In the thread with the subject of "API 650 statement" LittleInch has provided following statement from API 650:
Appendix F states that if the pressure is less than 1kPa (4 inches of water), then it is classed as "atmospheric" Design pressure higher than that up to 18 kPa needs Appendix F to be applied.[unquote]
i have the Edition of 2007 in which i don't find such statement especially the first part about the design pressure of less than 1kpa which doesn't need using appendix F.
I want to know such statement can be found in which Edition of API 650?
12th edition march 2013 including errata July 2013 and December 2014.
I think is taken out of context though. The flow chart in appendix F starts with section 1.1.1.
1.1.1 - Pressure "approximating atmospheric pressure ( internal pressure not exceeding the weight of the roof plates)" are "basic design", not appendix F. The 1 kPa/ 4 inches of water turns up in section F2 and imply that this is also covered by basic design.
But first and foremost work out the weight of your roof then work out the pressure required to lift it. internal pressure lower than this - "atmospheric", higher - start to look at other sections.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Then, we can conclude there is no such limitation value (1 kpa) in API 650 and one can determine minimum design pressure using the tank roof weight and surface area. Am i right?
In the current API-650, if the design pressure is less than the weight of the roof plates, then it still needs to be included in the overturning evaluation of 5.11, the anchorage sizing of 5.12, and the overturning evaluation of E.6.2.1.1.1, and any of those sections might further limit the pressure.
