--- type: "Article" title: "Galvanic coupling: securing a naval assembly" description: "Case study Galvanic coupling: securing a naval assembly One of our customers encountered sealing issues during the final validation tests of their product. Accueil • Blog • Galvanic coupling: securing a naval assembly The problem? A shipyard is designing a..." resource: "https://filab.fr/en/blog/2025/12/galvanic-coupling-securing-a-naval-assembly/" tags: ["Case study", "EN", "pll_691f1111d7c02"] timestamp: "2026-03-10T13:07:33Z" published: "2025-12-02T07:05:35Z" language: "en" author: "bwa" --- # Galvanic coupling: securing a naval assembly Case study # Galvanic coupling: securing a naval assembly One of our customers encountered sealing issues during the final validation tests of their product. [Home](https://filab.fr) • [News](https://filab.fr/?post_type=post) • Galvanic coupling: securing a naval assembly ## The problem? **A shipyard is designing a new service vessel with a steel hull and aluminum superstructure to lighten the structure.****These two metals are joined using a specific welding technique. The design office is concerned about the risk of accelerated galvanic corrosion at the joint, which will be constantly exposed to seawater.** **A failure at this critical point could compromise the structural integrity of the ship. The customer asked FILAB to solve this problem by conducting a galvanic coupling study.** To assess this risk, we conducted a galvanic coupling study in accordance with ASTM G71. ## Summary 01 Galvanic corrosion risk assessment [](#cont-01) 02 Our technical approach [](#cont-02) 03 The benefits of this analysis for the client [](#cont-03) 04 Conclusion of the study [](#cont-04) 01 ## Galvanic corrosion risk assessment **Objective:** The main objective of this study is to provide the shipyard with a quantitative and predictive assessment of the risk of [**galvanic corrosion**](https://filab.fr/en/our-services/our-expertise-services/electrochemical-characterization/study-galvanic-corrosion.md) associated with the steel hull/aluminum superstructure assembly, in order to ensure the structural integrity of the new service vessel,& nbsp;while avoiding high post-construction maintenance and downtime costs. 02 ## Our technical approach To assess this risk, we conducted a galvanic coupling study in accordance with ASTM G71. ##### Step 1: Setting up the electrochemical cell The first step was to prepare the sample. **Plates of [steel](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/laboratory-of-analysis-and-expertise-of-steels.md)** (representing the hull) and [**aluminum**](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/laboratory-analysis-aluminum-alloys.md) (representing the superstructure) were assembled and **electrically connected** within an electrochemical cell. The cell was then filled with artificial seawater to accurately replicate the operating environment and initiate the corrosion reaction. ##### Step 2: Initial measurement and monitoring Next, we proceeded to the measurement phase. The **coupling current** and **coupling potential** were measured continuously. The coupling current is the key indicator of the [**corrosion rate**](https://filab.fr/en/our-services/our-expertise-services/electrochemical-characterization/study-corrosion-speed.md) of the least noble metal (aluminum, in this case), providing a direct reading of the deterioration of the material. #####   ##### Step 3: Observation of the system's evolution Finally, the test was maintained **over several days**. This extended duration made it possible to observe the **evolution of the system** over time, and more specifically to detect and analyze the possible formation of **protective layers** ([a phenomenon known as **passivation**](https://filab.fr/en/our-services/our-analysis-services/laboratory-surface-characterization/laboratory-characterization-passivation.md)) that could modify the kinetics of corrosion. ![](https://filab.fr/wp-content/uploads/2025/10/ecovadis-90-e1761922275877.png) 03 ## The benefits of this analysis for the client   The test confirmed that aluminum would behave as a sacrificial anode, corroding preferentially to protect the steel, with an initially very high corrosion rate at the junction. This data enabled the shipyard to: **• Anticipate a major corrosion phenomenon** even before construction began. **• Make informed design decisions** by incorporating a cathodic protection system (sacrificial zinc anodes) precisely sized to protect the [weld](https://filab.fr/en/our-services/our-expertise-services/laboratory-analysis-failures/laboratory-analysis-welds.md) area. **• Ensure the safety and durability** of the ship, avoiding extremely high maintenance costs and the risk of downtime. 04 ## Conclusion of the stud The study of **galvanic coupling** conducted in accordance with ASTM G71 standard has transformed a theoretical uncertainty into critical quantitative data for naval design. Continuous measurements of **coupling current** and **coupling potential** confirmed the existence of a strong **electrochemical** interaction between the steel hull (cathodic) and the aluminum superstructure (anodic) in seawater. Ultimately, this preventive approach, validated by applied **electrochemistry**, guarantees the **safety** and **durability** of the ship. It has enabled the shipyard not only to technically validate its design, but also to provide assurance of structural reliability to the ship operator, avoiding considerable financial and operational risks. Need help? Contact our team [](#filab-contact-form) ## Other case studies you may be interested in ### [Learn more +](https://filab.fr/en/blog/2026/05/microplastics-detection-industrial-filters.md) ### [Learn more +](https://filab.fr/en/blog/2026/01/marking-problem-biopolymer-packaging.md) ### Piston failure A piston is a crucial mechanical component in many mechanical devices and engineering systems. Pistons enable various applications, including: [Learn more +](https://filab.fr/en/blog/2025/12/how-did-filab-help-one-of-its-clients-determine-the-cause-of-steel-piston-failure-at-the-rod-case-study.md) [View all our case studies](https://filab.fr/en/blog-filab.md) ## Services related to the case study [## Galvanic Corrosion Study in the Laboratory](https://filab.fr/en/our-services/our-expertise-services/electrochemical-characterization/study-galvanic-corrosion.md) [## Galvanic Coupling Test – Electrochemical Test](https://filab.fr/en/our-services/our-expertise-services/electrochemical-characterization/galvanic-coupling-testing.md) [## Impedance measurement in laboratory – electrochemical test](https://filab.fr/en/our-services/our-expertise-services/electrochemical-characterization/impedance-measurement.md) [## Electrochemical testing](https://filab.fr/en/our-services/our-expertise-services/electrochemical-characterization.md) [![avis filab](https://filab.fr/wp-content/themes/astra-child/templates/assets/img/avis-verifies.svg) 5/5 ![note filab](https://filab.fr/wp-content/themes/astra-child/templates/assets/img/stars.svg)](https://www.avis-verifies.com/avis-clients/filab.fr) ## Laboratory specializing in analysis and expertise for industrial companies ![More than 140 people](https://filab.fr/wp-content/uploads/2024/10/collaborateurs-1.svg) More than 140 people at your service ![5200 m² laboratory](https://filab.fr/wp-content/uploads/2024/10/labo.svg) 5200 m² laboratory + 99% of services are provided in-house ![Accredited laboratory](https://filab.fr/wp-content/uploads/2024/10/ISO-17025-1.svg) Accredited laboratory COFRAC ISO 17025 ![+2200 clients](https://filab.fr/wp-content/uploads/2024/10/clients.svg) +2200 clients in France and abroad ### Contact us Our services are reserved for professionals. 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