Do you need a pressure vessel? Do you not have a preferred supplier for such things? Or maybe you’re sick of the one you have, or want to comparison shop, or just in a rabbit hole of supplier searching but adding “ASME” into your search terms isn’t getting you where you need to go?
Well, you’re in luck, because all current ASME certificate holders are listed here:
[Mods: This is definitely not the right category for this, but I couldn’t really find an appropriate one. Maybe we need an Equipment/Sourcing/Process Engineering/Big Steel Stuff type category?]
I’m not aware of any specific collections of links other than the all-knowing one.
I believe U-stamp is the thing to search for. I’m not aware of the difference between U/U2/U3 off hand but I’m sure that detail is published somewhere.
U stamp is for division 1 vessels. They don’t require a PE for the design calculations and are somewhat limited (for instance, breach lock vessels are difficult under a U stamp). Basically any ASME shop has this stamp.
U2 us for Div 2. This allows using FEA and making some design choices to get a more “efficient” design, but still has substantial safety margins. It requires a PE stamp.
U3 is for high pressure vessels that are insane to build under U or U2 because of the safety factors. It requires fracture toughness, way more NDT, and two PE stamps. It lets you proof your vessel completely computationally. For reference, our 20ksi 20L vessels manufactured from 17-4PH would need a wall thickness over 3" for a U stamp (ignoring the closure which is impossible under U) and are only ~.8" under U3. That being said, they have to be trepanned from solid bar which is insane lol. U3 is big boy stuff and last I checked there are less than 30 companies holding that stamp.
At the end of the day though, they’re all really as “safe”. U2 and U3 are usually for economics/functionality that isn’t possible under U