How Tank Storage Agreements Work

A tank storage agreement (TSA) sets the commercial and operational terms under which a terminal holds a client's product. Regardless of terminal or region, most agreements are built around the same core elements: which tank or tank group is allocated, the product grade permitted in it, the contract term, the storage capacity reserved, and the fee structure that applies to holding and moving product through that capacity.

What differs between a short spot rental and a multi-year dedicated lease is mostly a matter of degree — how much flexibility the client has to change grade, how strictly capacity is reserved even when unused, and how the fee structure rewards or penalizes actual throughput versus idle storage.

Most agreements separate charges into a few categories. A storage fee is usually quoted per cubic meter per month and covers simply holding the reserved capacity, whether it is full or not. A throughput fee (sometimes called a handling fee) is charged per ton or per cubic meter actually moved in or out of the tank — so an active trading position with frequent injections and withdrawals costs more in throughput than a static one, even at the same storage volume.

On top of these two baseline charges, agreements typically itemize ancillary services separately: heating to keep viscous products like heavy fuel oil workable, nitrogen blanketing for oxidation-sensitive products, blending, additional gauging or sampling requests, and any non-standard handling. Clients who only need straightforward storage and standard loading/discharge should expect a simpler fee schedule; those requiring heating, blending or frequent quality testing will see it itemized and charged as used.

Many tank storage agreements include a minimum stock — sometimes called a heel — requirement. This is a floor quantity the client must maintain in the tank at all times, typically to keep pumps primed, prevent product from settling below suction lines, or maintain quality (some products degrade faster once exposed to more tank headspace and temperature swings). The heel is not usable inventory from the client's perspective; it is effectively locked working stock the terminal requires to keep the tank operable.

Agreements state the heel as either a fixed volume or a percentage of total tank capacity, and specify what happens if the client draws below it — usually a notice requirement to top up within a defined period, sometimes with a penalty charge attached.

A TSA sets out how the client requests product movements. Standard practice is a nomination process: the client submits a notice ahead of a planned injection (receiving product into the tank, typically from a vessel or pipeline) or withdrawal (loading product out, to a vessel, barge, or road tanker), specifying volume, timing, and the vessel or transport details where relevant.

Notice periods vary by terminal and by mode of transport — vessel nominations generally require more lead time than road tanker loadings, given berth scheduling. Agreements also typically define what happens to unused notice slots, and whether last-minute changes carry a rescheduling fee.

A TSA will define the terminal's responsibility for product quality while in storage, and where that responsibility starts and ends — typically at the point of custody transfer, verified by gauging on receipt and delivery. It will also set an allowable loss tolerance to account for the normal, expected evaporation and measurement variance inherent in bulk liquid handling, beyond which the terminal may be liable and below which loss is treated as a standard operational allowance rather than a claim.

For products handled under specific quality standards — EN 590 diesel or Jet A1 aviation fuel, for example — the agreement will typically reference the applicable specification and set out the testing regime used to confirm the product still meets it on withdrawal.

Spot storage arrangements run for weeks to a few months and suit a single cargo position or a short trading strategy — they carry a higher per-unit storage rate in exchange for flexibility and no long-term commitment. Term leases run from six months to multiple years, reserve dedicated capacity, and generally price more favorably per cubic meter in exchange for the client committing to occupy that capacity (and pay for it) regardless of whether it is fully used month to month.

The right structure depends entirely on the client's trading pattern. A trader taking opportunistic positions on price moves usually wants spot flexibility even at a premium; an operator running a consistent supply chain — say, feeding diesel into a regional distribution network — is usually better served locking in dedicated term capacity at the lower rate.

Before committing to a tank storage agreement, it is worth getting clear, written answers on: the exact fee schedule including all ancillary charges, the heel requirement and its penalty terms, nomination lead times for your typical mode of transport, the allowable loss tolerance, and what happens at contract end if you have not fully withdrawn your stock. Our commercial team at Unlimited Logistics B.V. structures agreements at our Rotterdam terminal — and across our subleased network in Houston, Jurong, Fujairah and Ningbo-Zhoushan — around exactly these terms, and can walk through a draft agreement line by line before you commit.