3 replies to this topic

[Engineer87]

Hi Members,

 

Can any body explain me what are CSO/CSC valves? and their utilization in Chemical Process?

 

Regards,

 

[fallah]

Engineer87,

 

Use the search option of this site and you will find a lot of technical matters about the application/utilization of CSO/CSC valves...

[TS1979]

CSO valve - the valve is locked open. Without lock key, the valve cannot be closed. example is the isolation valve upstream/downstream of a PSV.

 

CSC valve - the valve is locked close. Without lock key, the valve cannot be opened. Example is the PSV bypass line. The valve on the PSV bypass line must be closed all the time except that the PSV is removed for emergency service.

[paulhorth]

TS1979,

 

CSO and CSC are NOT the same means of restriction as Locked Open and Locked Closed. Locked valves are shown as LO and LC on PIDs and use either a padlock and chain or a proprietary valve lock.

CSO stands for Car Sealed Open. The Car Seal is nothing more than a wire loop with a lead seal across its ends, through the valve wheel or lever. It does not require a key to operate, just a wire cutter, so it is not as secure as a genuine lock.

 

Both a Locked valve and a Car Sealed valve "should" require a written permit to operate, and thus act as safeguards against mistaken operation, but it is easier to take an unauthorised shortcut with a car seal.

Having said that, I have seen on site the startup team applying bolt cutters to locks as a routine, thus subverting the design intent that I as process engineer (and the HAZOP reviews) have put in to these systems.

 

Paul