The insulated (non-refrigerated) ISO tank is the standard build for most chemical T11s. Polyurethane foam insulation 50 to 100 mm thick under aluminium or GRP cladding reduces heat ingress on long ocean voyages and prevents thermal-expansion overpressure. There is no active heating or cooling system; the insulation alone holds cargo temperature stable through the transit. Most T11 fleets ship insulated as default; this page covers the dedicated terminology rather than a distinct tank class.
What insulated is built for
Standard chemical and food-grade cargoes that don’t need active heating but benefit from temperature stability through ocean transit. Methanol, MEG, glycerin, alcohols, glycols, and the broad middle of the chemical lane all ride insulated T11 builds. Tropical-route cargoes get more insulation (100 mm vs 50 mm typical) to keep cargo below the IMDG 4.2.1.9.5 reference temperature of 50 deg C without active cooling.
Construction and materials
316L stainless cylinder, 6 mm reference shell, with 50 to 100 mm polyurethane foam (PUR) insulation between cylinder and outer cladding. PUR foam thickness varies by route: 50 mm for short-haul or temperate routes, 75 mm typical, 100 mm for tropical routes or sensitive chemistry. Aluminium cladding is standard; GRP is an alternative for slightly lower tare and easier repair. The cladding protects the insulation from mechanical damage and weather, and provides a paintable surface for fleet branding.
U-value (thermal transmittance) on a fresh 75 mm PUR build runs around 0.3 to 0.4 W per square metre per Kelvin. Older insulation with moisture ingress can degrade to 0.6 W per m2 per K, doubling the heat ingress and shortening the cargo’s safe transit window. Operator maintenance includes periodic insulation surveys; a 10 to 15-year-old tank with original insulation may need re-insulation depending on observed performance.
When insulated is the right choice
Insulated is the right tank for almost every chemical and food-grade cargo. The insulation cost is modest (USD 1,500 to 2,500 incremental on the tank build) and the operational benefit on long ocean voyages is substantial: cargoes stay closer to fill temperature, the IMDG 4.2.1.9.4 fill caps don’t bite as hard, and active heating systems have less work to do.
When insulated is the wrong choice
Insulated is essentially never the wrong choice for chemical T11 service. The dedicated terminology rather than the build itself is what matters: a “non-insulated T11” usually refers to a T50 (gas tank, no insulation by default) or to a specialty H2O2-dedicated T14 build that omits insulation per the operator’s H2O2 spec.
How an insulated booking is verified
Pre-loading inspection covers the standard plate stack plus a visual check of insulation condition (look for damaged cladding, signs of water ingress, moisture stains on the manlid surround). Operator maintenance log shows the insulation survey history. For tropical-route bookings, the insulation thickness should match the route: 100 mm typical for China-Southeast-Asia-Australia; 75 mm acceptable for higher-latitude routes.