Bubbling during the fabrication of trough-type cable trays

Bubbling during the fabrication of trough-type cable trays is typically caused by improper surface preparation, trapped moisture, or coating defects during galvanization or painting.

Causes of Bubbling

1. Surface Contamination: Oil, grease, or dirt on the metal surface can prevent proper adhesion of coatings, leading to bubbles when the tray is hot-dip galvanized or painted .
2. Trapped Moisture: Residual water or humidity on the tray surface can vaporize during heating, forming bubbles under the coating layer .
3. Improper Coating Application: Uneven zinc coating during hot-dip galvanization or insufficient curing of paint layers can create localized bubbling .
4. Material Defects: Variations in steel or aluminum alloy composition, such as impurities or inconsistent thickness, can contribute to bubbling during thermal processes .

Prevention Measures

• Thorough Surface Cleaning: Ensure all metal surfaces are free from oils, rust, and debris before coating or galvanizing .
• Controlled Drying: Dry the trays completely to remove moisture before hot-dip galvanizing or painting .
• Proper Coating Techniques: Follow manufacturer guidelines for zinc bath temperature, immersion time, and post-treatment to avoid coating defects .
• Repair Damaged Areas: Any cuts or scratches after galvanization should be treated with compatible zinc-rich paint to maintain coating integrity .

Impact of Bubbling

Bubbling can compromise the corrosion resistance of the tray, reduce aesthetic quality, and potentially affect structural integrity if severe. In outdoor or corrosive environments, even small bubbles can become initiation points for rust or pitting .

Recommendations

• Work closely with the manufacturer to ensure proper fabrication and coating standards are followed.
• Inspect trays after galvanization or painting for early signs of bubbling.
• Use ventilated or perforated trough designs to reduce trapped moisture during fabrication and installation . By addressing surface preparation, moisture control, and coating application, bubbling during the fabrication of trough-type cable trays can be minimized, ensuring long-term durability and performance.