Rust prevention treatment of welding seams in rural lighting ready boards in Africa

The outdoor environment in rural Africa has large temperature differences and strong ultraviolet radiation, and some areas are accompanied by salt spray and humid condensation. The welding parts of the lighting Ready Board Box must undergo special rust prevention treatment. High temperature welding can damage the original galvanized layer of the substrate, and there are welding slag, micro gaps, and stress concentration in the weld and heat affected zone, which are the most prone to corrosion and failure of the box. Relying solely on overall spraying is not enough to ensure long-term corrosion prevention, and local coating bubbles, cracks, and red rust problems are prone to occur in the weld.

After welding, surface pretreatment should be carried out first, grinding and removing welding slag, spatter, and high-temperature oxide layer, smoothing the weld seam, and eliminating dead corners caused by water accumulation and dust accumulation; Subsequently, oil and dust removal will be carried out, with priority given to sandblasting treatment to achieve Sa2.5 level, fully enhancing the adhesion of the coating and avoiding residual impurities that may cause the coating to peel off.

There are two mainstream anti rust processes: hot-dip galvanized sheet metal box body and lighting ready board. After the welding of the zinc layer is damaged, the weld area is coated with zinc rich primer/cold spray zinc for cathodic protection. The zinc content is ≥ 90%, forming a sacrificial anti-corrosion layer, and then entering the overall phosphating and electrostatic spraying process. Outdoor weather resistant polyester powder is used for spraying, and the weld position ensures that the paint film thickness is not less than 80 μ m to prevent film leakage. Cold rolled steel plate box body, the welds are polished and sandblasted, converted into a zinc based phosphating film, and then sprayed as a whole. The welds can be reinforced with an additional layer of epoxy primer.

During the production of lighting ready boards, it is strictly prohibited to spray paint directly without polishing after welding, and there should be no residual flux impurities in the weld seam gaps. The finished product must meet the requirement of 240 hours of neutral salt spray without red rust, suitable for long-term outdoor use in African rural areas, reduce on-site maintenance frequency, and ensure the service life of the box.