One of the key regulator failure scenarios is allowing higher downstream pressure than permissible. For this reason, a proper gas train features independent protection devices.
Monitor regulator
It can take over regulation if the active regulator fails.
Slam-shut
It completely shuts off the supply when the pressure exceeds the defined limit.
Relief valve
It can limit pressure by releasing a controlled amount of gas, where permitted by design.
Coordination
Setpoints must be properly prioritized so that each level of protection acts in the intended sequence.
Basic principle
We do not rely solely on the main regulator for downstream network protection.
