Appoint an independent surveyor to draw representative samples while the cargo is loaded, split them into sealed sets, and send one set to an accredited laboratory for moisture and purity tests. Quantity is confirmed separately, by draft survey for bulk or by weighbridge for containers.
Checks at loading matter because moisture and grade can change between the stockpile and the ship. A sample taken weeks earlier tells you little about what actually sails.
Agree the rules first
Testing only works if the contract says how it will be done. Before loading, agree these points in writing:
- The moisture and purity limits, and whether each figure is on a dry or as-received basis.
- The sampling standard or method, including how many increments per tonne or per lot.
- The test methods for each property, such as oven drying at a stated temperature for moisture.
- Who appoints the surveyor and laboratory, and whose results are final.
- How samples are sealed, shared and kept, and for how long.
Sampling during loading
For bulk cargo, the surveyor takes small increments at regular intervals from the conveyor or grab, across the whole loading period. These are combined into a composite sample for each lot or hold. For bagged cargo, the surveyor samples a set number of bags chosen at random from different parts of the lot.
The composite is mixed, reduced and split into identical sets. One goes to the laboratory, one to the seller, one to you, and one is kept as a retention sample. Each is sealed and labelled with the lot, date and seal number. Our article on drawing a chemical sample correctly explains the principles.
Moisture checks for bulk cargo
For some fine, moist bulk minerals, moisture is a safety matter as well as a quality one. The IMSBC Code requires the shipper to declare the moisture of cargoes that may liquefy and to show it is below the safe limit. The vessel's master can refuse cargo that looks too wet. Confirm with your charterer or forwarder whether your cargo falls in that group.
Moisture also changes after loading. Rain, condensation and drainage in the hold can raise or lower it on the voyage. That is why the contract should say where moisture is measured for payment and claims.
Quantity and condition
- A draft survey measures the ship's displacement before and after loading to work out cargo weight.
- Weighbridge tickets confirm the weight of each container or truck.
- Hold or container inspection before loading confirms they are clean, dry and free of previous cargo.
- Photographs and a tally of bags give evidence of packing condition.
Next step
We arrange and supervise sampling, testing and loading surveys, and check the results against your contract before the cargo sails. Read the loading survey for bulk chemicals for more on surveys. To plan checks for your cargo, book a free sourcing review.