Material and pressure class decide what a valve can do, and they decide what a used valve is worth. A stainless body has a floor under its price that a carbon steel body does not. A Class 900 casting weighs several times what a Class 150 casting weighs at the same size.
The pages below cover the grades that turn up most often in Gulf Coast surplus, plus the six ASME classes that define pressure rating. Each one explains what the material is for, what to look for, and why the marking matters.
Materials
Body and trim grades
- 01 WCB Carbon SteelThe default valve material for non-corrosive process duty, and the largest single category in any plant crib… →
- 02 316 Stainless SteelThe workhorse stainless grade. 316 valves hold value far better than carbon steel, even when they have been … →
- 03 Alloy SteelChrome-moly bodies for high temperature and hydrogen. Alloy valves are the most documentation-sensitive carb… →
- 04 MonelNickel-copper for seawater and aggressive chemistry. Monel valves are rare, expensive and worth a careful lo… →
- 05 HastelloyHigh-nickel alloys for the worst chemistry in the plant. Hastelloy valves are few, expensive and highly reco… →
- 06 Duplex StainlessHigh-strength stainless for chloride service and offshore duty. Duplex valves are expensive, specified caref… →
- 07 Cast IronHeavy, cheap and everywhere. Cast iron valves sell on size and quantity, not on brand.… →
- 08 BronzeSmall, plentiful and still specified. Bronze valves are a volume category, priced by the box.… →
- 09 PVC and CPVCPlastic valves for aggressive chemistry and pure water. In quantity they are a clean, easy surplus category.… →
- 10 Lined ValvesThe lining carries the value. A sound lined body is worth many times its weight in scrap.… →
- 11 ASME Class 150The most common pressure class in the plant. Class 150 valves are bought in bulk and sold in bulk.… →
- 12 ASME Class 300The middle of the process range. Class 300 valves are common enough to be easy to sell and heavy enough to b… →
- 13 ASME Class 600Higher pressure, heavier castings, better resale. Class 600 is where surplus valves start to carry real valu… →
- 14 ASME Class 900Heavy, expensive and documented. Class 900 valves are a small part of a crib by count and a large part by va… →
- 15 ASME Class 1500High-pressure hardware where the casting is the value. Class 1500 valves are rare, heavy and always worth a … →
- 16 ASME Class 2500The top of the standard range. Class 2500 valves are few, costly and almost always worth reviewing individua… →
Pressure class
What the number means
ASME class is a pressure-temperature rating, not a pressure in psi. A Class 150 valve is rated for a lower pressure as temperature rises, and the class determines flange dimensions, wall thickness and bolting. It cannot be substituted or upgraded after the fact.
For a seller, the practical point is that class affects both the metal content and the market. Class 150 valves are common and cheap; Class 900 and above are rare, heavy and documented.