Storage Temperature vs. Design Metal Temperature 1

[Dome Design]

Hello dears, I've searched too much but still confusing while I'm looking for temperature values which concern me for applying it to my dome roof calculations. As my knowledge, design metal temperature is basically about the tank shell. But should I consider it also for my dome roof? According to product owner, storage temperature is 85°C and maximum design metal temperature is 175°C. Since this value is too much for an aluminium structure, any comment can be helpful, thank you and have a nice work days!

 

[IFRs]

Where did you find that 175DegF is too high for an aluminum structure?

 

[Dome Design]

Sir it is not Fahrenheit, it is celsius. Sorry for misunderstanding

 

[IFRs]

I'm an idiot - you clearly said degrees C in your original post.

API does not distinguish between product, tank or dome roof - if the max design metal temperature is 175C for the tank, the same would apply to the dome roof. You can not use an aluminum dome for this tank and be in compliance with API 650.

 

[Dome Design]

Dear Sir firstly, thank you for replying. As my research, API says design metal temperature can be considered 8°C more from ambient temperature if it is not mentioned(Section 3.6). At this moment, I have another question, if the storage temperature is 85°C, how it is possible to reach these values for design metal temperature and also for Fuel Oil product, I have designed dome roofs also for different customers but according to their datasheet "design" temperature was max 85°.

 

[Geoff13]

In API 650 the design metal temperature is the "lowest temperature considered in the design" and thus the 8°C difference isn't applicable for the maximum design temperature.

API 650 does not suggest how the maximum design temperature should be chosen, other than it must be higher than the operating temperature. You will likely have to ask your customer why there is such a large difference between the storage and maximum temperatures they have called for. Sometimes customers have good reasons for this difference (upset conditions vs. storage conditions) and other times they are just being overly conservative without understanding the implications. It is often helpful in these discussions if you can show them the cost extra to meet the maximum temperature they have specified.