The lead-lined ISO tank is the legacy build for concentrated sulphuric acid 78 to 98% (UN 1830). 3 to 6 mm lead lining inside a carbon-steel shell, vulcanised in place during manufacture or applied as a chemically bonded sheet. Lead has been the historical solution for concentrated sulphuric: corrosion-resistant indefinitely, mechanically tough, dimensionally stable. The lining is also the build’s defining problem: at SG 11.3 the lead adds 1,500 to 2,000 kg of tare versus a stainless or PTFE-lined equivalent, and end-of-life disposal triggers a hazardous-materials process with substantial cost and regulatory complexity. New orders favour PTFE-lined or bare 316L stainless. The existing lead-lined fleet is gradually retiring.
What lead-lined is built for
Concentrated sulphuric acid 78 to 98% (UN 1830, Class 8 PG II) on long-rotation legacy fleets. Bromine (UN 1744) in dedicated T20 lead-lined builds remains the canonical bromine cargo because no other lining material survives bromine’s reactivity profile at acceptable cost. The bromine fleet is the smallest niche of the lead-lined family but the one where the chemistry continues to justify the lining despite the disposal issues.
Construction and materials
Carbon-steel Q345R shell, typically 6 mm thick, with a 3 to 6 mm lead lining. The lead is applied via two methods: vulcanised onto a rubber substrate inside the shell (older builds), or chemically bonded directly to the steel via a lead-tin alloy intermediate layer (newer builds). The seam at the manlid and outlet uses lead-soldered joints with PTFE-gasketed compression fittings.
Tare runs 6,300 to 6,800 kg on the T14 sulphuric build (6 mm shell), around 1,500 to 2,000 kg above an equivalent stainless or PTFE-lined T14. The T20 bromine build runs heavier still: 8 mm reference-steel shell plus the lead lining pushes tare to 8,000 to 9,500 kg. Shell volume on either build runs 16,000 to 20,000 L (around 18,000 L typical) because the lining occupies internal volume. The combined tare and capacity penalty cuts payload by 2 to 3 tonnes versus an unlined T14 stainless on the sulphuric build, and on the T20 bromine build the SG 3.10 cargo density caps the practical fill at around 8,000 to 9,000 L of bromine well below the shell volume.
When lead-lined is the right choice
Lead-lined is the right tank for legacy fleet rotations on concentrated sulphuric where the existing equipment has years of service life remaining and where the operator-receiver supply chain is built around it. New bookings rarely justify a new-build lead-lined tank; the trend is toward PTFE-lined builds for new sulphuric service. For bromine specifically the lead-lined T20 remains the standard.
When lead-lined is the wrong choice
Lead-lined is the wrong tank for any new build on sulphuric service. PTFE-lined T14 or bare 316L stainless deliver equivalent corrosion resistance at lower tare and without the end-of-life disposal complexity. Lead-lined is also the wrong choice for cargoes outside the narrow concentrated-sulphuric and bromine niches; the lining is over-engineered for most chemistry and the weight penalty is dead weight.
How a lead-lined booking is verified
Pre-loading inspection covers the standard lined-tank plate stack plus a lead-lining condition check. The inspector looks for blistering of the lining (lead corrodes slowly under specific conditions), seam integrity at the manlid and outlet, and signs of wear or thinning at high-flow points. The operator’s lining-service history is critical: a 15 to 20-year-old lead-lined tank with documented annual lining inspections is normal; an older tank with sparse history is a flag because the disposal liability transfers to whoever takes the next booking.