Tanker Cargo API Gravity, Density, VCF & Standard Volume Tool

API Gravity • Density • CTL / CTPL / VCF • Live Tank Charts • TOV → GOV → GSV → NSV • Free Water • S&W • Ship/Shore Reconciliation

Tanker Cargo API Gravity, Density, VCF & Standard Volume Tool

Convert tanker cargo observations into transparent standard-volume and mass quantities without pretending to reproduce licensed ASTM/API petroleum tables. Simple mode handles one cargo quantity using a certified correction factor, measured density ratio or clearly labeled thermal-expansion estimate. Advanced calculates multiple tanks, combines free-water and S&W deductions, converts API gravity and 60°F density, applies optional pressure correction, reconciles ship versus shore/B/L quantities and exposes every tank’s correction chain.

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For custody-transfer work, use a current licensed/API-approved VCF/CTL result and select Certified Factor. The alternative density-ratio and thermal-expansion methods are transparent engineering calculations, not substitutes for ASTM D1250 / API MPMS 11.1 implementation.

Quantity chainTOV → GOV → GSV → NSV

QualityAPI / density reference

Outputm³ / bbl / tonnes

Cargo Observation

Observed volume basis

Observed volume m³ at observed conditions.

Free water m³. Deducted only when TOV is selected.

Observed temperature °C.

Reference Density & Volume Correction

Reference property basis

Reference property value kg/m³ at 15°C.

VCF / correction method

Entered CTL / VCF Use the factor generated by the approved current petroleum-measurement procedure.

Observed density kg/m³ at observed conditions; used by density-ratio method.

Volumetric thermal expansion α ×10⁻⁶ /°C; used only for thermal-estimate method.

Sediment & water % of GSV deducted to obtain NSV.

Cargo Reference Properties

Commodity group

Reference property basis

Reference property value kg/m³ at 15°C.

Default thermal expansion α ×10⁻⁶ /°C; planning estimate only.

Global sediment & water % applied after standard-volume correction.

Pressure correction CPL User-entered approved factor. Leave 1.000000 for atmospheric-pressure tank calculations.

API gravity @60°F cross-check Optional entered/certificate value; set blank to skip.

Density @60°F cross-check kg/m³; optional.

Ship/shore difference review limit % absolute difference.

Tank Quantity Register

Each row can use its own correction method. Certified factor is the preferred custody-transfer workflow. Density ratio uses ρobserved/ρreference. Thermal estimate uses a constant user-entered expansion coefficient and is a planning approximation, not ASTM D1250/API MPMS 11.1.

Use	Basis	Observed m³	Free water m³	Temp °C	Method	Entered CTL/VCF	Observed density kg/m³	α ×10⁻⁶/°C

Ship / Shore or B/L Reconciliation

Comparison basis

Reference comparison quantity m³ for NSV basis or metric tonnes for mass basis.

Comparison label

Cargo Measurement Checks

Tank calibration / observed volumes verified Ullage/sounding, trim/list corrections and calibration tables are controlled separately. Free water independently established Free water is deducted before GOV where applicable. Average cargo temperature verified Tank temperatures are representative of the measured volume. Density / API test basis verified Hydrometer/density results are corrected and reported at the stated reference temperature. Current approved VCF procedure used Custody-transfer CTL/CTPL factors come from licensed/current API/ASTM implementation where required. S&W sampling result verified Global sediment/water deduction matches the agreed cargo sample result. Pressure basis reviewed CPL is 1.0 only where pressure correction is not applicable/material. Ship/shore reconciliation reviewed Material differences are investigated before quantity sign-off.

Standards / licensing limitation: ASTM D1250-25 is the current guide for the joint API/ASTM adjunct to API MPMS Chapter 11.1, but the full VCF algorithms and implementation procedures are contained in separately licensed adjuncts/software. This ShipUniverse tool therefore does not reproduce those proprietary algorithms. “Certified factor” means the user supplies CTL/VCF generated by their approved procedure. Density-ratio and thermal-expansion modes are transparent engineering alternatives and must not be mislabeled as ASTM/API table results.

Measurement basis: API gravity is referenced to 60°F and is calculated from relative density 60/60 using API = 141.5/SG − 131.5. Relative density / SG is dimensionless; density fields are always kg/m³. The quantity chain used here is TOV minus free water = GOV, then GOV × temperature/pressure correction = GSV, then GSV × (1 − S&W fraction) = NSV. Mass is calculated from NSV and the entered/derived density at the same reference temperature. NGL/LPG are outside ASTM D1250/API MPMS 11.1 and require the applicable API MPMS Chapter 11.2 procedure.

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