Normal flotation, 10-inch rainfall deck deflection, and a simplified punctured-compartment tilt check for single-deck pontoon roofs
◉ HPCL ENNORE TERMINAL FLOATING ROOF CALCULATION (API 650 11TH ED. BASIS) · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. Source: a real project calculation (Hindustan Petroleum Corporation, Ennore Terminal, Feb 2009) for a 33 m single-deck pontoon roof. These are that engineer's simplified design-office methods, not code text: the pass/fail limit (liquid height < 0.7 × rim height) is HPCL's own criterion and is an editable input. Reproduces the HPCL example closely — flotation to <0.01 mm, rain deflection 192.2 mm (HPCL assumed 192 mm; this tool iterates to convergence), centroid and area to 4 digits.
Two departures from the source, stated openly. (1) In the punctured-tilt check, HPCL reports the depth at point B as 0.299 m. Recomputing from HPCL's own intermediate values with a linear stress distribution (W/A + M·y/I) gives 0.425 m (0.419 m above the pontoon bottom plate) — still inside HPCL's 462 mm limit, so their conclusion stands, but with less margin than reported. The 0.299 figure is reproduced exactly only by evaluating (dA·L − w)/L rather than dA·(L − w)/L (or the full stress form), so it appears to be an arithmetic slip in the source; this tool uses the linear stress distribution. (2) The second moment of area I computes to 22,122 m⁴ from the stated formula against 22,208 m⁴ in the source (−0.4%; effect on depth < 0.0003 m); the source's value could not be reproduced exactly. The tilt check is a beam-analogy approximation and is a different method from the rigorous volume-balance calculation in the Punctured Floating Roof Buoyancy Check tool — the two are not expected to agree numerically.
Identification
Research entries stay private to you for practice/testing. Switch to Official once this is a real design your company should see.
Roof Geometry & Weights
Weights are in tonnes (t); pressures in t/m². WR = WD + WP.
1. Normal Flotation (no rupture, no water)
Pontoon-ring buoyancy = π(R1²−R2²)·depth·SG; the remaining roof weight is carried by liquid head h1 over πR1² measured from the bottom of the deck plate. The code-basis low-SG case is 0.7.
2. Rainfall Condition (deck deflection)
Large-deflection clamped circular plate: Y = 0.662·a·[p′·a/(E·t)]1/3, with the deflected-deck water volumes updating the load, iterated to convergence. E = 20,470,000 t/m² ≈ 200.8 GPa.
Intact ring sector half-angle α = π(n−k)/n. Depth = (W/A + M·y/I) / SG, with point A at the outer edge (y = R1 + Xc) and B at the inner edge (y = R1 + Xc − w). The check at A is an addition to the source, which shows only the inner-rim (B) check.