Specialised Products

Tank coating compatibility. Coating choice is the first and most consequential filter. Stainless steel (typically 316L) is the most chemically resistant surface available and the only realistic option for strong caustics, concentrated acids, very high-purity methanol, and aggressive intermediates. It is also the most expensive to build and operate, and stainless tonnage trades at a premium. Epoxy phenolic coatings sit in the workhorse middle of the market: cost-efficient, broadly compatible with most organic chemicals, vegetable oils, base oils, biodiesel, and many mild acids at moderate temperatures, but not appropriate for strong caustic, concentrated acids, or some aromatic-heavy grades. Zinc silicate is excellent for many solvents, aromatics, and clean petroleum products, but is reactive with low-pH cargoes and incompatible with caustic soda. Before fixing, we read the vessel’s coating certificate, request the last three cargoes per tank, and where the grade demands it, we will require a coating inspection prior to load. That can include FSIV (Final Stage In-tank Verification) testing, wall-wash by surveyors using ASTM methods, holiday detection on epoxy coatings, and dry-film thickness measurements where coating degradation is suspected. Coatings absorb previous cargoes (styrene into epoxy is a well-known offender), and that absorption can taint a sensitive next cargo even after a textbook clean. We flag this before the offer goes in, not after a discharge dispute.

IMO classification. Chemical tankers are classified IMO I (most hazardous), II, or III under the IBC Code, and now that we have bridged into IMO terminology the classifications correspond to IBC Code Type 1, Type 2, and Type 3 ships. In practice, IMO I tonnage handles the most dangerous cargoes (propylene oxide, certain organic peroxides, a small set of high-hazard intermediates) and is the smallest and most heavily regulated fleet. IMO II covers the bulk of the chemical trade: caustic soda, sulphuric and phosphoric acids, methanol, MEG, glycols, styrene, and most of the high-volume organic chemicals. IMO III is the lower-hazard tier, used for vegetable oils, lubricant base oils, biodiesel feedstocks, and milder products. Every chemical tanker must carry a valid Certificate of Fitness specifying which cargoes she is approved to lift; we verify that the cargo in question is listed on the CoF before nominating the vessel.

Cargo segregation. Modern parcel tankers are built to carry anywhere from four to forty-plus segregated grades on a single voyage, with dedicated pumps, lines, cofferdams, and segregation valves between tank groups. The discipline is mostly about what cannot share a vessel at all: strong oxidisers stowed near organic products, moisture-sensitive cargoes (isocyanates, certain anhydrides) loaded into a tank whose previous cargo or neighbour holds residual water, low-flash solvents adjacent to incompatible vapour spaces. We work the stowage plan against the cargo compatibility matrix before nomination, not as an afterthought, and we read cofferdam and valve arrangements off the vessel’s GA before committing to a multi-grade fixture.

Heating, temperature control, cleaning. Many specialised cargoes have minimum carriage temperatures and active heating obligations. Palm oil and palm olein typically travel at 50-55°C, heavy residual fuel at 50-60°C, caustic soda 50% at around 15°C minimum to avoid crystallisation, certain waxy bio-feedstocks well above ambient. Heating coils must be in good order and free of leaks. For high-purity grades, methanol IMPCA spec being the canonical example, wall-wash testing by an independent surveyor is non-negotiable, and the cleaning regime between cargoes is dictated by the difference between previous and next cargo. Sometimes that is a hot wash with detergent and steam, sometimes butterworth-only, sometimes a full crude wash and recoat inspection. We agree the cleaning standard, who pays for it, and what counts as acceptance into the charter party before signing.