Problems with the installation of root valves
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For the import of a certain device, a root valve was originally installed; later, a control system was required, so a control valve assembly was added, comprising two gate valves at the front and back as well as a bypass stop valve. The engineers removed the original root valve – is this feasible?
This is a rather uncommon situation. It is recommended to keep the inlet and outlet valves of the equipment.
No, one point turns into two points; their functions are different. In an emergency, closing one valve becomes closing two valves. Made a simple problem complicated.
The engineer removed the original root valve; it’s not feasible
Could you explain it in more detail? What are the two operating conditions when using the control valve normally versus using the bypass alone?
It’s better to keep it; although self-regulating valves also have front and rear shut-off mechanisms, they should function properly under normal conditions. However, in the event of internal leakage or any emergency situation, the root valve can be closed directly
If the distance of the pipeline leading to the control valve assembly from the equipment is short, this pipeline does not interfere with equipment maintenance, and the likelihood of problems occurring during normal operation is low. The isolation valves and bypass valves located before and after the control valve assembly can be closed tightly to prevent leaks, thus not affecting maintenance; in fact, they can even be removed.
It’s better to keep it; although there is a gate valve behind the control valve, this gate valve actually belongs to the control valve itself and does not have the characteristics of a root valve.
Is the control valve assembly replacing the root valve in its original position? If that’s the case, it’s fine to remove the root valve – an extra valve means an additional point of leakage.
Let’s think about it from another angle: without achieving self-control, and without using control valves or inlet and outlet isolation valves, will your root valve still not experience internal leakage? It will. Generally, whether to use it or not isn’t really a big issue; for aesthetic reasons and to save costs, it is recommended to use the root valve as a regulating valve as well as a shut-off valve.
That’s what the process engineers think; they recommend placing the control valve assemblies around the equipment, and piping work is carried out in accordance with this recommendation. For different projects, some owners consider this to be advantageous, as it allows operators to use the bypass valve while simultaneously monitoring the local instruments on the equipment. However, when there are many devices of the same type, some owners consider this approach unsuitable; they suggest placing the control valve assemblies in one location for unified operation, which means they are further away from the devices compared to the previous solution.