LIQUID CARGO – HOW TIME AND PLACE OF SAMPLING CAN MAKE A DIFFERENCE

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Published: 19 June 2025

Given that even trace contaminants can result in cargo being declared off-specification, the importance of proper sampling cannot be overstated. Its effectiveness, however, is fundamentally influenced not only by the method but also by the timing and location of sample collection. Each designated sampling point – whether at the shore tank, shoreline, ship’s manifold, or cargo tank – serves a specific evidentiary function and must be understood in context.

Where sampling practices are inconsistent or improperly executed, the risk of misinterpreting cargo quality and misattributing contamination increases. In many cases, even when contamination originates ashore, it is still typically the ship that bears the burden of proof to establish that it is not responsible for the quality discrepancies.

Through various scenarios and real-world examples, we will demonstrate how robust sampling practices contribute to safeguarding the ship’s interests and supporting fair, credible cargo quality assessments. A good understanding of these principles can help reduce risks and ensure clear evidence is available in the event of a cargo quality dispute.

SUITABILITY OF SAMPLING POINT

As illustrated above, while both points are widely considered sampling points, they are designed to serve different purposes: the sampling point at the shoreline is generally used to verify line fullness during packing, whereas the one at the ship’s manifold is intended to capture sediments and water, which typically settle at the bottom of piping.

REAL-WORLD PERSPECTIVES

that might have originated from shorelines or shore tanks (including rust, suspended matter, or residues from previous cargoes) may be wrongly attributed to the ship if not successfully captured during sampling. Though not exhaustive, the following may help visualise and better understand the significance of various points, stages and timings of sampling.

SAME TIME, DIFFERENT POINTS

These two samples were taken at the same time after a settling period – following the stop of the shore loading pump and with residual pressure still in the line system – and showed significant differences upon visual inspection.

Consider a scenario where a ship and a shore terminal dispute the cargo. If the shore terminal relies solely on its visual inspection of the cargo at the shoreline (which may not be representative of the cargo) and dismisses any discrepancies observed by the crew, this can put the ship at a disadvantage. The ship may struggle to prove its case without obtaining samples directly from the manifold.

By taking and retaining their own samples at the manifold, ships can ensure they have a reliable reference to counter any claims made by the shore terminal and could provide crucial evidence in verifying the apparent preloading condition of the cargo.

SAME POINT, DIFFERENT TIME

Here, we have two samples taken: one at the initial loading or “first flow” and another after ten minutes of flushing at the manifold. If the ship’s manifold was inspected to be clean and acceptable before the hose or loading arm is connected, then it is evident that there are residues (previous cargo/contaminants) coming from the shoreline. In this particular case, the surveyors’ initial sampling at the shoreline confirmed this issue and recommended keeping the manifold valve shut while flushing continued.

At first glance, one might assume that a small quantity or slight discoloration from previous cargo would not significantly impact the overall quality of the intended cargo for loading. While this may be true for some types of cargo, there are highly sensitive cargo grades where critical parameters are measured in the parts per million (ppm) range. In such cases, a small but highly incompatible previous cargo can cause the entire cargo to be declared off-specification (off-spec) after loading.

The crew should always promptly take and retain the initial loading manifold sample. This sample could provide a useful trace to the possible origin of a particular contaminant found in the cargo and establish that the ship was not at fault.

AFTER DYEING

Dyeing for various types or grades is not uncommon, whether for regulatory, tax, or operational reasons and typically should not affect the chemical properties of the cargo. The charterers or receivers set the agreed specifications. However, even with a Letter of Indemnity (LOI) in place, issues may still arise if the cargo’s colour after dyeing appears too light or too dark. Such discrepancies could indicate inherent problems with the dye itself or improper dosage by the doping team.

To address this, it may be recommended to sample a small clear bottle from each tank after the settling time. A quick visual inspection of these samples can help identify any abnormalities, which should be reported to the owners and charterers. In many cases, such issues are of particular concern to the charterers, who need to ensure that the dyeing process meets the agreed commercial specifications and any applicable customs or import regulations.

AFTER DOPING

In this case, the difference between the before- and after- doping samples is not noticeable. Doping is generally done to maintain or correct the cargo’s properties to meet agreed-upon commercial specifications and quality. However, this process can present a liability to the ship if something goes wrong, resulting in the cargo being delivered off-spec. Receivers unaware that the cargo needed doping may incorrectly attribute any off-spec results to improper carriage or handling on the ship’s part.

Retaining a sample before doping (immediately after loading) and after doping can be crucial. It should not be assumed that post-loading samples are alone sufficient, and no further sampling is required after doping. Similarly, the ship should not wait until after doping to start sampling, as this would mean missing the opportunity to capture a sample representing the cargo’s quality immediately after loading.

By retaining samples at both stages, the ship could better demonstrate the quality of the cargo throughout the entire process and mitigate potential disputes.

SAMPLING EQUIPMENT

Another critical aspect to consider is the sampling equipment used. A notable case illustrates this: a chemical tanker transporting a chemical product faced a significant contamination claim due to improper sampling. The ship utilised a modified and unapproved sampling hose extension, intended to make sampling more convenient. Unfortunately, this modification resulted in the contamination of the samples due to the reaction of the cargo with the hose material. The samples collected then indicated high levels of organic chlorides. In contrast, samples taken using the ship’s dedicated hermetically sealed system showed no contamination. This modification to the sampling equipment went unnoticed by the shipping company’s operational audits, vetting inspections, and external cargo surveyors due to its discrete and minor nature.

This incident highlights the importance of using appropriate sampling equipment and methods to ensure reliable results. Regular checks and proper procedures are the key to avoiding costly mistakes. Crew members should be trained in the correct use of the sampling equipment and made aware of the potential risks associated with using unsuitable or makeshift alternatives. This approach will help to minimise contamination risks and supports accurate, consistent sampling.

WHAT TO LOOK OUT FOR?

When collecting samples, it is essential to use a clean and clear receptacle (typically 500ml bottles) to perform a visual inspection to identify any potential contamination/quality issues. Key aspects to check include:

• Cloudiness/haziness
• Suspended matter
• Rust
• Colour
• Water/free water

If any signs are detected, loading or discharging operations should be suspended without delay. The owners or charterers should also be promptly notified to obtain further advice and instructions proceeding.

LOCATION OF SAMPLING

LOAD PORT SHORE TANKS SAMPLES

Typically, these samples may not be taken or even witnessed by the ship’s crew. Always try to request for these samples from shore tanks before loading if permitted by the load port terminal personnel or request them through an officially appointed surveyor. These samples may be used to establish the initial condition of the cargo as they set a baseline for cargo quality and can help identify pre-existing issues.

SHORELINE SAMPLES

Depending on terminal regulations, shoreline sampling may or may not be permitted. If allowed, take samples from the shore manifold after any line flushing operations to detect any potential contaminants, if present. This is particularly important if the terminal has conducted preparatory line packing or displacement operations prior to loading. Shoreline samples can reveal contaminants introduced during shore operations, which are not the ship’s responsibility.

MANIFOLD SAMPLES

This may arguably be the most important sample, as it determines whether the cargo remains within specifications as it passes through the manifold. Where the manifold configuration allows, valves should remain shut until the cargo at the manifolds is found to be satisfactory.

• Start of Loading: Draw a sample at the ship’s manifold at the commencement of loading to compare with subsequent samples from the cargo tanks. This “first flow” or “flushing” sample is critical for assessing the initial quality of the cargo. At this stage, it is advisable to minimise the loading rate so that if visible contaminants are detected or visual checks raise concerns requiring suspension, the volume of potentially contaminated cargo (if loaded) is kept to a minimum. This precaution is particularly relevant in cases where cargo has already entered the ship’s tanks due to manifold valve or sampling point configurations that make sampling for visual checks not possible without first opening the manifold valve.
• Regular/Appropriate Intervals: Collect manifold samples at regular intervals throughout the loading operation, particularly after any stoppages or changes in shore tanks. Always take samples representing the first flow of every grade of cargo being delivered. These regular sampling checks support continuous monitoring of cargo quality and create the opportunity to allow for the early detection of any changes in the cargo condition.
• Start of Discharge: Similarly, at the start of the discharge operation, take samples from the manifold to provide evidence that the cargo’s integrity is still intact at the final point on the ship before it passes through the shore hose or loading arm.

OTHER PHASES/STAGES OF SAMPLING

FIRST FOOT SAMPLES

Take a “first foot” sample from each cargo tank shortly after loading commences. This sample helps to verify the cleanliness of the tanks and lines. First foot sampling is especially important for sensitive or high-value cargoes, and where analysis may be required for the first tank – or for every tank – depending on what has been commercially agreed or as part of the charterer’s or end receiver’s quality assurance strategy to limit exposure and mitigate risk. Although case-specific, such samples may still suggest that contamination originated ashore or to underlying issues introduced prior to the cargo reaching the ship. Conversely, they may also point to contamination from residual substances within the ship’s tanks or lines.

SHIP’S TANKS, AFTER LOADING SAMPLES

Samples taken after loading are typically included in the master’s receipt of samples. Ensure that the sealed samples listed in the master receipt were properly witnessed and taken directly from the ship’s tanks. The ship should be careful not to sign for anything that is unrepresentative, inaccurate, or suspected to be from other dubious sources.

SHIP’S TANKS, BEFORE DISCHARGE SAMPLES

These samples, taken before starting discharge, may serve as compelling evidence that the cargo’s integrity remained intact upon delivery, thereby protecting the ship against claims of alleged mishandling or contamination during the voyage.

SAMPLING EQUIPMENT AND SAMPLES HANDLING

Clean equipment: Ensure all sampling equipment, including sample bottles, is clean and free from contaminants. Contaminated equipment can introduce impurities into samples, leading to inaccurate results. It is also important to use equipment manufactured with suitable materials to prevent reactions with the cargo.

Proper containers: Use suitable sample containers, typically clear glass bottles for visual inspection, and appropriate containers for retention based on the cargo type. For example, light-sensitive samples should be stored in dark amber bottles, some petroleum products may require epoxy-coated containers, and chemicals might need glass or plastic containers based on their reactivity.

Sealing and labelling: Seal all samples and label them accurately with details such as the ship’s name, date and time, cargo type, location, sampling personnel, and sample type/stage. Labels should ideally be completed using permanent ink appropriate for the label surface and resistant to fading or smudging, as unclear or faded markings can make identifying samples later extremely difficult. Proper sealing ensures that the sample remains untampered, while accurate labelling aids in identifying and tracking samples. This is not just good practice; it allows the sample to stand up to scrutiny if a claim arises.

STORAGE AND RETENTION

Dedicated storage: Avoid storing samples in areas prone to temperature fluctuations or direct sunlight. Samples should be stowed and secured to prevent damage from the ship’s movement and stored in a dark, well-ventilated locker away from accommodation and food storage areas. Keeping a copy of the Safety Data Sheet (SDS) with the samples is considered good practice for easy reference of associated hazards and handling precautions, especially when dealing with hazardous chemicals or unfamiliar substances.

Retention period: Retain samples as per company policy (or charterers’ instructions) referencing industry standards. In cases of dispute, retain the samples until the issue is resolved. This ensures that samples are available for necessary analysis during dispute resolution processes. In cases of long-term storage, periodically check the samples’ condition and storage environment.

Chain of Custody: Never release ship samples to any third party without explicit approval from the ship’s designated reporting line ashore. If there is any uncertainty about the situation, seek guidance from the same reporting line before proceeding. Ensure that any transfer of samples is accompanied by a receipt and signed/stamped acknowledgment from the receiving party.

BEST PRACTICES FOR CREW

Training and PPE: Ensure crew members are trained in the proper inspection and use of onboard sampling equipment and the appropriate personal protective equipment (PPE), such as gloves and eye protection, when handling samples. Training should cover handling different types of cargo and the specific hazards associated with each. Understanding the various risks involved can help prevent exposure to hazardous substances and reduce the likelihood of improper handling.

Documentation: Maintain a detailed sample logbook, recording all samples taken, their locations, visual examination results, and any other relevant observations. This logbook may assist future investigations and provide a clear record of sampling activities. It should be regularly reviewed and kept up to date.

Independent sampling: A common issue observed is that ships often witness sampling conducted by surveyors at critical stages during loading and discharge but fail to retain their own (sealed) set of corresponding samples—independent of those retained by charterers or surveyors. This disadvantages the ship in a quality dispute, as it may be forced to rely solely on third-party samples.

CONCLUSION

To protect the ship’s position in a cargo quality dispute, the crew must go beyond merely witnessing third-party sampling and actively manage the ship’s own sampling responsibilities. Sole reliance on samples retained by other parties – whose commercial interests may differ – can leave the ship exposed. Considering the risks involved, a robust sampling strategy should include a clear understanding of the purpose of each sampling point, the retention of samples at critical stages, the use of approved equipment, and the maintenance of accurate records and supporting documentation.

For this reason, a well-structured and disciplined approach to sampling not only helps to demonstrate that the ship bears no responsibility in the matter but also strengthens its ability to respond credibly and effectively to any claims that may arise.

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