Rust and Corrosion Damage in Cargo Insurance

Rust and Corrosion Damage and Marine Cargo Insurance

Rust and corrosion damage refers to harm caused to metal products, machinery, parts, steel materials, and similar cargo due to exposure to water, humidity, condensation, salt, packaging conditions, or storage environments during transportation, resulting in rusting or corrosion.

In maritime transport, rust or corrosion may be discovered upon arrival caused by temperature and humidity differences inside and outside containers, long voyages, port detention, rain exposure during cargo handling, moisture intrusion into containers, or moisture absorption by packing materials.

However, the mere fact that rust or corrosion is present does not automatically mean it is covered by marine cargo insurance.

It is important to confirm whether the rust or corrosion arose from an external, accidental incident or whether it resulted from inadequate anti-rust or moisture-proof packing, the inherent nature of the cargo, long-term storage, normal deterioration, or pre-existing damage before shipment.

Even in cases of the same rust damage, the insurance perspective differs between situations such as rainwater intrusion through a container hole versus insufficient moisture-proof packing for normal condensation caused by temperature changes.

Marine cargo insurance evaluates not the mere fact of “rusting” but rather the cause of rust formation, the accidental nature of the incident, the packing condition, the cargo condition before shipment, and the applicable insurance clauses separately.

Scope Covered in This Article

Cargo Prone to Rust Damage

For used machinery, long-term stored cargo, and cargo with outdoor storage history in particular, it is an issue whether rust newly developed during transport or rust that existed beforehand has progressed or become apparent.

Even for new cargo, if anti-rust and moisture-proof measures are insufficient considering the cargo material, voyage duration, climate at transshipment points, temperature changes inside the container, and moisture condition of packing materials, rust may occur.

Main Causes of Rust and Corrosion

• Rainwater penetration through holes, cracks, or defective door packings of containers
• Exposure to rain during cargo handling or before and after loading
• Adherence of seawater or moisture containing salt
• Condensation caused by temperature differences inside and outside the container
• Moisture contained in the cargo or wooden packaging
• Insufficient anti-rust oil, anti-rust paper, or moisture-proof materials
• Insufficient quantity or improper placement of desiccants
• Damage, adhesive failure, or insufficient sealing of barrier packaging
• Long-term storage at ports, CY, CFS, or warehouses
• Progression of rust that existed before transportation
• Materials prone to corrosion or inherent properties of the cargo
• Corrosion caused by contact between dissimilar metals or chemical components
• Normal aging deterioration or surface oxidation

The mere presence of rust does not enable determination of which cause resulted in the damage.

It is necessary to cross-check evidence such as moisture intrusion traces, salt reaction, container condition, packaging specifications, pre-shipment photographs, storage history, and the applicable insurance clause.

Distinguishing External Accidents, Inadequate Packing, and Intrinsic Cargo Properties

For rust damage, the cause of occurrence, applicable insurance conditions, packing condition, pre-shipment cargo state, and timing of discovery are comprehensively verified.

What is Container Rain?

Container Rain refers to the phenomenon where condensation occurs inside a container due to temperature differences between the inside and outside, causing water droplets to form on the cargo or packaging materials.

In maritime transport, condensation inside the container can occur because of factors such as temperature fluctuations between day and night, movement between cold regions and hot, humid areas, weather changes during the voyage, or moisture contained in the cargo or wooden packaging.

The phenomenon where water droplets adhering to the container ceiling or walls fall onto the cargo is sometimes called Container Rain.

When moisture from cargo or packaging evaporates and re-condenses upon temperature decrease, this is sometimes described as Container Sweat.

However, rust damage caused by Container Rain or Container Sweat is not always covered by marine cargo insurance.

Differences Between Seawater Wetting, Freshwater Wetting, and Moisture

Even if a salt reaction is confirmed, this alone does not establish the location of the accident or the responsible party.

It should be confirmed at which stage the seawater adhered, whether it penetrated inside the packaging, and whether salt was present in the storage environment before shipment.

Relationship with ICC(A), ICC(B), and ICC(C) Clauses

Although ICC(A) is often described as having broad coverage, not all damages are covered solely because rust or corrosion occurred.

Under ICC(B) or ICC(C), it is important that the insured risks listed in the clauses have actually occurred and that there is a causal connection between the incident and the rust damage.

Relation to Inadequate Packaging

In rust damage cases, a major point of contention is whether the cargo’s rust prevention and moisture-proof packaging met the transportation conditions.

For metal or machinery cargo, the condition of rust preventive oil, rust preventive paper, volatile rust inhibitors, barrier packaging, desiccants, sealed packaging, wooden boxes, and cushioning materials are verified.

In long-distance ocean shipping, temperature fluctuations, humidity, condensation, and voyage duration can have a greater impact compared to domestic transport.

Simplified packaging intended for domestic storage or short-distance transport may fail to meet rust and moisture prevention requirements needed for ocean transport.

For Used Machinery and Used Parts

For used machinery or used parts, it is important to differentiate between rust, scratches, deterioration, usage marks, and functional degradation that existed before transportation.

Even if rust is found upon arrival, it is necessary to verify whether it occurred newly during transit or if pre-existing rust progressed or became apparent.

With used cargo, pre-shipment photos, third-party inspection records, condition checks before packing, the condition description in the sales contract, "as-is" condition clauses, and pre-transport storage history are all important.

Example 1: Rainwater Ingress through a Hole in a Container

Assume new metal parts were packed in wooden crates and transported in an FCL container, and rust was discovered mainly on the upper part of the cargo upon unpacking after arrival.

Inspection inside the container revealed a hole in the ceiling, with water stains leading toward the cargo around that area.

Pre-shipment photos showed no rust on the cargo, and anti-rust paper and desiccants were used inside the crates, with packaging records preserved.

In this case, the main focus is to verify the causal relationship between the rainwater intrusion through the container hole and the rust damage.

The timing of container damage, EIR, in-gate photos, water stain distribution on the cargo, salt contamination analysis, and damage occurrence segment should be compiled to proceed separately with the marine cargo insurance claim and claims against the shipping line or container operator.

If proper packing is confirmed and an external water ingress path can be identified, there is room to consider the rust damage as resulting from an external and accidental cause.

Example 2: When Existing Rust on Used Machinery Cannot Be Distinguished from Damage During Transport

Consider a used machine that has been stored outdoors for a long period and purchased “as is,” then shipped by sea using a simple waterproof sheet and wooden frame.

Upon arrival, rust was observed in multiple areas of the machine; however, there were only limited photos taken before loading, and it was impossible to prove that those areas were free of rust prior to shipment.

The seller’s condition description stated “surface rust present,” but the storage duration before shipment and records of rust prevention treatment updates were unknown.

In this case, it is difficult to treat all observed rust at arrival as damage caused by an accident during transport.

An investigation should verify whether external incidents—such as moisture ingress into the container or rain exposure during cargo handling—can be confirmed, and whether expert differentiation between new rust and pre-existing rust is possible.

With used cargo, if pre-shipment condition documentation is insufficient, it may be impossible to establish the extent of damage newly caused during transport.

Specific Example 3: Condensation Occurs Due to Insufficient Moisture-Protection Packaging

Consider a case where a precision machine is packed in a standard wooden crate and transported by sea from a cold region during winter to a hot and humid area without using barrier packaging, anti-rust paper, or sufficient desiccants.

Upon arrival, extensive surface rust was observed on metal parts inside the wooden crate, and condensation marks were found on the container’s ceiling and walls.

Meanwhile, the container itself showed no holes, cracks, or defective door seals, nor were there any signs of water intrusion from specific points.

If the moisture content of the wood crate was high and the amount of desiccant was insufficient relative to the cargo volume and voyage duration, the issue likely relates to insufficient moisture-protection packaging against the normally anticipated risk of condensation.

In this situation, not only the fact that container rain occurred is important, but also the cargo's nature, transportation route, packaging design, and any packaging defect exclusions stated in the insurance policy should be reviewed.

Even if the rust results from condensation, if no external accident can be confirmed and necessary moisture and rust prevention measures were lacking, insurance exclusions or conditional limitations may become a significant issue.

Common Practical Problem Cases

Standard Five Classifications of Freight Forwarder Involvement

The five classifications in this article are not legally or industry-wide established categories. They serve as an analytical framework used in this series to organize the scope of freight forwarder involvement.

Contracting Carrier and Actual Carrier indicate legal or contractual positions and do not replace the Standard Five Classifications presented in this article.

Individual tasks such as packing, container inspection, salt analysis, repairs, surveys, or data collection do not constitute a sixth classification by themselves.

Checklist for Freight Forwarder Practical Judgement

Documents Important as Evidence

Decision Flow for Rust and Corrosion Damage

1. Confirm the date, location, discoverer, and unpacking status at the time rust or corrosion was found.
2. Record photos and videos of the entire cargo, extent of rust, areas of spread, and packaging condition.
3. Preserve packing materials, anti-rust paper, barrier materials, desiccants, moisture absorbers, and wooden boxes without disposing of them.
4. Check the container number, seal number, ceiling, walls, floor, doors, and door gaskets.
5. Inspect the container for holes, cracks, signs of leakage, condensation marks, and contamination.
6. Determine whether to check for salt reaction, types of moisture, moisture content of packing materials, and temperature/humidity records.
7. Secure pre-shipment photos, inspection records, pre-packaging condition, and pre-transport storage history.
8. Verify whether the cargo is new or used, and if there was any pre-existing rust or “as-is” condition.
9. Confirm if anti-rust oil, anti-rust paper, barrier packaging, desiccants, and sealing treatments complied with transportation requirements.
10. Classify the cause of rust as external accident, container rain, packaging defects, cargo’s intrinsic properties, pre-existing damage, or long-term storage.
11. Check the insurance policy, ICC clauses, special clauses, rust exclusion, packaging defect exclusion, and insurance period.
12. Notify the insurer or insurance agent of the incident and confirm the need for physical survey by a surveyor.
13. Obtain photos, estimates, and approvals before any rust removal, repairs, reprocessing, parts replacement, or cargo disposal.
14. Notify and reserve liability with carriers, warehouse operators, terminals, packers, and other involved parties.
15. Organize cause of accident, insurance terms, damage amount, third-party liability, and evidence, then submit to insurer, specialized agent, or maritime lawyer.

Common Misunderstandings

Safe Guidance for Freight Forwarder Operations

• Confirm whether marine cargo insurance is in place and which insurance clauses apply.
• Keep photos taken at unpacking, the extent of rust, and the condition of packaging materials.
• Check for water ingress, condensation, holes, dirt, and door gaskets inside the container.
• Secure the container number, seal number, and Equipment Interchange Receipt (EIR).
• Do not discard packaging materials, desiccants, rust prevention paper, or barrier materials.
• Verify photos and inspection records that show cargo condition before shipment.
• For used cargo, confirm existing rust and condition descriptions at the time of sale.
• Contact the insurance company or surveyor before conducting any repairs or rust removal.
• Check the notification deadlines for claims with carriers, warehouse operators, or packers.

As a freight forwarder, it is fundamental to guide clients by stating that “confirmation of the cause of rust, pre-shipment condition, packaging specifications, and official insurance clauses is required” rather than definitively saying “this will be paid by marine cargo insurance.”

Situations When Maritime Lawyers and Experts Should Be Utilized

• When the damage amount is significant and there is a serious impact on machinery functionality or product value
• When it is disputed whether the rust existed prior to transport or newly occurred during transport
• When liability for container holes, water leakage, or defective door gaskets is contested
• When there is disagreement over whether Container Rain or inadequate packaging is the primary cause
• When it is necessary to analyze moisture from seawater, freshwater, condensation, or packaging materials
• When there is dispute over the results of salt reaction analysis and the evaluation of the accident segment
• When a high-value compensation claim has been made by the shipper against the freight forwarder or NVOCC
• When liabilities of the packer, warehouse operator, carrier, and freight forwarder overlap
• When the insurance company asserts exemption based on faulty packaging, inherent defects, or pre-existing damage
• When notification deadlines for accident reporting, claims, or litigation are approaching

Practical Points

• Confirm not only the fact that rust has occurred but also the cause of the rust.
• Distinguish between external accidents, container rain, inadequate packing, the cargo’s inherent nature, existing damage, and long-term storage.
• Verify the moisture intrusion routes, rust distribution, and container condition.
• Delineate seawater, freshwater, condensation, moisture in packing materials, and humidity in the storage environment.
• Check under which condition the insurance is covered: ICC(A), ICC(B), or ICC(C).
• Even under ICC(A), inadequate packing, normal wear and tear, inherent defects, and pre-existing rust could pose issues.
• Confirm the presence of rust preventive oil, rust proof paper, barrier packing, desiccants, and sealed conditions.
• For used machinery, pre-shipment photos, inspection records, and the condition at sale are important.
• Because rust develops over time, preserve evidence promptly at the time of discovery.
• Ensure records are secured before returning the container, disposing of packing materials, or removing rust.
• Separate marine cargo insurance claims from subrogation claims against carriers, warehouse operators, or packing contractors.
• Freight forwarders should not determine coverage or liability but prioritize cause investigation and evidence preservation.

Summary

Rust and corrosion damage frequently occur in cargo such as metal products, machinery, parts, steel materials, and used machinery.

In marine cargo insurance, it is important not only that rust is found but also whether the cause of the rust falls under an insured peril according to the insurance terms.

Rust caused by external and accidental incidents—such as rainwater entering through container holes, exposure to rain during cargo handling, seawater contact, or leakage of contaminated water from other cargo—is potentially covered under marine cargo insurance.

On the other hand, causes such as insufficient anti-rust or moisture barrier packaging, damp wooden packaging, inadequate desiccants, the nature of the cargo itself, normal aging, long-term storage, or pre-existing rust before shipment may lead to exclusions or restrictions under the insurance conditions.

Rust caused by Container Rain or Container Sweat should not be assessed merely by the occurrence of condensation but should be separated into external accidents, ordinarily expected condensation, and insufficient moisture protection packaging.

Seawater, freshwater, condensation, moisture content in packing materials, and storage environment humidity may differ in terms of cause, accident leg, carrier liability, and insurance perspective.

For used machinery or used parts, it is important to check pre-shipment photographs, inspection records, condition descriptions in sales contracts, as-is clauses, and storage history to distinguish newly occurred damage from pre-existing damage.

After discovering the damage, promptly preserve cargo photographs, packaging materials, desiccants, anti-rust agents, container condition records, temperature and humidity logs, pre-shipment documents, and insurance terms.

Before conducting rust removal, repairs, reprocessing, parts replacement, or disposal of cargo, notify the insurance company or surveyor and retain necessary evidence and quotations.

Freight forwarders or NVOCCs need to treat rust damage not simply as a water damage incident but systematically separate external accidents, packaging deficiencies, inherent cargo properties, pre-existing damage, insurance period, and contractual liabilities.

Final insurance claims payments and liability for compensation are individually determined based on the insurance policy, ICC clause terms, special clauses, cause of the accident, packaging condition, pre-shipment status, type of moisture, damage amount, accident leg, and the contractual position of involved parties.

If rust or corrosion is found on metal cargo, machinery, steel materials, or used machinery, prepare cargo photographs, packaging specifications, container photographs, pre-shipment conditions, temperature and humidity records, whether salt content testing is needed, and the insurance policy, then promptly consult the insurance company or an insurance agent specializing in marine cargo insurance for foreign trade.

This article provides general information only and does not determine whether specific rust or corrosion damage is covered by marine cargo insurance, whether it falls under insured perils of ICC(A), ICC(B), or ICC(C), whether insurance indemnity will be paid, or whether the carrier, warehouse operator, packer, freight forwarder, or NVOCC has legal liability.