Buoyancy, damaged-flotation, and support design load checks for internal floating roofs (API 650 Appendix H.4.2)
◉ API 650 APPENDIX H.4.2 STYLE CHECK · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. Verified directly against Appendix H text. Two things this tool deliberately does NOT compute: (1) the "float undamaged after any two compartments are punctured and flooded" check (§H.4.2.1.3) requires compartment-by-compartment displacement modeling specific to the actual deck layout — shown here as a design requirement to satisfy, not a formula; (2) the support load combination's point-load term (L/2, a literal 2.2 kN over 0.1 m²) isn't combined into one number with the uniform-load terms (Pte, Ln), since doing that validly requires the actual support's tributary area, which the standard doesn't provide a formula for either — both are shown side by side for you to compare against your own support geometry.
Identification
Research entries stay private to you for practice/testing. Switch to Official once this is a real design your company should see.
Roof Type & Design Basis
Result
Design specific gravity (§H.4.2.1.1: lesser of product SG or 0.7)—
Required buoyancy is at least 2× dead weight, plus additional buoyancy to offset seal friction during filling — the standard doesn't quantify the friction allowance, so add your own margin for it on top of the 2× figure below.
Result Not evaluated
Minimum required buoyancy (2 × dead weight, before seal-friction margin)—
Available vs. required—
Damaged-Flotation Requirement (§H.4.2.1.3, design requirement to satisfy)
The roof shall float without additional damage after any two flotation compartments are punctured and flooded. For open-center-deck types (b, c, g) in contact with the liquid, the center deck must also be assumed flooded along with the two compartments. Tanks ≤6m (20ft) diameter may, with Purchaser agreement, be designed to the single-compartment-loss basis instead. This check depends on the actual compartment layout and isn't reducible to a single formula here — verify against your own compartment displacement model.
Concentrated Live Load (§H.4.2.1.4)
Result
Point load (two men walking), anywhere on roof2.2 kN over 0.1 m² (500 lbf over 1 ft²)
Support Design Load Combination (§H.4.2.2.2)
Load = Dr + greater of (Pte, Ln, L/2). Enter Dr, Pte, and Ln as reactions already converted to your support's tributary area.
Result
Ln — uniform live load—
Governing uniform-load case: Dr + max(Pte, Ln)—
Separate point-load case to compare: Dr + L/2 (2.2 kN / 0.1 m²)—
Support Cable Allowable Load (§H.4.2.2.3) if cable supports used