Denso chosen for Forth Road Bridge hanger cables

Citation

(1999), "Denso chosen for Forth Road Bridge hanger cables", Anti-Corrosion Methods and Materials, Vol. 46 No. 5. https://doi.org/10.1108/acmm.1999.12846eab.002

Denso chosen for Forth Road Bridge hanger cables

Methods

Denso chosen for Forth Road Bridge hanger cables

Keywords Denso, Bridges, Corrosion prevention, Coatings

Scotland's Forth Road Bridge was opened in September 1964. Twenty years later the Forth Road Bridge Joint Board decided that the bridge hanger should be protected with Winn & Coales Denso Tape. When this was removed in 1996 to permit inspection of the suspenders it is reported that it was found to be still in good condition.

All of the 192 hanger cables (Plate 2) are now being replaced, a pair at a time, and Consultants W.A. Fairhurst have specified that Denso materials will again be used to give long-life protection in this corrosive marine environment.

Plate 2 Close-up of Denso protection of hanger cables on the Forth Road Bridge

McAlpine are general contractors for the project, with Monberg & Thorsen of Copenhagen being responsible for the suspender replacement.

Where the galvanized hanger cables pass over the twin main suspension cables there is a grooved casting to receive the hanger cables. Densyl Mastic is being applied to these grooved areas to give a uniform profile prior to application of Denso Tape down to 300mm from the top. This is followed by Densotherm Tape, a hot applied tape comprising a non-woven fabric carrier coated with a modified bitumen compound.

Winn & Coales state that they are confident that this Denso system will ensure corrosion protection for the Forth Road Bridge hanger cables for the next 35 years.

Winn & Coales' expertise was also called on when Kent County Council Contract Services (the Council's own direct labour organisation) recently completed a strengthening and refurbishment of the road bridge carrying the A257 over the river Bourne at Littlebourne, near Canterbury, UK. The strengthening programme included welding on steel plates to 11 of the structural beams supporting the ragstone and brickwork bridge.

Following shotblasting, all structural steelwork was protected with Winn & Coales Denso Protal S.T. Epoxy Mastic for long-life protection. This was followed by a dark green topcoat to blend in with the environment.

Key benefits claimed for Winn & Coales environmentally responsible Denso Protal S.T. Epoxy Mastic include: exceptional wetting and deep penetration of residual rust; fast curing; high mechanical strength; cost saving due to fewer coats; cures at temperatures as low as -100°C. Also, its exceptional adhesion properties are designed for surfaces which have been hydrojetted or power tool prepared.

Details available from Winn & Coales (Denso) Ltd. Tel: +44 (0)181 670 7511; Fax: +44 (0)181 761 2456.