Risks of transporting in bulk containers (FIBCs)

FIBCs (Flexible Intermediate Bulk Containers) are a crucial tool for bulk cargo transportation due to their large capacity (typically 500kg to 3000kg) and lightweight construction (primarily woven polypropylene with a polyethylene inner layer). However, they face numerous risks and compliance requirements during maritime transport that cannot be ignored. This article systematically examines the core risks, relevant regulatory requirements, and safety management recommendations for FIBC transportation, providing a reference for industry practice.

The risks associated with bulk bag transport at sea extend throughout the entire process of cargo loading, navigation, and unloading, primarily manifesting in the following areas:

1. Cargo Deformation and Shift

Ship movements during severe weather can lead to significant deformation and shifting of cargo within bulk bags. This risk is primarily due to two factors: uneven filling and an imbalance in the distribution of material properties. The tensile strength of the bulk bag becomes crucial in preventing cargo shifting. If the bag ruptures, its inherent stabilizing effect is negated, potentially exacerbating the instability of the entire cargo stack.

The risk is even more pronounced for Group A cargoes (easily liquefiable cargoes). Even if tightly stacked, if the cargo load exceeds its flow moisture point (FMP), the likelihood of deformation and compression under external pressure increases significantly. Furthermore, cargo shifting is a secondary risk. If bulk bags lack support, cargo will attempt to fill the gaps when the ship rolls. Lateral pressure can cause the cargo to shift upward within the bags, increasing lateral slack. Cargo shifting on multiple decks can even cause the ship to list severely.

2. FIBC Integrity

The structural strength of FIBCs is directly related to cargo safety. Damage or tears in FIBCs during loading, unloading, and transportation can easily lead to cargo leakage, contamination, and even loss of product integrity. In practice, excessive top loading is a common cause of damage-shifting during transport can cause damage during unloading, and excessive top loading has even directly caused FIBC rupture.

3. Cargo Characteristics: Chemical and Thermal

Many cargoes transported in FIBCs present inherent chemical risks. Some cargoes release toxic or flammable gases that may not be detected by standard personal gas monitors (which typically detect oxygen, methane, carbon monoxide, and hydrogen sulfide), posing a safety hazard to crew members entering cargo holds. For example, ferrosilicon (UN1408, Group B, Class 4.3, Subsidiary Hazard Class 6.1) can release highly toxic arsine and phosphine gases. According to the International Maritime Solid Bulk Cargoes (IMSBC) Code, vessels transporting these cargoes in bulk must be equipped with hydrogen, phosphine, and arsine detectors and monitor them at least every eight hours.

Furthermore, some Group A cargoes, such as copper concentrate, are self-heating. When these cargoes are packed into bulk bags, heat can easily accumulate, significantly increasing the risk of fire within the bags.

4. Stacking Height Control

When loading Group A cargoes or materials prone to caking, it is crucial to determine the maximum safe stacking height of bulk bags. This height is primarily determined by the maximum stacking load indicated on the bulk bag itself and has no fixed regulatory limit. As long as the bottom bag does not exceed the specified stacking load, the stack is secure and tight, and any gaps are properly filled, the stacking height is sufficient. In practice, bulk bags are often stacked to the hatch coaming level, but the compaction characteristics of the cargo must be considered. For example, automotive-grade urea compacts more easily than agricultural-grade urea, so the stacking height should be reduced to avoid excessive consolidation.

5. Fire and Chemical Incompatibility Risks

While cargo is not a common initial source of fire, incidents have occurred at loading and unloading ports where discarded cigarette butts from stevedores ignited the packaging and filling materials of bulk bags. Such fires can also release toxic gases from the cargo, making firefighting more difficult.

Chemical incompatibility is another significant risk. It is difficult for crews to fully understand the compatibility of various chemicals, so ideally, different chemicals should not be loaded in the same hold. If mixed loading is necessary, the shipper must obtain the Safety Data Sheets (SDS) for all chemicals, and the manifest must be reviewed by an expert to ensure that there are no incompatible goods or misdeclarations. Otherwise, damaged bulk bags could cause the chemicals to mix, potentially leading to fires or reactions in the hold, resulting in cargo losses, increased cleanup costs, and shipping delays.

Transporting bulk bags (FBs) is subject to numerous international regulations, with the key focus being on clearly defining applicable standards and operational requirements:

1. Applicable Regulations: The Difference Between IMSBC and IMDG

Cargo transported in FBs is not considered bulk cargo. Shippers may use bagging to circumvent the requirements of the International Maritime Solid Bulk Cargoes (IMSBC) Code for liquefiable cargoes (Group A) or dangerous chemicals (Group B). In such cases, the cargo must comply with the International Maritime Dangerous Goods (IMDG) Code. Note that if Group A cargoes are classified as UN 3077 (Environmentally Hazardous Substances, Solid, Not Otherwise Specified) after being packed in FBs, shippers must provide a Dangerous Goods Declaration Form.

2. Core Requirements of the International Maritime Organization (IMO)

Regulation 5.1 of Chapter VI, "Cargo Transport," Part A, of the International Convention for the Safety of Life at Sea (SOLAS) stipulates that cargo, cargo units, and transport units, both above and below deck, must be loaded, stowed, and secured in a manner that, throughout the voyage, prevents, to the greatest extent possible, damage or danger to the vessel or personnel, and cargo from falling overboard. Regulation 5.6 requires all ships transporting non-solid and liquid bulk cargoes to carry an approved Cargo Securing Manual (CSM). MSC/Circ.745 issued by IMO provides guidance on the compilation of the manual.

The Safe Practice Code for Cargo Stowage and Securing (CSS Code) provides specific recommendations for transporting bulk bags:

Ideally, the vessel should have wide hatches, allowing bulk bags to be placed directly into the stowage position;

Cargo holds should be rectangular and free of obstructions. For ships with two decks, if bulk bags are to be loaded in deep hold wings, sufficient access and maneuvering space must be ensured for forklifts.

The code also specifies that transverse loading of bulk bags should be initiated from both sides of the hold, concentrating and filling any gaps in the center.

Partial loading requires securing with stanchions, and steel wire lashings (rather than synthetic ropes that are prone to stretching or lack strength) should be used for added stability.