Lined valves put a corrosion barrier between the process and a structural body, usually cast or ductile iron. PTFE and PFA cover acid and solvent service, glass covers aggressive chemistry at higher temperature, and rubber covers abrasion and caustic duty.
Lined bodies are expensive and are usually replaced on condition rather than on schedule. That means surplus lined valves are often in reasonable order, and the inspection question is always the same: is the lining intact, and can we see it?
Review points
What decides the value of lined valves valves
Lining condition
Photograph the bore. A blister, a breach and a discoloration are three different things.
Lining type
PTFE, PFA, glass, hard rubber and soft rubber have different values and different buyers.
Body integrity
The iron body behind the lining must be sound. External corrosion is a warning sign.
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 valves with lining damage?
Sometimes. Describe it precisely and send a photograph of the bore.
Which lining is most valuable?
PFA and PTFE generally, with glass and hard rubber close behind in the right pattern.
Are lined butterfly valves purchased?
Yes, in quantity and in good condition.