Full bore control valves


Thread Starter

F. Ataei

What's the difference between "Full bore control valve" and "Reduce bore control valve" ?
What is the application of "Reduce bore control valve" ?
A full bore control valve will allow 100% flow when it is open fully, A reduced Bore valve will only allow a proportion of 100% when fully open.

Reduced bore valves tend to be cheaper!

I cannot think of any applications for them apart from ones which full flow are not needed, but then it is more economical to use the right size pipe in the 1st place!


In any control situation that has a valve involved, the most critical thing in the loop is the correct sizing of the control valve. If the valve flow rate is too high then you are trying to control at very small valve opening or conversly if the valve is too small then you cannot get the desired flow.If its a shut off valve the full bore is used as its a cheap option.

Full bore valves are such things as ball valves, butterfly valves and knife gate. very non linear giving 80% of flow with 20% valve opening. These days rely heavily on smart positioners to give control.

reduced bore valves are globe valves, plug valves and ball valves with restriction. Designed for the valve itself to meet flow conditions. (generally controlling around the 50% mark) then with a good positioner gives very good control of process. This reduces costs.


Bruce Durdle

You can get say a 3" valve with say a 2" full-bore trim. This will give you the maximum CV for that particular body style. However, you can also buy a "reduced trim" (possibly down to 1/2") for the same valve body.

Now, when the process engineers get into their stride in the debottlenecking process and find they can squeeze 140% of nominal production out of the plant if only your valve was a bit bigger, you can (relatively) quickly and cheaply pull out the reduced trim and substitute a larger one - instant plant upgrade with no need to rework the pipes to cater for a physically bigger valve.

Reduced trim valves should be considered for any applications where the flow through the valve is critical to plant throughput and data available during initial sizing is not very reliable.