Bronze gate, globe and check valves cover small-bore water, steam, air and marine service. They resist corrosion in fresh and salt water, they are cheap, and they are produced in enormous quantities, which is why every plant store has a box of them.
Value in bronze is driven by quantity, pattern, size and whether the valves are new. A single used bronze gate valve is worth very little; a boxed lot of fifty is a straightforward purchase.
Review points
What decides the value of bronze valves
New old stock
Unused bronze valves in original packaging are worth substantially more than used ones.
Threads
Damaged NPT threads reduce value sharply.
Marine versus utility
Marine bronze with naval brass trim is a distinct and stronger market.
Selling it
How to present the lot
Count by size and pattern, and note the marking on the body. If you have certificates, include them; if you do not, say so rather than implying they exist.
Do not separate trim from bodies to sell them individually unless the trim is clearly identifiable and valuable on its own. In most cases the assembly is worth more together.
Questions sellers ask
Do you buy bronze by the box?
Yes. Around thirty to fifty pieces makes a worthwhile lot.
Is bronze scrap value relevant?
Only as a floor. Usable valves are priced as valves.
What about leaded bronze?
Still purchased for utility service, though some buyers avoid it for potable water.