Difference between control valve TSO and CSC
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I would like to ask the experienced colleagues: on P&IDs, regulators are sometimes marked as TSO – tight closure – or CSC – sealed shut. Both indicate that the valve should not be opened casually. What is the difference between the two? In what situations are each suitable? Can it be replaced freely? Kneeling in gratitudeorz
Are you sure the control valve is sealed with a CSC lead seal?
TSO, or tight shut-off, refers to the metal seal required as a standard for manufacturers when producing valves; it denotes a tight closure, that is, a bubble-level seal = ANSI Class VI. The coating must be dense and the surface finish must be precise. The CSC lead seal is a mechanism intended for valve users, ensuring that the valve cannot be opened arbitrarily at this location as required by the manufacturing specifications. Marked with a lead seal. Once the seal is broken, it indicates that someone has tampered with the valve. In civilian use, old-fashioned gas meters and water meters in your home must be sealed with lead seals to prevent tampering – so as to stop the readings from being reduced or reset to zero. Once it’s damaged, that means you’ve touched it!
CSC can’t be turned off without permission, right?
What did early chemical engineering manuals say? It is now generally considered to mean \"CAR SEAL CLOSED\". Correspondingly, there are also LC: LOCK CLOSE, which means locked closed; NC: NORMAL CLOSE, meaning normally closed; and FC: FAILED CLOSE, meaning closed due to an error. This refers to the automatic closure of control valves in the event of a loss of air supply or power supply.