sajk14
Mechanical
- Sep 2, 2009
- 56
Hello all,
I am looking at Annex C External floating roofs in API 650 - 12th Edition.
Clause C.3.4.1 (a) states that floating roofs shall have sufficient buoyancy to remain afloat with 250mm of rain fall over the full horizontal tank area. i.e. total volume of rainwater in m³ = 0.25 x Pi*D²/4, where D is the full inside diameter of the tank (in m).
Clause C.3.4.2 states for pontoons with single decks, the pontoons must have adequate strength to prevent distortion when the centre deck is loaded by the design rainwater (as above).
Does it seems excessive to assume that the total volume of rainwater based on the full tank diameter acts on the centre deck area only?
What if say for example you had a scenario for a floating roof where the deck area is not large enough to contain the full volume of the rainwater calculated. I.e the rainwater would then overspill onto the pontoon area?
With regards to calculating the stresses in the pontoon is it ok to take the full pontoon geometry into consideration for cross sectional area, Section Modulus etc..provided the pontoons are fully stiffened? i.e. Each Pontoon compartment stiffened by using a number of beams attached radially to the top and bottom pontoon plates. Also using a heavy pontoon inner rim plate thickness where the deck plates are connected to the pontoon.
I appreciate any thoughts or feedback on the above.
I am looking at Annex C External floating roofs in API 650 - 12th Edition.
Clause C.3.4.1 (a) states that floating roofs shall have sufficient buoyancy to remain afloat with 250mm of rain fall over the full horizontal tank area. i.e. total volume of rainwater in m³ = 0.25 x Pi*D²/4, where D is the full inside diameter of the tank (in m).
Clause C.3.4.2 states for pontoons with single decks, the pontoons must have adequate strength to prevent distortion when the centre deck is loaded by the design rainwater (as above).
Does it seems excessive to assume that the total volume of rainwater based on the full tank diameter acts on the centre deck area only?
What if say for example you had a scenario for a floating roof where the deck area is not large enough to contain the full volume of the rainwater calculated. I.e the rainwater would then overspill onto the pontoon area?
With regards to calculating the stresses in the pontoon is it ok to take the full pontoon geometry into consideration for cross sectional area, Section Modulus etc..provided the pontoons are fully stiffened? i.e. Each Pontoon compartment stiffened by using a number of beams attached radially to the top and bottom pontoon plates. Also using a heavy pontoon inner rim plate thickness where the deck plates are connected to the pontoon.
I appreciate any thoughts or feedback on the above.
