A nameplate photograph is the cheapest piece of engineering work in a surplus sale. It replaces a site visit, a data sheet search and three phone calls.
Why the nameplate decides the price
A valve is not one item, it is a specification. Two valves of the same size and shape can differ by a factor of ten in value because one has a stainless body and stellite trim and the other is plain carbon steel with a standard seat. The nameplate, the body stamping and the tag are where that specification lives.
When you send a photograph of the plate, the review stops being a guess. Size, pressure class, body material, trim, end connections and often the original service are all captured in one frame. When the plate is missing, everything downstream takes longer and gets more conservative.
Clean it without destroying it
Dust and loose paint hide stamped characters. Wipe the plate with a rag, then use a plastic scraper or a stiff brush on paint. Do not use a wire brush or a grinder: the stamping is shallow, and a wire brush removes the very detail you are trying to read.
If the plate is heavily corroded, take a pencil rubbing. Place thin paper over the plate and rub lightly with the side of a pencil. The rubbing often reads better than the plate itself, and it photographs well.
Take three photographs per model
First, a wide shot of the whole valve so the reviewer can see the pattern, the operator and the general condition. Second, a close, straight-on shot of the nameplate filling the frame. Third, an angled shot of the plate or the body stamping, because low-angle light makes shallow characters readable.
If the valve is one of forty identical units, photograph one of each distinct model and note the quantity. There is no value in forty photographs of the same plate.
Light it properly
Daylight from a doorway or a bright work light placed low and to one side will do more than any camera setting. Straight-on flash flattens the stamping and creates a reflection that hides it. Hold the phone steady, or rest it on the valve body, and tap to focus on the plate rather than the background.
If the plate is dark and the characters are not visible at all, a light rub with chalk or a soft pencil will fill the recesses and make the characters stand out. Wipe it off afterwards.
What else to capture
Photograph the tag as well as the nameplate, because the tag carries the plant's own identification and often the service description. Photograph the actuator and positioner plates separately, since they are separate specifications. And photograph any damage you already know about, rather than leaving it to be discovered.
Send the images as files rather than as screenshots inside a message. Screenshots lose resolution exactly where the detail matters.
Questions sellers ask
How many photographs do you need for a crib of two hundred valves?
One wide shot per shelf, one plate shot per distinct model, and a count. That is usually twenty to thirty images and it is enough to price the lot.
What if the nameplate is completely gone?
Send a photograph of the body shape and any cast markings. Material, pattern and approximate size can often be established, though the price will reflect the uncertainty.
Do you need photographs of the bore and seats?
For high-value valves, yes. A photograph through the bore shows seat condition, erosion and whether the valve is complete.