Silo Design
Category:support request

Dear All,

I am designing a silo of 100M^3. Stainless steel is the material used for the plates for roof, shell, and hopper. Mild steel is the material for below the hopper and shell joint. The material stored is plastic resin with density 700 kg/m^3.

I am following IS 9178 (Part I, II, & III) for design. I have few questions for you.
1. Is this code applicable for stainless steel material? If not, which code shall be followed?
2. Is it must to keep minimum hopper slope of 60 degree (Part I page no. 17)?
3. Page no. 20 Part II: If diameter of tank is 4 m and hopper slope is 60 degrees which makes height of silo to be 10.3 m (which includes hopper height and above it) this height excludes the gap between hopper bottom and ground surface, as per 11.3.2 horizontal and vertical stiffeners shall be provided at 100 t or 1000 mm whichever is less. Do we have to strictly follow this? I have provided stiffeners as per this clause which comes out to be at 500 mm spacing for horizontal and vertical stiffeners for shell material thickness of 5mm. Client has commented that this is too much and in my defense I have shown this clause. Can we increase the spacing and what is the basis to increase it?
4. Page no. 21, Part II: Minimum thickness of stainless steel material shall be 5 mm in the case of stiffeners. Client has commented that 4 mm shall work as this what they are using. I have shown code in my defense.
5. How much can we deviate from codes as consulting structural engineer? In case of failure, what will be legal take on this?

I request you to spare some time to answer my questions out of your busy schedule.

With Regards,
Rahul Sharma