Case Study: Corrocoat protects Dam Spillway Gates

Corrosion protection for Australian spillway gates.

Client

Water industry, Australia.

Application Date

1995 & 2004.

Scope Of Work

Replace original coal tar epoxy coating.

Products

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

Substrate

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 meters 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.

Photographs

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