Storage Tank API 650 - Design External Pressure
Storage Tank API 650 - Design External Pressure
(OP)
Hello,
I have a SS-304 storage tank with 1" insulation (ID=14 feet X 20 feet High and self supporting cone roof). I am using Tank software for analysis purpose. In Tank software, under external pressure analysis - specify external pressure (Pe)in lb/ft^2.
I have a client with 40 Yrs old tank. The drawing did not have any design condition so what is the best guess?
Please, Can some one explain regarding design external pressure. What will be the value?
I am using -1.73 inch of water OR -8.999 lb/ft^2. Is it correct??
I appreciate it.
Thanks - Mayur
I have a SS-304 storage tank with 1" insulation (ID=14 feet X 20 feet High and self supporting cone roof). I am using Tank software for analysis purpose. In Tank software, under external pressure analysis - specify external pressure (Pe)in lb/ft^2.
I have a client with 40 Yrs old tank. The drawing did not have any design condition so what is the best guess?
Please, Can some one explain regarding design external pressure. What will be the value?
I am using -1.73 inch of water OR -8.999 lb/ft^2. Is it correct??
I appreciate it.
Thanks - Mayur





RE: Storage Tank API 650 - Design External Pressure
RE: Storage Tank API 650 - Design External Pressure
With the 1" of water column, no calculations are required for the vacuum condition.
In the current standard, the 1" vacuum is accounted for in the roof loading (with 40% factor) and in the shell stability calculations/ wind girder calculations.
For a 40-year old stainless tank, it was built prior to Appendix S, so it may not comply with Appendix S.
RE: Storage Tank API 650 - Design External Pressure
Think of your humble Coke can. It can handle high internal pressures, but with much much less than 1 bar across it it will crumple inwards very easily
For a tank this only relates to instances when the tank is empty usually, but on any negative pressure compared to atmospheric pressure, the strength of a tank is very low.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Storage Tank API 650 - Design External Pressure
Don't understand why the OP is concerned about the external pressure unless he is planning to steam clean or make a boat.
RE: Storage Tank API 650 - Design External Pressure
I appreciate your input and time.