During recent years more attention has had to be given to the safety of piping systems because of large-scale disasters and the harsher offshore environments where oil and gas facilities are now constructed. Safer operating environments are required not only to protect profits, but more importantly to protect plant personnel, without whom the former would not be achievable.
Every valve, even the very smallest drain valve, has a role to play in the safe and efficient operation of a process plant. Put in its simplest form a valve can be open, closed, or in a position somewhere in between to control the process flow. All valves are important, however, some valves are naturally more important than others, especially in main process flows and in piping relief systems.
During the design stage of a process plant, the Process Engineer will identify some critical valves that must be securely sealed open or sealed closed. These chosen valves are marked on the piping and instrument diagram (P&ID) as CSO or CSC. This stands for Car Sealed Opened and Car Sealed Closed.
This terminology dates back to the very early days of the petroleum industry and it originates from the railroads. Huge quantities of grain and other produce have always been freighted by the railroads all over the United States and there had to be a cheap and efficient method of securing this cargo from theft or illegal passengers boarding the train. The cargo, in most...
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