Water-based solution is right for Thames Barrier

Citation

(2001), "Water-based solution is right for Thames Barrier", Anti-Corrosion Methods and Materials, Vol. 48 No. 5. https://doi.org/10.1108/acmm.2001.12848eab.002

Water-based solution is right for Thames Barrier

Water-based solution is right for Thames BarrierKeywords: Pugh & Co., Primers

It is reported that following successful field trials of an environmentally friendly primer, pipework underneath the Thames Barrier in London will be protected with a highly cost effective, 100 per cent water-based system.

With a claimed VOC content of less than 0.1g/litre, Actan GS – manufactured by Pugh & Co International – is said to be safer, quicker and easier to apply than traditional solvent based primers, especially in enclosed environments.

This water-based primer for treating galvanized and non-ferrous metal surfaces reportedly adheres very strongly to sufaces and protects equally well on new and weathered galvanizing. According to Pugh, Actan GS can be overcoated with a wide range of one and two pack protective paint systems including vinyls, acrylics, epoxies, chlorinated rubbers and polyurethanes.

Nine-month trials on Actan GS were carried out at the Thames Barrier by a UK independent coatings consultancy in conjunction with The Environment Agency – Thames Barrier, which is responsible for the structure.

The trial areas selected were believed to be a tough testing ground for any primer: 18-year-old galvanized pipework in the fire protection drainage system running under the Barrier. The pipework is situated in cool, ventilated tunnels and included some surfaces where there was excessive zinc salt formation and others where the original zinc spangle was still present.

Following only the minimal hand preparation that is necessary, Actan GS was applied by brush. Health and safety risks to operatives using Actan GS is considered by Pugh to be minimal, even in enclosed areas, because it reportedly does not give off harmful fumes or present a fire risk.

Another benefit claimed of Actan GS in planning maintenance programmes is that overcoating time is not critical. At the Thames Barrier trials, one-third of the primer was left without a top coat, one-third was overcoated with water-based Actan T38 and the final third with a vinyl coating from a loading coatings manufacturer.

David Deacon, whose company SPC applied the primer on the trial areas, says: "Actan GS was quick and easy to use – despite some of the pipes being difficult to access as they backed on to walls – resulting in significant labour and cost savings".

All test areas were visually and micro-destructively examined for blistering, loss of adhesion, flaking and detachment properties of Actan GS three and nine months after coating.

"Conventional paints adhere poorly to hot dip galvanized surfaces but the performance of Actan GS was outstanding", says David Deacon, "It was impossible to detach the vinyl topcoat from the Actan GS primer, or the primer from the zinc surface even using a pointed scalpel knife blade without causing considerable mechanical damage to the zinc surface".

Following the trials, SPC recommended Actan GS as the ideal solution to provide necessary protection for both new and weathered galvanizing, with a choice of top coats. The Environment Agency – Thames Barrier has now opted to use Actan GS overcoated with Actan T38 waster-based topcoat, for approximately 80 waste pipes located underneath all nine piers of the Thames Barrier.

Details available from: Pugh & Co International. Tel: +32 2 732 27 77 or Gallotech Ltd. Tel: +44 (0)1937 541270.