Nuclear facility benefits from using a composite insert bonded into a pipe to fix its severe corrosion issue

Louise Smyth

Composite repairs and wrap systems are not necessarily a hot topic any more, with many standards, procedures and case studies available on the subject. However, every so often we still come across a story of a simple wrap being used as an ingredient for an unorthodox, well-engineered repair solution.

In 2017, a nuclear power station in France identified a problem at the bottom of a sump pit of its cooling water system. The 200mm ID suction pipe protruding from a concrete wall was experiencing severe corrosion. An externally applied repair was not feasible as corrosion extended well beyond the area encapsulated in concrete. To make matters worse, the flange connecting the pipe to the drain pump was also badly corroded.

Belzona’s distributor in western France, Alliatech, used its experience serving the French market to come up with a unique solution. This solution was designed to solve the problem and prevent any further corrosion for the long term.

When external repair is not an option
A cut-and-weld technique would have caused needless downtime and the extent of metal degradation called for more than a protective lining. For minimum downtime and fast return to service, a repair had to be completed from the inside of the pipe. A durable 500mm long ‘composite insert’ was created using the Belzona SuperWrap II system and a plastic former.

When it came to creating and consolidating the composite insert, a familiar application procedure was adhered to. The procedure followed some of the steps taken for a regular pipe wrap: wetting out the reinforcement sheet with resin; applying the sheet onto the former with 50% overlap; and consolidating the wrap using the release film provided.

The composite insert was created complete with a new flange, 70mm wide and 10mm thick. Once the sleeve was cured and former removed, it was sanded with holes drilled to match those of the original flange.

Composite insert
The next step was to bond the insert into the pipe. After grit blasting, Belzona 1161, a surface-tolerant paste-grade material, was used as an adhesive between the sleeve and the pipe, at a maximum thickness of 10mm.

Finally, to ensure lasting erosion-corrosion protection, Belzona 1321 (Ceramic S-Metal), a 100% solids ceramic protective coating was applied on the inside, outside and around the pipe to prevent any issues from reoccurring.

The future of composite repairs
It is amazing how many problems can be solved with tried-and-tested repair materials. Particularly these days, with a focus on restoring rather than replacing, reducing downtime to a minimum and optimising operating efficiency. Solutions that can adapt to the ever-changing challenges are the future of industrial maintenance.

For more information visit Belzona

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