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[chem55]

Hello All,

 

In my application as per attached picture, I have one compressor which will not be in use and another compressor which will be working when plant in operation. As per current design, the compressor which will not be used has two check valves at the discharge line of the compressor A, and at the upstream of check valves it has PSV set at 100 psig. Another compressor B will be in operation and when plant will start it will have 600 psig discharge pressure. 

 

As per sketch the compressor A (which will not be in use) doesn't have any block valve at the downstream of check valves.

 

My concern is back flow as my understanding is check valve is not fully leak proofed. As the pressure of orange highlighted line will be 600 psig, the gas will go through the check valve and it will pressurize the line and it will pass through PSV located upstream of check valves.

 

I am thinking to install block valve at the downstream of check valve which will be normally closed. Please advise.