BZ29
Mechanical
- Jul 26, 2010
- 37
Please correct & guide me if my understanding is wrong regarding these two issues:
1) With Ref to API650 5.2.1(b), upto 0.25kpa external pressure, no calculation is required (safety against such vacuum is inherently built in its internal pressure design). Annex-V is for pressure above 0.25kpa only.
I was just going through a design using HEXAGON TANK Software, having 0.25kpa external pressure. It is showing calculations for Annex-V even at external pressure less than 0.25kpa and gave warning that it failed the annex-v calculations, and need stiffeners, although it was safe for internal pressure. I am assuming that i can ignore this calculation & warning, unless that value exceeds 0.25kpa.
2) If intermediate stiffeners are required as per its calculation (supposedly 1 stiffener is required), while stiffeners are also required as per Annex-V due to vacuum (supposedly 2 stiffeners are required). i assume we can size and place them to suit both requirements, and will use 2 stiffeners in total, instead of 3.
1) With Ref to API650 5.2.1(b), upto 0.25kpa external pressure, no calculation is required (safety against such vacuum is inherently built in its internal pressure design). Annex-V is for pressure above 0.25kpa only.
I was just going through a design using HEXAGON TANK Software, having 0.25kpa external pressure. It is showing calculations for Annex-V even at external pressure less than 0.25kpa and gave warning that it failed the annex-v calculations, and need stiffeners, although it was safe for internal pressure. I am assuming that i can ignore this calculation & warning, unless that value exceeds 0.25kpa.
2) If intermediate stiffeners are required as per its calculation (supposedly 1 stiffener is required), while stiffeners are also required as per Annex-V due to vacuum (supposedly 2 stiffeners are required). i assume we can size and place them to suit both requirements, and will use 2 stiffeners in total, instead of 3.
