Special Vehicles

Chemical and outdoor protection for specialised service conditions

Special vehicles include body and chassis components for fire engines, ambulances, tankers and similar vehicles. They must withstand chemical contact, changing outdoor climates and demanding emergency-service conditions, placing strict requirements on chemical-corrosion resistance and weatherability.

Veri Coating offers smooth pure epoxy and high-durable polyester-HAA powder coatings with GT0 adhesion, 100% solids and no solvent, 1,000-hour salt-spray resistance and 480-hour humidity resistance without blistering or delamination.

Application notes: Edge coverage should be checked carefully on complex welded parts, with a recommended film thickness of 60-80 um.

Typical Powder Coating Challenges for Special Vehicles

Concrete Adhesion and Difficult CleaningAdherent concrete residue requires lower surface adhesion and better wash resistance.

Concrete Adhesion and Difficult Cleaning

Mixer drums and related parts are continuously exposed to cement slurry, muddy water and alkaline media. Concrete adheres more readily when the coating is rough, has high surface energy or is insufficiently crosslinked. Repeated high-pressure washing then accelerates gloss loss, wear and local delamination.

Formulation Design

  1. Use a weatherable polyester system and reduce cement-slurry adhesion by controlling resin acid value, melt flow and surface orientation.
  2. Control wax or slip-additive loading to improve surface slip and cleanability without impairing intercoat adhesion.

Process Control

  1. Grind and dress welds, blowholes and weld spatter before coating to ensure a continuous pretreatment layer.
  2. Control film thickness and degree of cure; local undercure, orange peel or roughness increases contaminant retention.
  3. Validate repeated adhesion-and-rinse cycles with the actual concrete slurry rather than water alone.
Validation Focus
  • Concrete pickup and residue after cleaning
  • Alkali resistance and appearance after damp heat
  • Adhesion after high-pressure wash cycles
  • Change in surface gloss and abrasion
Weld Coverage and Localised Corrosion FailureLow powder deposition at welds requires stronger cleaning, touch-up and corrosion-protection measures.

Weld Coverage and Localised Corrosion Failure

Weld areas often contain mill scale, slag, oil, porosity and geometrical recesses. Inadequate pretreatment weakens adhesion, while the complex electrostatic field reduces powder deposition, causing pinholes, exposed substrate or local corrosion spread around welds after salt-spray exposure.

Formulation Design

  1. Select an epoxy powder primer with good wetting and adhesion on steel, and optimise particle size, flow and thixotropy to improve powder hold on welds.
  2. Use a two-coat system of epoxy powder primer and weatherable polyester topcoat in highly corrosive areas.

Process Control

  1. Remove slag, mill scale and oil completely. Dress blowholes and other substrate defects first; use filler only after coating-system compatibility has been validated.
  2. Pre-coat or touch up welds, inside corners and shadowed areas, and confirm the recoat window between primer and topcoat.
  3. Preheat castings or heavy welded parts before coating to remove moisture and reduce pinholing and blistering.
Validation Focus
  • Weld cleanliness and pretreatment continuity
  • Film thickness and pinholes at welds
  • Primer-to-topcoat adhesion
  • Neutral salt spray or cyclic-corrosion performance