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Typical Protective Coating Specifications

The framework to assess and rank specifications presented in the previous section is based on commonly used specifications to protect structural steel against corrosion in applications such as building, bridges etc.

The following are some typical corrosion protection specifications all based on blast cleaning to Sa 2 of ISO8501-1. For our information, Graham has included suggested service environments and a few pictures illustrating where these specifications have been used.

a) Conventional Epoxy specification

Coat

Material

Thickness (mm)

Primer

Epoxy Zinc Phosphate

75

Barrier

Epoxy MIO

125

Finish

Polyurethane

50

Finish

Polyurethane

50

Standard UK Highways agency specification for use on motorway bridges. Expected life to first major maintenance in excess of 20 years, used on the Blythe Valley Bridge.

b) Zinc rich epoxy specification

Coat

Material

Thickness (mm)

Primer

Epoxy Zinc Rich

40

Barrier

Epoxy MIO

150

Barrier

Epoxy MIO

150

Finish

Polyurethane

50

Bridge specification. Used on Oresund crossing and Channel Tunnel Rail link structures

c) Zinc rich for buildings

Coat

Material

Thickness (mm)

Primer

Epoxy Zinc Rich

75

Barrier

Epoxy MIO

125

Finish

Polyurethane

50

Standard specification for external steel on buildings.

d) Zinc rich only specification

Coat

Material

Thickness (mm)

Primer

Epoxy Zinc Rich

75

Cavity and perimeter steel in buildings

e) Epoxy Phosphate specification

Coat

Material

Thickness (mm)

Primer

Epoxy Zinc Phosphate

75

Barrier

Epoxy MIO

100

Finish

Polyurethane

50

In swimming pool environments. External steel easily maintainable.

f) Alkyd specification

Coat

Material

Thickness (mm)

Primer

Alkyd Zinc Phosphate

40

Barrier

Alkyd MIO

75

Finish

Alkyd undercoat

75

Finish

Alkyd Gloss

50

g) Glass Flake Epoxy (GFE) specification for bridges

Coat

Material

Thickness (mm)

Primer

Epoxy Zinc phosphate

25

Barrier

GFE

400

Finish

Polyurethane

50

h) Glass Flake Epoxy (GFE) specification for offshore platforms

Coat

Material

Thickness (mm)

Primer

Epoxy Zinc phosphate

25

Barrier

GFE

500

Barrier

GFE

500

Finish

Polyurethane

50

This document was prepared on 10 November 2000 by Graham Gedge