Standard 20ft Intermodal Pressure Vessel
An ISO tank container is a heavy-duty stainless steel pressure vessel mounted securely within an external 20-foot structural frame conforming to international ISO dimensions (ISO 668 and ISO 1496-3).
This standardized construction permits seamless intermodal carriage across global container vessels, electric rail networks, and heavy road chassis without any intermediate transfer of the liquid cargo.
A single standard ISO tank container can transport up to 26,000 litres—carrying up to 66% more product than a standard 20-foot dry container filled with 78 drums of the same compound (and even greater with UCL's 32,500L Jumbo Square containers). This substantially decreases ocean freight costs per unit volume while ensuring hermetic containment throughout voyage transit.
Anatomy of a UCL 25,000L T11 ISO Tank Container
1. 316L Stainless Steel Vessel
Fabricated from heavy-gauge austenitic 316L stainless steel, cold-rolled and pickled/passivated for superior chemical resistance and food-grade hygiene.
2. ISO Structural Framework
High-tensile carbon steel frame with standard ISO corner castings, tested to withstand 9-high stacking under full 36,000 kg gross weight rating.
3. Triple Closure Bottom Discharge
Features internal footvalve, external secondary valve, and 3" BSP outlet cap/blanking flange. All 3 closures must fail before any leak can occur.
4. Top Manlid & Inspection Hatch
500mm diameter swing-bolt manlid with food-grade PTFE/encapsulated silicone gasket for internal inspection, sampling, and steam cleaning.
5. Safety Relief Valve (SRV)
Calibrated spring-loaded pressure relief valve with bursting disc and pressure telltale gauge, safeguarding against thermal expansion spikes.
6. Steam Heating System & Insulation
External longitudinal steam jackets rated to 4 bar working pressure, wrapped in 50mm thermal insulation and protective weather sheeting.
Technical Equipment Specifications (Typical T11 & Jumbo Fleet)
| External Frame Dimensions | 20ft Length × 8ft Width × 8ft 6in Height (6,058mm × 2,438mm × 2,591mm) • Standard ISO Dimensions |
| Vessel Barrel Material | 316 / 316L Austenitic Stainless Steel (Cold-rolled, pickled & passivated or mirror-polished Ra < 0.4 µm) |
| Nominal Shell Capacity | 21,000 to 26,000 Litres (standard cylindrical) • Up to 32,500 Litres (Jumbo Square Tank) |
| Maximum Gross Weight (MGW) | Standard ISO rating: 36,000 kg (79,366 lbs) |
| Average Tare Weight | Approx. 3,600 kg to 4,200 kg (depending on insulation, baffle plates, and valves) |
| Maximum Cargo Net Payload | Up to 32,200 kg (subject to localized road transport axle weight limits) |
| Working & Test Pressure | Working Pressure: 4.0 bar (58 psi) • Hydrostatic Test Pressure: 6.0 bar (87 psi) |
| Safety Closure Redundancy | 3 mandatory independent closures on bottom outlet (Internal Footvalve, Butterfly/Ball valve, 3" BSP cap) |
| Thermal Management | Pre-installed longitudinal steam jackets (max 4 bar); optional hot water channels, electric heating cables, or PU insulation |
| Regulatory Approvals | UN Portable Tank (T11 / T14 / T75), IMO Type 1, ADR/RID, US DOT, IMDG, ISO 1496-3, CSC Convention |