How can we extend the service life of fasteners in coastal solar power plants? The answer is actually quite clear: we must adopt a targeted, comprehensive solution that addresses multiple aspects, including material selection, design optimization, installation techniques, post-installation maintenance, and system protection. The coastal environment is extremely harsh on metal fasteners; high salt fog, high humidity, intense UV radiation, and temperature fluctuations collectively act as a “corrosion accelerator.” Therefore, extending their service life cannot be achieved through a single measure but requires a systematic approach involving full lifecycle management.
What should be done? The first step is to select truly corrosion-resistant materials. For coastal solar power plants, ordinary galvanized carbon steel fasteners are far from sufficient. The material grade must be upgraded. The preferred option is high-quality stainless steel, such as 316 or 316L stainless steel, which contains molybdenum and offers significantly better resistance to chloride ion pitting and crevice corrosion than 304 stainless steel. For critical areas with higher load requirements, duplex stainless steel can be considered. Secondly, carbon steel components treated with hot-dip galvanizing followed by a sealing coating (such as chromium-free zinc-aluminum coatings like Dacromet or Jumeite) are also a cost-effective option; the coating provides dual protection for the base metal through sacrificial anode protection and a physical barrier. The use of ordinary black metal fasteners without adequate protection must be strictly avoided.
What should be done? Corrosion prevention must be integrated into the fastener design and selection phase. This includes prioritizing designs that minimize water accumulation and salt retention. For example, use hex socket head cap screws rather than hex head bolts whenever possible to reduce exposed surface area and water-retaining depressions. Washers should be selected from materials compatible with the bolts, and combinations featuring sealing rings or polyurethane washers should be considered to prevent corrosive media from entering the threaded connection. The design must also ensure sufficient preload and account for anti-loosening requirements under long-term vibration and wind loads, as loosening exacerbates fretting wear, damages protective coatings, and accelerates corrosion.
What should be done? Strictly standardized installation procedures are key to ensuring that the design’s protective performance is achieved. During installation, the correct tools must be used to ensure precise torque—neither too tight, which could damage the coating or strip the bolt threads, nor too loose, which could cause connection failure. Extra care must be taken when installing coated fasteners to avoid scratching the coating during the process. For certain specific coatings or materials, secondary sealing or recoating may even be required at the thread heads or notches after installation to repair installation damage. Additionally, installation should ideally be conducted during dry periods with low salt fog levels, and direct hand contact with the cleaned fastener surfaces should be avoided to prevent contamination from sweat.
What should be done? Establishing a proactive, periodic inspection and maintenance system is crucial. One should not assume that installing high-performance fasteners guarantees a permanent solution. A detailed inspection plan should be developed, utilizing methods such as high-definition drone imaging and close-range manual inspections to regularly check for rust, coating blistering or peeling, and signs of loosening. Any early signs of corrosion or loosening must be addressed immediately. Maintenance measures include cleaning surface salt deposits, professionally repairing localized coating damage, and retightening or replacing loose fasteners to the specified torque. This “early detection, early intervention” strategy effectively prevents minor issues from escalating into structural safety hazards.
What should be done? In addition to the fasteners themselves, a better microenvironment can be created for them from a system protection perspective. For example, in the design of PV mounting systems, consideration should be given to overall drainage and water flow to prevent seawater or condensation from accumulating at connection points. For certain particularly critical areas or those with extremely high corrosion risks, additional protective measures can be considered, such as wrapping with anti-corrosion tape, applying heavy-duty anti-corrosion coatings, or employing cathodic protection technology. Although these measures increase initial costs, their long-term benefits are significant in ensuring the safe operation of the power plant for over 25 years.
In summary, there is no magic “one-size-fits-all” solution for extending the service life of fasteners in coastal PV power plants. So, what should be done? The answer is: Lay a solid foundation by selecting materials such as 316 stainless steel or high-quality coatings; optimize the approach by improving water drainage design; fasten everything securely through standardized installation; regularly inspect and maintain the system; and supplement these efforts with necessary system-wide protection. Only by seamlessly integrating these five aspects into a comprehensive management cycle can we effectively withstand the corrosive effects of the harsh marine environment, ensure the long-term stability and reliability of the PV power plant’s fastening system, and thereby lay a solid foundation for the plant’s sustained operation and stable returns.