Mechanical isolation - Double isolation and emptying
Single valve assembly that seals the pipe by closing the valve on the main line with a relief valve between the valves
Double isolation and empting have two valves closed with a relief valve in the middle
Automatic valves should not be used for isolation. If used, the valve must be closed and then disabled
The pressure relief valve shall be sized to meet the requirements for the maximum possible discharge that can be passed when the isolation valve is closed
Process control valves cannot be used as basic isolation
