A concentrate shipment is valued on an assay. The tonnage is known, the moisture is measured, and the payable value falls out of the metal content that two laboratories independently determine. When those two determinations agree, settlement is mechanical. When they do not, a short clause buried in the sales contract decides how much money changes hands.
That clause is usually well drafted. Concentrate sales contracts have a long lineage and the assay provisions have been refined across decades of trade. What is rarely managed is the set of dated duties the clause creates, which run on tight timetables and are frequently handled over email by two or three individuals who happen to know the routine.
The exposure is not hypothetical. A missed exchange deadline can bind a seller to a buyer's number on a shipment worth millions, and the remedy is usually nothing at all, because the contract says what it says. Treating each shipment as a small obligation set with its own clock is the fix, and it is the same discipline that keeps mining royalty obligations from drifting.
The obligations a single shipment creates
Reading the sampling and assay articles against an actual cargo produces five dated duties. Each has a trigger, a deadline and a consequence for lapse, and in most contracts the consequence is not a damages claim but a silent loss of a right.
- Sampling attendance, where each party has the right to attend or appoint a representative, exercisable within a notice period before the sampling event.
- Sample preparation and sealing, producing the parties' portions and the sealed reserve, with a defined protocol and retention period.
- Exchange of assays, requiring simultaneous exchange of results by a deadline counted from sampling, discharge or receipt depending on the contract.
- Splitting limit test, applying the per-element tolerance to decide whether the mean settles the figure or the umpire process begins.
- Umpire nomination and submission, with its own short window for nominating from the agreed list and despatching the reserve sample.
Of these, exchange is the pressure point. The deadline is typically short, it is counted from an event that happens at a port rather than in an office, and the trigger date is often recorded only on a surveyor's report that reaches the commercial team days later. A shipment can therefore consume half its exchange window before anyone internally knows the clock has started. In a busy shipping season, with several cargoes moving at once and surveyor reports arriving out of order, the position is worse still, because the team is reconstructing which clock belongs to which parcel from attachments.
Deadlines counted from sampling or discharge begin when the event occurs, not when the report arrives. Capture the event date from the surveyor feed and derive the deadline from it, so the window is visible from day one rather than from the day the paperwork lands.
Drafting choices that decide how disputes resolve
Within a conventional structure there is real variation, and the differences change outcomes in money rather than in principle. A commercial team that has never compared its own assay articles against two or three counterparty templates is usually working with terms inherited from whichever contract was signed first. Five choices are worth reviewing before the next contract is signed.
- Per-element splitting limits. A single tolerance across the whole certificate under-protects the payable metal and over-triggers on trace elements.
- Umpire averaging rule. Whether the umpire figure settles outright, or is averaged with the nearer party result, materially changes the expected outcome.
- Umpire list and selection order. A named list with a rotation or alternating nomination removes a second dispute at the worst moment.
- Cost allocation and cap. Loser-pays with a stated cap per determination keeps the incentive honest without inviting cost arguments.
- Reserve retention period. The retention window has to outlast the realistic dispute cycle, including provisional and final invoicing.
A five-step control roadmap
Step 1, Build a per-shipment obligation template
Create a standard set of obligation records that is instantiated for every cargo, with the five duties above and their deadlines derived from contract parameters. The template is written once per contract and reused for every shipment under it.
Step 2, Feed event dates from the surveyor
Connect or import the surveyor's sampling and discharge dates so deadlines calculate automatically. Manual entry of the trigger date is the most common cause of a window that opens late, and it is entirely avoidable.
Step 3, Record splitting limits as contract data
Store per-element tolerances as structured fields rather than leaving them in the contract text. The comparison between the two certificates then becomes a calculation rather than a reading exercise performed under time pressure.
Step 4, Maintain the umpire list annually
Review the named laboratories once a year for accreditation status, capacity and independence from both parties. A list that has not been reviewed since the contract was signed frequently includes a laboratory that can no longer act.
Step 5, Track reserve sample retention
Record the retention expiry for each reserve sample and alert before it lapses, especially where provisional invoicing means the final settlement is still months away. Losing the reserve removes the only agreed route to resolution.
Give every cargo its own obligation set
Deadlines derived from surveyor events, with splitting limits and umpire steps held as data.
Where the commercial loss actually occurs
Disputed assays are visible and get attention. The larger, quieter loss is in shipments where the difference sits just inside the splitting limit and the mean is accepted without review. Across a year of cargoes a persistent bias in one direction is worth more than any single dispute, and it is only detectable if the paired results are retained as data rather than filed as certificates. A simple scatter of own result against counterparty result, by element and by destination, answers the question in minutes once the data exists, and cannot be produced at all when the certificates sit in a document folder. Keeping the two figures, the mean and the umpire outcome where one occurred on a single record makes that trend analysis possible, in the same way that retained rate and ticket data exposes margin leakage in oilfield service rate schedules.
Shipment obligations and their clocks
The table sets out a representative duty set. Windows vary widely by contract and commodity and should be read from the governing sales agreement rather than assumed.
| Obligation | Trigger | Typical window | Consequence of lapse |
|---|---|---|---|
| Notice of intention to attend sampling | Nomination of vessel or arrival notice | Days before sampling | Right to attend is lost |
| Exchange of assay certificates | Sampling or discharge completion | Weeks, contract specific | Other party result may bind |
| Declaration of splitting limit breach | Receipt of exchanged results | Short, often days | Mean settles by default |
| Umpire nomination and despatch | Declaration of dispute | Short, often days | Dispute route closes |
| Reserve sample retention | Sample preparation | Months, contract specific | Umpire process becomes impossible |
None of this is new to a commercial team that has shipped concentrate for years. What changes when the duties are tracked is that the knowledge stops being personal. The clock runs whether or not the one person who remembers the routine is on leave, and the clause works the way it was drafted to work rather than the way the last few shipments happened to go. That matters most in the periods when it is hardest to maintain, which are the months when volumes are high and the commercial team is shortest of time.
For related guidance, see The operator’s guide to oilfield master service agreements, Contractor prequalification and MSA control for operators and Decommissioning and abandonment obligation tracking.
