Incoterms for Sulfuric Acid: FOB, CIF and DAP Compared for Buyers

Bulk sulfuric acid purchasing is as much a transfer of custody under the ICC Incoterms rules as a specification exercise in total acidity, density, and iron content. In concentrated form, commercial acid typically moves at 93.2 % or 98 % H₂SO₄, with a density of approximately 1.836 g/cm³ at 20 °C for the higher grade. The selected term—FOB, CIF, or DAP—sets the survey point, the insurance obligation, and the moment a leaking ISO tank container ceases to be the seller’s problem. Buyers comparing Incoterms for Sulfuric Acid: FOB, CIF and DAP must therefore evaluate more than freight cost; they must map the point where chemical risk, regulatory documentation, and discharge demurrage transfer.

Because concentrated sulfuric acid is classed as UN 1830, Class 8, packing group II when strength exceeds 51 %, the mode of carriage is not free-form. Ocean and road carriers impose segregation from alkaline compounds such as UN 1824 sodium hydroxide solution, prohibit unlined steel containers for dilute grades, and require a shipper’s dangerous goods declaration and a safety data sheet conforming to GHS. Within this framework, the Incoterms selection does not remove the dangerous goods obligations of either party; it assigns the operational interface at which each party acts.

How Do FOB, CIF and DAP Relocate Risk and Control in Bulk Acid Shipments?

Under Incoterms 2020, FOB obliges the seller to clear the acid for export and place it on board the vessel nominated by the buyer at the named port of shipment. Risk transfers when the product is on board; the buyer pays ocean freight and any marine cargo insurance. This term gives the buyer control over carrier selection and route, but also exposes the buyer to additional costs if the nominated vessel is delayed and the terminal holds a loaded truck or ISO tank at the port. The buyer’s load-port surveyor is the first independent party to verify mass, density, and tank lining condition.

CIF moves the freight contract and minimum insurance to the seller, but the risk transfer point remains at the loading port. The seller pays cost, insurance and freight to the named destination port, not discharge. The default insurance required under Incoterms 2020 for CIF is Institute Cargo Clauses ICC(C); this cover responds to defined perils such as fire, collision, stranding, and discharge of cargo at a port of distress, but may not respond to a slow shell leak or contamination caused by ordinary sea conditions. A buyer receiving only ICC(C) cover should request an upgrade to ICC(A) or a named-peril extension for leakage and contamination if the cargo is to be accepted solely on the strength of the seller’s insurance certificate.

DAP imposes the widest seller logistics obligation among the three terms. The seller delivers when the goods are placed at the disposal of the buyer on the arriving means of transport at the named place, ready for unloading. The buyer unloads, clears import formalities, and pays duty. For sulfuric acid, DAP commonly places the named place at the buyer’s tank farm flange; the buyer is responsible for connecting the unloading hose, operating the acid pump, and providing secondary containment.

One consequence of the differing risk transfer points is that under FOB a buyer may reject a tank container at the load port for a failed shell inspection, whereas under CIF the same defect may not be discovered until discharge. CIF buyers should require a copy of the tank container periodic inspection certificate under ISO 1496-3 before departure; FOB buyers can request the same certificate but have a direct opportunity to stop loading before the cargo enters maritime custody.

Sulfuric Acid Quality Assurance at the Incoterms Inspection Boundary

Sampling a liquid whose water absorption from humid air can shift the top-surface concentration requires closed-loop samplers, purged sample bombs, and immediate closure of sample ports. At 60 % relative humidity, a small open container of concentrated acid may take up sufficient moisture to alter the surface density within minutes, which means grab sampling without a sealing system is not suitable for contract arbitration.

Concentrated acid at 98 % has a nominal density of 1.836 g/cm³ at 20 °C, but the measurable density in a hot tank truck after a summer road journey may be lower because of thermal expansion. The certificate of analysis should therefore report density corrected to 20 °C or total acidity by alkalimetric titration. Standard methods include ASTM E223 for routine Baumé gravity, total acidity, and iron, and ISO 910 for total acidity in sulphuric acid and oleum for industrial use.

For import into the EU, sulphuric acid is a classified hazardous substance under CLP; the safety data sheet must follow Regulation (EC) No 1272/2008 Annex II, and importers must assess obligations under REACH 1907/2006. A CIF or DAP buyer does not transfer this obligation to the seller because regulatory import responsibility remains a function of entity status, not freight terms. The buyer should request the REACH registration number, extended SDS, and poison centre notification confirmation where applicable before the cargo is moved.

Port storage and passivation of carbon steel are relevant to every Incoterms choice because the term controls who holds inventory during the sea leg. Concentrated acid at ambient temperature can be stored in sound carbon steel tanks because a ferrous sulphate passivation layer forms; dilute acid and high-velocity piping require lined or acid-resistant systems. Any system receiving concentrated acid must be dry and free of residual water because dilution generates a localized exotherm that can exceed 100 °C and create violent steam generation. At the customer’s tank connection under DAP, the unloading pump should be a sealless magnetic-drive or mechanically sealed centrifugal pump rated for acid, typically discharging at 1.5 bar to 2.0 bar against a transfer rate of 20–30 m³/h.

When a DAP Term Outperforms FOB for Small-Capacity Buyers

An acid consumer receiving 10,000 L to 25,000 L per month and operating a single receiving tank may benefit from DAP because the supplier engages the carrier and manages the dangerous goods documentation through the regional border. The buyer’s operational scope is narrowed to a pre-delivery tank inspection, unloading connection, and import clearance. This term is not without cost: the seller’s freight and handling may carry a margin, and the buyer must still provide a safe area for unloading and spill containment in accordance with local secondary containment regulations.

DAP does not solve import clearance. The buyer remains the importer of record and must arrange any customs declaration, duty payment, and domestic hazard notification. If the named place is a terminal tank instead of the buyer’s own flange, the buyer should specify whether the seller includes the terminal access fee and whether the DAP delivery point is before or after the terminal’s custody transfer meter.

Custody transfer meters for sulfuric acid are usually magnetic flow meters or Coriolis mass meters; Coriolis is preferred because it provides simultaneous density and temperature correction. The contractual reference density must be fixed, often 20 °C, so that volume readings are corrected to mass before acceptance. A delivery ticket expressed only in litres may shift the true mass balance when the product temperature differs from the contract reference.

Demurrage Is Not a Trade Term, but It Follows the Buyer Under FOB and CIF

Port and terminal demurrage is charged when a truck, rail tank car, or ISO tank container is held beyond its free time. Under FOB, if the buyer’s nominated vessel arrives late, the terminal may charge storage on the loaded export unit; under CIF, the buyer pays unloading at the destination and can be charged demurrage there if the receiving tank lacks ullage. Under DAP, the seller bears transport until the goods are ready for unloading, but after the vehicle enters the buyer’s site and passes the designated delivery point, any detention caused by a slow pump or unavailable operator commonly becomes the buyer’s charge.

Contracts should fix the free unloading window—2–4 h is commonly applied for a 20,000 L road tanker—and the demurrage rate per hour or fraction. The buyer should also require the seller to coordinate the delivery slot no earlier than 24 h before the receiving tank has sufficient ullage and the analytical sample point is prepared. Failure to align these operational events can shift the commercial advantage of DAP or CIF into a demurrage loss at the discharge flange.

Under FOB, the buyer’s carrier selection should be conditioned on the vessel’s dangerous goods stowage plan. Sulfuric acid in an ISO tank container may be stowed on deck or under deck depending on the line; it must be segregated from Class 8 alkalis and Class 5.1 oxidizers. The buyer should not accept a parcel that is not segregated from foodstuff containers because a leak could contaminate a container stack and create a general average claim.

Under CIF, the bill of lading should carry the onboard notation and the port of discharge exactly as agreed. A buyer that takes delivery of the documents before a pre-shipment sample is taken may lose the ability to dispute quality if the certificate of analysis is merely a seller-furnished specification. Independent surveyor clauses should be written into the sale contract, not left to the insurance policy.

At a receiving terminal fitted with a closed carbon steel tank, a CIF delivery may sample at the ship’s rail, but a DAP delivery is sampled at the truck hose connection. The buyer should take a discharge composite from the top, middle, and bottom of the road tanker if the product has been in transit for more than 6 h, because density stratification in concentrated acid is improbable but temperature stratification after a cold night is possible. The sample loop should be purged with product before final collection and the retained sample held under a desiccator seal.