Maximum Thickness Stainless Steel Cryogenic Service

[Critzy416]

Hello,

I'm looking into a note I found from a pipe specification for cryogenic service, design temperature -325F to +150F: For A312 TP304, the maximum permissible thickness is 6 mm. Per my research in ASME B31.3, I cannot confirm this note. Another engineer in my department found literature in B31.3 relating to carbon steel having a maximum thickness of 0.5 inch for the same service type of service. I understand this relates to the brittleness of the steel at -325F, and resume the note for the stainless steel addresses the same issue.

Has anyone else came across this? Or can point to a standard that addresses this?

Thank you for your time

 

[Gator]

How cryogenic is cryogenic for your service? I can't see CS being used much for liquified gas temperatures.

Piping Design Central

 

[Critzy416]

Gator,

That's an error on my part. The carbon steel 0.5" thickness is limited by -20f design temperature not the -325F service I described for the stainless. Thanks for catching that

 

[Gator]

From my cold box days I recall that we used thin as possible stainless so as to minimize mass and therefore cooldown time. Don't know if this is of any further help.

Piping Design Central

 

[BigInch]

And possible thermal stresses due to maximum temperature differentials across the pipe wall.

you must get smarter than the software you're using.

 

[iainuts]

I'm sure what Gator says about limiting the thermal mass of piping in cold boxes is true, but that isn't to say that there's a structural issue with using thick walled SS where it needs to be thick walled in cryogenic service. Cryogenic pump cylinders for example are commonly made with 304 and can have wall thicknesses over 2" thick when operating at high pressure (ie: 10,000+ psi). They have no problem handling high pressure despite the large thermal gradient across the cylinder wall, and there's no restriction in B31.3 or any other code for that matter. There's no reason to limit pipe to 6 mm for cryogenic service and there's no such restriction on piping in the air separation industry.

 

[OGMetEngr]

It always comes down to what type of service and properties are needed. The thicker the wall, the lower the fracture toughness due to constraint, and more likelihood of sensitization due to welding resulting in lower impact/fracture toughness and corrosion resistance. Sensitization is especially a concern with 304 (vs 304L). What will run through these pipes?

 

[Critzy416]

Gator, BigInch, and iainuts thank you for your feed back. I didn't know about the Cryogenic pump cylinders being so thick. This is good to know.

OGMetEngr, these pipes will see Ethane, Propane, and Butane to name a few; nothing above hydro carbon C5. Like you said, it comes down to the specific application at hand and not using a blanket term.

 

[BigInch]

Any issues are more likely to come with startup and shutdown and their transient thermal stresses across the thick wall. Take that in easy step changes.

you must get smarter than the software you're using.