Cryogenic & High Pressure

[Weko]

Currently I am looking towards a FEED for refrigerant CNG. The idea to cool down the CNG was to obtain the "optimum compression storage" between pressure and temperature.

My question is that on the material spec for class rating 150# and 300# they used SS 304L. But after compression, the rating becomes 900# / 1500# , and they mention the material is SS 321L.

Does anybody have an idea why they mention 321L?

I am working in an Asian country where SS304L is relativaly more easily to obtain, rather than SS321L

 

[TomEun]

One of the reasons to select 321 SS instead of 304 SS is due to the different maximum working pressure (MWP) at elevated temperature (321 SS is higher than 304 SS). Please compare the MWPs for two metals in ASME B16.5.

Thomas Eun

 

[EdStainless]

There are some other austenitic SS grades that have higher strength at low temps.
Check out the Code and look at both lower temp rating and the allowed stress.
Maybe you can find another option, but I sort of doubt it, 321 is fairly standard for this service.

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