Wind Overturning Stability

Wind overturning moment on a shell against the dead-weight resisting moment (unanchored tank screening check)

◉ API 650 §3.11.2 (1998, 10TH ED.) AS APPLIED IN HPCL ENNORE TERMINAL CALCULATION · NOT A REGULATORY SUBMISSION TOOL

⚠ Indicative tool only. Source: a real project calculation (Hindustan Petroleum Corporation, Ennore Terminal, Feb 2009) applying API 650 (1998, 10th ed.) §3.11.2, under which the overturning moment due to wind must be less than ⅔·(W·D/2). This is a project calculation applying the code, not the code text itself, and it uses the older edition's criterion — later API 650 editions restate the overturning check (§5.11) with different load combinations and factors, so treat this as a screening check and confirm the criterion against the edition your project specifies. The base wind pressure (0.86 kPa on the projected area of a cylindrical shell, referenced to 190 km/h) and the mid-height resultant (H/2) are taken from the HPCL example and are editable inputs, not verified against any edition. Reproduces the HPCL numbers to within rounding: the source rounds the wind correction factor C to 1.31, while this tool carries it unrounded (1.3132), so it reports M ≈ 8,209 kN·m against the source's 8,189 kN·m.

Identification

Company

Tank ID

Location

Record Type

Research entries stay private to you for practice/testing. Switch to Official once this is a real design your company should see.

Wind Load

Basic Wind Speed, V_b km/h

Risk Coefficient, k1

Terrain/Height/Size Factor, k2

Topography Factor, k3

Reference Wind Speed for Base Pressure km/h

Base Wind Pressure on Projected Area kPa

Allowance for Structurals & Misc. %

Projected Width (Shell Outside Diameter) m

Shell Height, H m

Nominal Diameter, D (for resisting moment) m

Design speed V = V_b·k1·k2·k3 (IS 875 factors in the HPCL example; set all three to 1 and enter the design speed directly if you are not using IS 875). Correction factor C = (V / reference speed)².

Resisting Dead Weight

Dead Weight Available to Resist Uplift (corroded shell + attachments supported by shell) kg

Result

Overturning Check Not evaluated

Design wind speed, V—

Wind correction factor, C—

Projected area—

Wind load on shell (C × p × area)—

Total wind load, P (incl. allowance)—

Overturning moment, M = P × H/2—

Dead weight, W—

Resisting limit, ⅔·(W·D/2)—

Utilisation, M / limit—

Passes when M is less than ⅔·(W·D/2). If it does not, the tank would need anchorage or additional resisting weight under this criterion.

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