A pressure vessel dressed as a shipping container
The world’s fleet of tank containers stood at 882,023 units on 1 January 2025 — up 3.96% on the year, after manufacturers built 42,123 new tanks in 2024, according to the International Tank Container Organisation (ITCO). Each one is the same idea executed with minor variations: a cylindrical stainless-steel pressure vessel mounted inside a standard 20-foot ISO frame, 6,058 mm long, 2,438 mm wide and 2,591 mm tall. Because the frame matches a standard dry container’s corner castings, an ISO tank rides the same ships, cranes, trains and trailers as every other box — which is the entire point. Bulk liquid chemistry gets the economics of containerisation without drums, flexitanks or a dedicated parcel tanker.
What a T11 actually is
Tank types are coded under the UN portable-tank system, and the workhorse is the T11. A typical T11 holds 21,000 to 26,000 litres, with a maximum allowable working pressure of 4.0 bar and a test pressure of 6.0 bar; most carry rock-wool insulation under GRP cladding and steam or glycol heating channels, so a cargo that solidifies at ambient temperature can be re-melted for discharge. A T11 is approved for a wide range of hazardous and non-hazardous liquids — acids, solvents, food-grade oils, even wine and spirits — while higher-numbered types (T14, T20, T22) take progressively more aggressive cargoes at higher pressures. One tank, properly cleaned, can carry a hazardous solvent one voyage and an edible oil the next — though food-grade operators often dedicate tanks to avoid exactly that history.
Why chemical logistics chose the box
Against drums, the arithmetic is brutal: a single T11 replaces roughly a hundred 200-litre drums, with no filling losses across hundreds of packages, no pallets and far less labour at each end. Against flexitanks — single-use plastic bladders inside a dry container — the tank wins on hazardous cargo, which flexitanks generally cannot carry at all, and on reusability: a steel tank is refilled voyage after voyage where a bladder is scrapped after one. The tank is a sealed system from filling to discharge, which matters when the cargo is toxic, flammable or worth more per litre than the freight. That is why the fleet keeps growing — a net 33,623 tanks added in 2024 — even as new production cooled from 56,600 units in 2023 to 42,123 in 2024.
Singapore sits at the centre of the trade twice over
Singapore matters to the tank container industry for two structural reasons. First, cargo: Jurong Island hosts more than 100 energy and chemicals companies with over S$50 billion invested, per the Economic Development Board, and the sector generates more than a fifth of Singapore’s manufacturing output — a constant source of speciality chemicals that suit tanks rather than parcel tankers. Second, connectivity: the port handled a record 44.66 million TEUs in 2025, up 8.6%, and a tank container is, to a terminal, just another TEU. A tank of Jurong Island solvent can reach any port a container ship serves.
The industry’s own geography confirms it. ITCO’s 2025 report lists Singapore-headquartered firms among the trade’s significant players — lessors Seaco Global (43,000 tanks) and Raffles Lease (35,000) and operator Eagletainer (13,500) — alongside global operators such as EXSIF Worldwide (71,300) and Stolt Tank Containers (52,200).
Cleaning and depots: the exacting half of the business
A tank is only as good as its last cleaning certificate. Between cargoes, tanks pass through depots for interior washing — hot water, caustic or detergent cycles depending on the previous cargo — plus heating-system tests, valve and gasket checks, and the periodic statutory inspections the portable-tank rules require. The cleaning record travels with the tank, because a residue measured in parts per million can ruin a food-grade or electronic-grade load. Singapore’s depot cluster serves the port and Jurong Island traffic, though no authoritative public count of local depots exists — an honest gap in an otherwise well-documented industry.
Where the record connects
Tanks are the moving half of a system whose fixed half is storage. On the Singapore Industry Index record, Vopak Terminals Singapore anchors the independent tank-storage trade across Jurong Island, Banyan, Sebarok and Penjuru; Advario Singapore runs the Helios terminal and chemical storage on Jurong Island; Stolthaven Singapore — part of the Stolt-Nielsen group, whose tank container arm is among the world’s largest operators — runs 81 tanks totalling 230,700 m³ at Tembusu; and Jurong Port Tank Terminals adds around 580,000 m³ with berths to 180,000 DWT. On the forwarding side, Halcon Primo Logistics handles dangerous-goods and oil-and-gas project cargo from its owned Jurong hub. The companies that fill, store and move Singapore’s chemistry are, increasingly, on the record.