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API-650 Stainless Steel Minimum Thickness and Design Temperature

API-650 Stainless Steel Minimum Thickness and Design Temperature

API-650 Stainless Steel Minimum Thickness and Design Temperature

Dear Sirs/Madams,

I am a Chemical Engineering and, therefore, not the right professional to specify storage tanks for industrial aplications, but recently I have specified a process data sheet for an atmospheric tank to storage liquid fatty acids at 60 Celsius degree and choose the API-650 12th version as the standard to be addressed. Soon I have discovered the tank design temperature must not be above 93 Celsius degree and my SS304 plates thickness must not be less than 5 mm (3/16").

Please, does anybody know why the standard set these requirements?

Thanks for your help in advance.

Best Regards,

Luís - Brazilian Chemical Engineering (Graduated 86')

RE: API-650 Stainless Steel Minimum Thickness and Design Temperature

Some of the minimum thicknesses are for constructability and maintaining dimensional tolerances. Thinner plate is difficult to butt weld and will warp when welded.

RE: API-650 Stainless Steel Minimum Thickness and Design Temperature

The 93 Celsius is not applicable. The base version of API-650 is limited to that, but it is extended up to 500F in Annex M and also in Annex S.
For larger tanks, minimum thickness will be affected by wind design. For smaller tanks, by handling in the shop.
UL-142 allows some thinner material, but has its own drawbacks that may make it undesirable for this application.

RE: API-650 Stainless Steel Minimum Thickness and Design Temperature

Dear IFRs and JSephen.

Thank you very much for your enlightments.

Have a nice weekend.
Best Regards,


RE: API-650 Stainless Steel Minimum Thickness and Design Temperature

I have seen thinner tanks, especially ones made from lean duplex SS, but they had a lot of stiffening rings and other features.
So, less metal but more difficult to build.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: API-650 Stainless Steel Minimum Thickness and Design Temperature

lcms, you might direct further questions on this subject to the Storage Tank Forum.



The problem with sloppy work is that the supply FAR EXCEEDS the demand

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