxic or high cost materials, or to minimize corrosion or fouling of the PSV due to corrosive or high viscous fluids.
 
The space between PSV and upstream RD is so small when is to be vented to the atmosphere will result in no concern regarding safety or health issues...

-How can by having the RD can avoid leakage? I mean here, is there any problem to have that relief valve to operate alone without RD? I still can't imagine how. If to minimize corrosion yes agreed since the fluid will not be contact with the valve.
-currently, the relief valve operate without RD. Is it I need to resize back current running relief valve after add the RD?

[fallah]

farid.k,

 

- A PSV alone may be a source of leakage of inventory especially at higher operating pressures and also especially when maximum operating pressure is too close to the PSV set pressure. By adding a RD at PSV upstream such leakage would be almost avoided due to inherently blinding nature of the RD. If the RD itself to be a source of leakage due to, let say, improper manufacturing it can be recognized quickly for subsequent substitution with proper one.

 

- Adding a RD at existing PSV upstream will mandate recalculation of PSV inlet line loss to check if is still within allowable range and also if can affect on PSV rated capacity...

Edited by fallah, 07 July 2014 - 05:36 AM.

[farid.k]

farid.k,
 
- A PSV alone may be a source of leakage of inventory especially at higher operating pressures and also especially when maximum operating pressure is too close to the PSV set pressure. By adding a RD at PSV upstream such leakage would be almost avoided due to inherently blinding nature of the RD. If the RD itself to be a source of leakage due to, let say, improper manufacturing it can be recognized quickly for subsequent substitution with proper one.
 
- Adding a RD at existing PSV upstream will mandate recalculation of PSV inlet line loss to check if is still within allowable range and also if can affect on PSV rated capacity...

Does it "leakage" here means psv pop up?

[fallah]

farid.k,

 

By "Leakage" i didn't mean psv pop up, but i did mean a situation such as "Simmer" in which there would be escape of inventory through the microscopic gap between the disc and seat and may be happen at the inlet static pressure lower than the set pressure before PSV opening...

[breizh]

Farid,

In addition to  what Fallah has explainred a document with drawing to visualize the combination RD and safety valve .

 

Hope this helps

 

Breizh

[farid.k]

Farid,

In addition to  what Fallah has explainred a document with drawing to visualize the combination RD and safety valve .

 

Hope this helps

 

Breizh

Breizh,

 

thanks so much for the good additional info.