Corrosion protection for steel structures in buildings

OBJECTIVE/SCOPE

To expand lecture Factors governing protection of steelwork, providing young architects and engineers with guidance on using the information on the protection of steelwork in buildings.

SUMMARY

This lecture discusses the practicalities of design and how to deal with connections (fasteners) and welds. It covers the effects of the environment on the external steelwork of buildings and suggests protective treatments. Common internal environments are discussed. Hidden steel and steelwork in perimeter walls are dealt with separately.

The lecture ends with 'special cases', i.e. steel in concrete and hollow sections.

1. PRACTICAL DESIGN

General considerations, the benefits of designing to allow the effective use of protective coatings, and making a conscious decision as to where they should be applied are dealt with in Section 2 of the lecture Factors governing protection of steelwork. The requirements of Eurocode 3 [1] are described in Appendix 1.

Corrosion prevention truly starts on the drawing board. Design details which avoid water traps, ensure adequate drainage, and promote air circulation restrict corrosion. Avoiding contact between dissimilar metals and removing sharp edges and corners are all important. Supremely important, but frequently overlooked or ignored in design, is access for inspection, cleaning, and maintenance. If the surface cannot be reached, it cannot be maintained.

Design must take into account the required life of the building, the likely time to first maintenance, and the intervals between each subsequent maintenance. The questions to ask when attempting to assess the life requirement of a building are given in Section 1.3 of the lecture Factors governing protection of steelwork.

Connections (fasteners) are an integral part of every structure. Frequently, they appear to be forgotten when the corrosion protection for the steelwork is decided upon. For example, in an aggressive environment, several hundred microns of paint on beams will not effectively protect the structure if it is connected together by black bolts.

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Prerequisites

Introduction to corrosion process

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Factors governing protection of steelwork

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