API-650 Stainless Steel Minimum Thickness and Design Temperature 4

[lcms]

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')

 

[IFRs]

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

 

[JStephen]

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.

 

[lcms]

Dear IFRs and JSephen.

Thank you very much for your enlightments.

Have a nice weekend.
Best Regards,

Luís.

 

[EdStainless]

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

 

[SnTMan]

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

Regards,

Mike

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