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Railings & Guardrails

Enhanced protection for welds, edges and outdoor exposure

Railings and guardrails include balcony railings, stair handrails, road barriers, bridge fencing and other metal barriers. Long-term exposure to ultraviolet radiation, rain, temperature changes and frequent contact requires weatherability, corrosion protection, adhesion and scratch resistance.

Veri Coating offers super-durable polyester-HAA smooth powder with at least 90% gloss retention after 1,000 hours of xenon-arc exposure and compliance with Qualicoat Class 2 requirements, as well as standard-durable polyester-TGIC textured powder and high-durable polyester-TGIC smooth powder. Where the required weathering level is met, TGIC systems provide a greater cost advantage.

Application notes: Powder coverage on edges, hanging points and temperature should be controlled, with a recommended film thickness of 60-120 um.

Typical Powder Coating Challenges for Railings & Guardrails

Insufficient Impact and Chip ResistanceImpact cracking and substrate exposure create initiation sites for subsequent corrosion.

Insufficient Impact and Chip Resistance

Impact during transport, installation or use can crack or chip the coating on railings and expose the substrate. Excessive hardness, brittle low-gloss systems, unsuitable film thickness, undercure or substrate deformation can reduce impact performance, and damaged areas then become corrosion initiation sites.

Formulation Design

  1. Balance hardness, flexibility and adhesion in the polyester system instead of pursuing hardness alone.
  2. Optimise impact and bend performance separately for low-gloss, textured or high-film-build products.

Process Control

  1. Control film thickness and degree of cure to prevent embrittlement from excessive build or overbake.
  2. Use soft separators and impact-resistant packaging during transport and installation, with a touch-up procedure after installation.
  3. Complete welding and forming before pretreatment and coating to minimise post-coating fabrication damage.
Validation Focus
  • Impact resistance
  • Bend/cupping
  • Transport simulation
  • Salt-spray creepage from damage
Corrosion Failure at Welds, Cut Edges and Tube EndsLow film build at welds, cut edges and tube ends makes them the earliest corrosion sites.

Corrosion Failure at Welds, Cut Edges and Tube Ends

Welds, tube cut ends, sharp edges and open tube ends on railings often corrode first. Causes include residual slag and mill scale, water trapped in cavities, low film build at sharp edges, poor weld deposition from the Faraday cage effect, and unsealed cuts made after coating.

Formulation Design

  1. Improve edge coverage and corrosion resistance; in highly corrosive environments, use an epoxy powder primer with a polyester topcoat.
  2. Select a system suitable for touch-up and recoating according to tube geometry and the required corrosion category.

Process Control

  1. Remove slag, spatter and mill scale completely after welding, round sharp edges and seal tube ends.
  2. Coat welds, inside corners, cut edges and tube ends before broad surfaces; use a low-voltage touch-up pass where necessary.
  3. After installation cuts, use a compatible repair system and prevent rainwater from entering tube cavities.
Validation Focus
  • Minimum film thickness at welds/sharp edges
  • Scribed salt spray
  • Tube-end sealing
  • Intercoat adhesion