Corrocoat protects spillway gates

Corrosion protection for australian spillway gates.

Scope of work

Replace original coal tar epoxy coating.


Upstream submerged areas: Polyglass VEF
Downstream submerged areas: Polyglass Zipcoat
Rubbing areas: Plasmet HTE
Normal atmospheric exposure areas: Plasmet ZF


Mild steel & cast iron fabrication

Application method

Grit blast to ISO 8501-1 cleanliness std SA 3
Polyglass VEF applied at 1000μm DFT
Polyglass 100 Zipcoat applied at 1000μm DFT
Plasmet HTE applied at 2000μm DFT
Plasmet ZF applied at 400μm DFT

Coating credentials

Access to the gates is difficult and expensive being 80 metres above the river bed, so long term corrosion protection is highly desirable for this asset with a required life of 200 years. Despite the use of established coatings and reputable painting contractors, early coating breakdown was recorded in the first couple of years of the gate re-painting program. Corrocoat Engineering Victoria offered a 10 year warranty with an expected life of 30 years. In 1995, Corrocoat was requested to refurbish three gates as a result of a life cycle cost-benefit comparison exercise, between a combination of Corrocoat systems and other lower cost epoxy resin systems. Corrocoat was awarded the work for 3 gates, and it was carried out successfully, in the middle of winter, with the gates being put back into operation on time. Inspections in 2004 have revealed that whilst further deterioration of the epoxy resin / coal tar epoxy coated gates is evident, no such deterioration of the three gates coated using Corrocoat’s system was noted by the delighted customer, with the equipment remaining in excellent condition.


The spillway gates at Glenmaggie and access to the gates was the first hurdle for Corrocoat
One of the spillway gates after coating – note the complex geometries
Visual inspection of one of the gates after service – showing no coating breakdown.