Storage Tank Stiffener ring location (Inside or outside) 2

[passion1205]

Dear Elites.

I am the mechanical design engineer for storage tank API-650.
Intermediate wind girder (or stiffener ring) is usually attached outside of the tank shell.
But in case of LNG storage tank which is in accordance with API-620, stiffener ring is attached inside of tank shell.
Is there any special reason for this inside location? due to the insulation between inner shell and outer shell?

 

[Soln]

That seems plausible- maybe a constructability issue. With the stiffener inside, they were able to run equipment in the gap between tanks...?

 

[IFRs]

If placed on the outside of the inner tank, stiffeners would interfere with the insulation and the welding equipment.

 

[Duwe6]

gotta quibble with IFR's anfswer. When coordinated with the insulation contractor, stiffening rings will act as insulation supports, significantly assisting the application of insulation by giving it a place to rest on, and something to secure it to.