Hot-dip galvanizing is the most common solar racking corrosion protection. Coating thickness directly determines outdoor life. Purchasing and acceptance must specify thickness and measurement.
Per ISO 1461 and GB/T 13912, average coating is typically ≥45μm for steel sections ≥6mm, and fasteners generally ≥40μm local thickness. Coastal and heavy-corrosion projects often require 65-85μm.
Use magnetic gauges on head and shank, averaging readings. Check uniformity, bare spots and zinc runs. Salt spray usually requires ≥480-720 hours without red rust.
Hot-dip galvanizing thickens threads; use calibrated torque wrenches or re-tap. High-strength bolts need pre-plating baking to avoid hydrogen embrittlement.
The solar fastener range supplies HDG bolts with coating test reports.