The Service:
The £185 million Runcorn Thermal Power Station was designed using a unique combination of hot-dip galvanised beams and film-galvanised beams (zinganised beams) as the 66 box-section beams could not be placed into a HDG tank because:- 1. The box-beams would require large holes to be drilled every linear metre for de-gassing
- 2. The potential for distortion when being dipped at 450°C was extremely high, and each beam has 22 mounting holes drilled either end. Even distortion of 2mm would cause tremendous problems during erection.
- 3. If the molten zinc did not drain out of the degassing holes it would have added a great deal of weight.
As the upright HDG beams and the vertical film-galvanised box-beams are both zinc coated with both identical "open-circuit" electrical potentials of 1040mV, there was no danger of any galvanic reactions on any part of the structure.
