A control valve is a system. Break it into parts and you have sold a valve and some instruments for less than the system was worth.
The system is the product
A control valve assembly is matched: the body, the trim, the actuator size, the spring range, the positioner and the tubing all work together. That match is what makes the assembly usable, and it is what a buyer is paying for.
Split it and you have a body that needs an actuator, an actuator that needs a bracket, and a positioner that needs a valve. Each part has a market, but the sum is lower than the assembly.
Documentation follows the assembly
The tag, the data sheet and the calibration record belong to the assembly, not to the body. Once the parts are separated, the paperwork becomes ambiguous and the value falls accordingly.
This is why we ask sellers to photograph the assembly before anything is disconnected. The photograph preserves the match even if the physical assembly is later broken.
The same applies to relief valves
A relief valve with its cap, lever, bonnet and pilot is a relief valve. Without the pilot, a pilot-operated valve is a body and a bonnet. Without the cap and lever, it is a valve that has been opened and left.
Relief valve parts are specific to the model and often unobtainable. That makes completeness more important than in almost any other category.
How to keep assemblies together in a cleanout
Palletise by assembly, not by component. Band the valve and actuator together if they have already been separated. Tag both halves with the same number.
Brief whoever is doing the removal. Most separation happens because somebody was told to make the load smaller, not because anybody decided to break up a valve.
When separation is unavoidable
If an assembly must be split for transport, keep the parts together and label them as a set. A crate containing a body, its actuator and its positioner, labelled as one item, is still an assembly.
What destroys value is mixing parts from different valves in one box. That is the one outcome worth avoiding.
Questions sellers ask
Do you pay more for complete assemblies?
Yes, generally. The premium varies by type but it is consistent.
What if the positioner was already removed?
Keep it with the valve and tell us which one belongs to which. A matched pair is still worth more than two separate items.
Are bare bodies worth buying?
Yes, as rebuild candidates, but at body value rather than assembly value.