German corrosion protection specialist Steelpaint has successfully completed a technical field trial of its new Stelcatec-L repair coating on a Liebherr LHM 500 mobile harbour crane operated by ArcelorMittal Nippon Steel.

The test programme at the Hazira Port in Surat, India – made possible through strategic collaboration and support from Steelpaint’s local partner Kaptel Overseas – was carried out on a crane that operates in severe C5 maritime conditions characterised by high humidity and elevated salinity. Kaptel’s help was instrumental in ensuring the seamless completion of the project.

The crane’s surfaces showed significant deterioration and poor coating adhesion of the intermediate and top coating layers and required the removal of damaged and poorly adhering coating layers with surface preparation to Sa2/St3 standards.

Water quality was controlled to keep total dissolved salts below 60ppm, and an alkaline detergent solution was applied to eliminate extensive oil contamination before high-pressure water jetting.

Areas taken back to bare steel received a two-coat system of Stelcatec-L-PR (primer) and  Stelcatec-L-TC (topcoat) applied to total dry film thickness of 280µm. On areas with well-adhering residual primer, the Stelcatec-L-TC topcoat was applied directly  over the existing layer (after roughening), achieving a combined system of 130 to 140µm.

Dmitry Gromilin, Steelpaint’s Technical Service Manager, said the purpose of the project was not simply to deliver advanced corrosion protection, but to validate how the Stelcatec-L system performs under real operating conditions in a severe marine environment, while minimising the lifetime remedial coatings costs for port cranes.

“One of the most striking performance characteristics is the system’s rapid recoat capability,” said Gromilin. “The second coat of Stelpant-1C-PU-Stelcatec-L-TC was applied just 25 minutes after the first, without any damage to the underlying layer.”

Average DFT after two coats was measured at 208.6µm. Pull-off adhesion testing of the completed coating system yielded results of 8.19 MPa and 8.62 MPa, both deemed satisfactory. This is indicative of a well-bonded, robust system.

The project highlighted the practical application advantages of the new Stelcatec-L system in high-temperature field conditions. This included extensive verification and quality controls, salinity testing, DFT measurements and adhesion testing in accordance with recognised ISO standards.

“The combination of controlled surface preparation, rapid curing and strong adhesion performance demonstrated that the technology is well suited to crane maintenance where downtime and environmental exposure are critical considerations,” he said.

Stelcatec-L is Steelpaint’s new moisture-cure polyurethane coating developed for heavy-duty corrosion protection. The system is designed to allow fast overcoating intervals, application at elevated film thicknesses and operation across a broad environmental window.

Steelpaint Director Frank Müller said: “This was a practical repair project carried out under site conditions rather than a demonstration under controlled circumstances. The purpose was to understand how the Stelcatec-L coating behaves where there are existing coatings, heavy contaminations and environmental pressures that maintenance teams deal with every day.

“The work showed that where an existing system still has integrity, there can be value in targeted repair supported by inspection and testing instead of defaulting immediately to complete removal. Stelcatec-L simplifies application, shortens return-to-service timeframes and supports long-term infrastructure resilience in corrosive environments.”

The trial application was completed on the exterior section of the crane’s right rear outrigger and will remain under observation as part of Steelpaint’s ongoing evaluation of coating performance in heavy industrial and port environments.