27 replies to this topic

[J_Leo]

Bobby,

 

Thank you. I cannot publish any detailed documents here because it is against company policy.

 

Regards,

Leo

[J_Leo]

ChemEng01,

 

Yes, the normal upstream pressure of the TV is 50 psig. As in the previous response to S J, TV fail open is considered, otherwise there is no relief.

 

Thank you,

 

Leo

[S J]

J_Leo

 

It's definite that you need to consider both fail open if it's from HAZOP recommendation.

When I performed project with ExxonMobil, even though they agreed that it was double jeopardy, they wanted to consider the scenario.

When you calcutate fail open flowrate, you may need to use vendor calculation program or receive fail open flowrate at PSV set pressure or overpressure. In my experience, flowrate could change much as per vendor characteristic curve.

And administrative control for bypass is not agreed by client or someone has authority, you also need to consider both fail open of control valve and bypass. But , in this case, flowrate will be limited by PCV as you mentioned.

Anyway, thank you for sharing your experience.