Client: Costain
Location: Bidston Moss, Merseyside
Project: Refurbishment of the Bidston Moss viaduct
Background
Denholm Industrial Services was contracted to provide multi-discipline services to support refurbishment of the Bidston Moss viaduct. The viaduct was owned by three different public authorities and there were three different paint systems to remove, each with its own challenges.
The Challenge
A number of different coatings had to be removed prior to the application of the new protective coatings, with each one requiring a different approach for correct removal prior. The coating types involved were:
- Conventional epoxy coatings
- Lead based primers
- Thermal metal sprayed zinc coatings
- Wax coatings
- Chlorinated rubber coatings
Our Solution
Thermally sprayed metal coatings are hard and tenacious and full removal requires considerable time and materials. First, we checked that the specified protective coatings to be re-applied were compatible with the existing coatings. Then, the areas in which the existing coating was in good condition were left in place and only the failing areas of metal coatings were removed. This approach was agreed with Costain and written into the project specification.
The wax coatings that had been applied some years earlier presented a surface preparation problem. Attempting to blast wax coatings is mostly unsuccessful, as the abrasive becomes embedded in the soft wax and no longer functions as it should. To overcome this challenge, the wax coatings were firstly removed by hand scraping and solvent washing, prior to conventional blasting.
Due to the lead content of the primers, stringent health and safety control measures were deployed to protect our employees from unnecessary exposure to this toxic material and to comply with the “Control of Lead at Work Regulations”.
Being involved in the project from an early stage enabled effective project planning and Denholm Industrial Services was able to ensure that the risks were mitigated. The project was successfully delivered with zero reportable accidents (AFR = 0.00), ahead of programme and under budget.
