T14 is the high-hazard liquid portable tank. Min test pressure 6 bar, MAWP 4 bar, 6 mm reference-steel shell (4.18 mm in 316L per IMDG 6.7.2.4), NO bottom outlet (top discharge through a dip-pipe only), pressure-relief regime is a frangible bursting disc plus a tell-tale gauge that signals disc rupture, with the spring-loaded PRV set 10% above test pressure at 4.4 bar. T14 is mandatory for PG I corrosives and Class 6.1 PG I/II toxics that the IMDG Code Chapter 6.7 will not authorise in T11. The defining cargo is 98% sulphuric acid (UN 1830).
What T14 is built for
PG I corrosives, the high-hazard end of Class 6.1, and Class 3 PG I flammables that cannot ride T11. Common cargoes: 92 to 98% sulphuric acid (UN 1830), fuming sulphuric acid / oleum (UN 1831), 70 to 90% nitric acid (UN 2031), red fuming nitric (UN 2032), 48 to 70% hydrofluoric acid in lined builds (UN 1790), 10 to 15% sodium hypochlorite in lined builds (UN 1791), concentrated 35% hydrochloric acid in lined builds (UN 1789), 30 to 60% hydrogen peroxide in dedicated builds (UN 2014), dimethyl sulfate (UN 1078), TDI (UN 2078). The H2O2-dedicated T14 is non-insulated, has no steam heating, and carries a 10 inch rupture disc plus a high-capacity PRV with oxygen-compatible PTFE seals. It is never reused for any other cargo.
Construction and materials
Two distinct construction routes, picked by the chemistry. Route one: full 316L stainless cylinder, suitable for 92 to 98% sulphuric acid and oleum (these passivate stainless steel above 70%), nitric acid 70%, and TDI. Route two: carbon-steel shell with a chemical-resistant lining, suitable for cargoes that attack stainless steel. The lining catalogue runs from 16 to 20 mm rotomoulded LDPE for hydrochloric acid 35% and 50% caustic soda, through 2 to 5 mm PTFE / FEP / PFA sheet for hydrofluoric acid 70% and concentrated bases at 120 deg C, through soft natural rubber and bromobutyl rubber for dilute mineral acids, through legacy lead lining for concentrated sulphuric. Lining thickness reduces effective volume by 8 to 15%, which is one reason a T14 typical capacity (around 21,000 L) sits below T11 (around 24,000 L).
The frangible-disc-plus-tell-tale-gauge regime is a defining feature. The disc is a metal foil sized 6, 8, or 10 inches, mounted in series with the PRV. If the tank over-pressurises catastrophically the disc ruptures and the PRV vents through it; the tell-tale gauge alongside the disc shows whether the disc has fired, so a port surveyor can detect a previous over-pressure event during the 2.5-year intermediate inspection. Top discharge is via a dip-pipe rather than a foot valve, so there is no bottom-outlet failure mode under fire conditions or vehicle rollover.
When T14 is the right choice
T14 is the right tank when IMDG DGL Column 13 assigns T14 (or any weaker code that the substitution rule of IMDG 4.2.5.2.5 allows up into the T14 envelope). It is the right tank when the cargo’s metallurgy compatibility profile matches either bare 316L or one of the standard lining systems. It is the right tank for dense PG I/II liquids where the smaller typical capacity (around 21,000 L vs T11’s 24,000 L) places the weight-limited fill above the IMDG 80% surge floor. For 98% sulphuric (SG 1.84) the math: weight cap = (36,000 minus 4,200) / 1.84 = 17,283 L = 82.3% fill in a 21,000 L T14, which clears the surge floor cleanly. The same cargo in a 24,000 L T11 lands at 72.5% fill and fails the 20% to 80% surge band.
When T14 is the wrong choice
T14 is the wrong tank for the highest-hazard organometallics, fluorination products, and toxic-by-inhalation Hazard Zone A/B substances. Bromine (UN 1744) requires T20 with 8 mm reference-steel shell and lead lining. TEAL (triethylaluminium UN 3394) and similar pyrophorics require T21 with 10 mm shell. Highest-hazard toxics-by-inhalation require T22 with 10 mm shell, frangible disc, and ASME U-stamp mandatory under 49 CFR 178.275. T14 is also the wrong tank for liquefied gases (T50) and cryogenics (T75), which are family-specific and do not participate in the T1 to T22 substitution rule.
A specific failure mode
A receiver in Sydney books a T14 stainless tank for 22 tonnes of 35% hydrochloric acid (UN 1789). The tank ships, and the cargo arrives off-spec on iron content with visible discolouration. Investigation: the operator supplied a stainless T14 because the booking did not specify a lining, and 316L stainless reacts with concentrated HCl at room temperature. The fix on the next booking: specify “T14 PE-lined” or “T14 PTFE-lined” explicitly in the booking confirmation, and require the operator’s certificate of build conformity before tank assignment. Concentrated HCl at any common shipping concentration (32%, 35%, 37%) attacks bare stainless. The right China-Australia equipment is a T11 PE-lined tank with a 16 to 20 mm LDPE / LLDPE rotomoulded liner, not a stainless T14.
How to verify a T14 booking
Pre-loading inspection covers the same plate stack as T11 (CSC within 30 months, 5-year hydraulic, 2.5-year intermediate, EFTCO cleaning document) plus the lining condition where the build is lined. Lined-tank inspection includes a visual walk-through of the manlid, a sniff test for prior cargo, sometimes a spark test for pinholes in PTFE or PE liners, and a check of the lining manufacturer’s certificate (Marflex, AGRU, Blair Rubber, or equivalent). For H2O2-dedicated builds the operator must produce evidence that the tank has not carried any other cargo since its last clean. Surveyors: SGS, Bureau Veritas, Intertek.