Tank bottom plate thickness

[fosespirino]

Would anyone assist in calculating the bottom (not annular) plate thickness of a 50 cubic metre crude oil storage tank, with regards to API 650.

The copy I have does not seem to address it.

Regards

 

[IFRs]

There are no calculations for bottom plate thickness. They must be 1/4" plus corrosion allowance. See below:

API 650 Section 5.4.1: All bottom plates shall have a minimum nominal thickness of 6 mm (0.236 in.) [49.8 kg/m2 (9.6 lbf/ft2) (see 4.2.1.2)], exclusive of any corrosion allowance specified by the Purchaser for the bottom plates.

 

[fosespirino]

IFRs,

Would it be right then to accept a deisgn that has different thickness for the bottom and annular plate?

For example, are these values tenable?

Bottom plate (plus corrosion allowance)- 6mm + 4mm

Annular plate - 20mm

Regards

 

[JStephen]

The annular plate is quite frequently made thicker than the remainder of the bottom plate.

 

[DSB123]

forsespirino,
If you are the engineer performing the assessment or the guy accepting the "Design" then surely you must be competent enough to make a sound judgement on the "Design" of the Tank and ensure the calcs show that the "Design" both meets the Code requirements and is also fit for service!!! Asking on this forum whether a 20mm thick annular is acceptable will not yield an answer as the annular thickness is dependant upon the loading applied so it's impossible for anyone to say whether it's acceptable without reviewing the calculations or performing them again knowing all of the facts.