Stranded Sulphur Cargoes In Strait Of Hormuz Face Significant Structural Corrosion Risk, Warns Brookes Bell
Our take
The recent warning from Brookes Bell regarding significant structural corrosion risks for stranded sulphur cargoes in the Strait of Hormuz underscores a concerning, and increasingly complex, interplay of maritime logistics, geopolitical instability, and material science. The limited lifespan of protective treatments on cargo holds, as highlighted by Brookes Bell, presents a tangible threat to vessel integrity, particularly given the current heightened tensions in the region. This isn't merely an isolated incident; it adds another layer of risk to already precarious shipping routes. The recent events involving Iran’s IRGC Fires Missiles At Two Commercial Ships Near Strait Of Hormuz demonstrate the vulnerability of commercial vessels to regional conflicts, and the corrosion risk presents a silent, insidious parallel threat. Furthermore, the efforts of Japan’s Mitsui OSK Tankers Escape Hormuz In Convoy Via Route Near Iran highlight the escalating need for strategic rerouting and risk mitigation strategies within the maritime sector.
The issue isn’t solely about the sulphur cargo itself; it’s a symptom of broader systemic pressures within the maritime industry. The cost-optimization strategies that often drive decisions around cargo handling and vessel maintenance can inadvertently create vulnerabilities like this. The protective coatings applied to cargo holds are a crucial, albeit temporary, defense against the corrosive effects of sulphur, but their finite lifespan means that any delays or disruptions in transit – precisely what's occurring in the Strait of Hormuz due to geopolitical instability – can expose the underlying steel structure to accelerated degradation. The correlation between these events and the ongoing push for IMO Appoints Full Team Of Regional Coordinators To Expand Global Maritime Support suggests that international bodies are attempting to address the escalating operational challenges faced by maritime transport. However, proactive preventative measures, beyond reactive responses to geopolitical crises, are paramount.
The implications extend beyond immediate vessel repairs and potential insurance claims. Structural failure at sea poses a serious threat to human life, environmental safety, and global trade. A corroded hull can lead to breaches, leaks, and ultimately, catastrophic sinking – with devastating consequences. The economic impact of such an event would ripple through the supply chain, affecting industries reliant on the uninterrupted flow of goods. This highlights the critical need for enhanced monitoring and inspection protocols, particularly for vessels transporting corrosive cargo through high-risk zones. Utilizing real-time data and integrated data ecosystems to track cargo transit times, environmental conditions, and vessel integrity provides an opportunity for predictive maintenance and proactive intervention. Calibrated sensor networks and longitudinal data analysis could identify vessels at heightened risk of corrosion, allowing for timely adjustments to routes or maintenance schedules.
Looking ahead, the situation demands a more holistic approach to maritime risk management. While geopolitical factors remain largely outside of the shipping industry’s direct control, the industry can and must improve its resilience to mitigate the secondary effects. This requires investment in more durable cargo hold coatings, rigorous adherence to maintenance schedules, and the implementation of sophisticated monitoring technologies. The challenge lies in balancing cost-effectiveness with safety and sustainability, and in fostering a culture of proactive risk mitigation across the entire maritime ecosystem. A crucial question to watch is whether the increased scrutiny surrounding vessel safety in the Strait of Hormuz will spur broader adoption of advanced corrosion monitoring techniques and preventative maintenance strategies across the global shipping fleet.
Bulk carriers carrying elemental sulphur cargoes in the Strait of Hormuz are at significant risk of accelerated structural corrosion, with some vessels having remained at anchorage for more than three times the standard cargo protection period, marine consultancy Brookes Bell has warned.
Arron Jackaman, Director of Non-Destructive Testing at Brookes Bell, has urged shipowners, P&I clubs, and hull and machinery insurers to assess the condition of affected dry bulk carriers as soon as possible in order to avoid potential damage and financial loss.
The risk stems from the limited working life of the protective treatment applied to cargo holds before loading, and how far that protection might have already been exceeded on vessels delayed in the Strait.
Elemental sulphur is loaded into bulk carrier holds prepared with a limewash hold block coating, designed to act as a barrier between the cargo and the vessel’s steel structure. Once loaded, the cargo is dampened with a water mist to provide protection for approximately 20 days, after which the steel is exposed.
Once moisture and sulphur come into contact with unprotected steel, an acidic environment can develop, promoting the formation of iron sulphide corrosion products and driving rapid, localised pitting corrosion at rates far exceeding normal seawater exposure.
With some vessels in the Strait of Hormuz having remained at anchorage for upwards of 60 days, Jackaman noted that this protection period has been significantly exceeded and has warned about the risk of further damage to bulk carriers stuck in the region.
“The hold block for carrying sulphur cargoes has a standard working life of around 20 days. Where vessels have been at anchorage for two months or more, that protection has long since been exhausted. The corrosion that can develop once exposed steel is subjected to prolonged contact with sulphur and moisture is orders of magnitude more aggressive than normal seawater exposure,” said Jackaman.
Brookes Bell noted that it has been investigating sulphur cargo claims for vessels that had managed to exit the Strait of Hormuz since February. It noted that it has documented pitting depths in unprotected steel of up to 5 mm forming in approximately 50 days, with some cases even recording wastage of up to 7 mm. The standard corrosion rate in a seawater environment is 0.2 mm per year.
“Sulphur corrosion often appears visually more severe than it actually is. Localised pitting tends to concentrate at points where grab discharge equipment has broken the coating barrier, and on cargo hold tank top plating, which is left uncoated by design. Without correct measurements and quantitative assessment, there is a significant risk that steel within class limits is condemned unnecessarily,” Jackaman explained.
Under Common Structural Rules, bulk carrier cargo hold structures such as tank top plating, bulkhead stools and sloping hopper plating incorporate a sacrificial corrosion allowance of 5.5mm. Visual assessment alone does not account for this margin, and Jackaman has warned that claims based on visual severity routinely overstate the repair strategy and structural renewal that is required.
“Wholesale steel renewal can cost around 10 times more than targeted localised repair. If the extent of repair is being decided on the basis of what the damage looks like rather than what the measurements show, then owners, charterers, and their insurers can end up paying significantly more than the structural condition requires,” said Jackaman.
Brookes Bell has also highlighted crew safety as a consideration, noting that appropriate atmospheric testing, risk assessment and confined space entry procedures must be in place before personnel enter affected cargo holds and adjacent tank spaces.
“Early engagement is critical. The strongest evidence is usually obtained before cargo residues are fully removed, surfaces are cleaned, or repair decisions have already been made. Brookes Bell’s involvement from the point at which damage is first identified gives clients the best opportunity to measure the true extent of corrosion, challenge unnecessary steel renewal and the strongest basis for ensuring repair costs are fair, proportionate, and defensible,” Jackaman added.
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