Costs and Economics
The true cost of protecting steelwork from corrosion has to take into consideration two important elements:
1. The initial cost of protection
2. The lifetime cost, which includes the cost of maintenance. This is the cost of ensuring that steelwork is protected from corrosion throughout its service life.
Hot dip galvanizing is often perceived to be more expensive than it is. There are two reasons for this: Firstly, that such a high performance coating is automatically assumed to be expensive. Secondly, the initial cost of galvanizing relative to paint has changed significantly over recent years. Painting costs have steadily increased whilst galvanizing costs have remained stable.
Galvanizers Association recently commissioned independent consultants, The Steel Protection Consultancy Ltd (SPC), to investigate the cost competitiveness of galvanizing. SPC in conjunction with consulting engineers, WS Atkins, designed a typical, 240 tonne, steel-framed building and sent it out to tender. Two corrosion protection systems were specified; (i) hot dip galvanizing and (ii) a good quality, grit blast and three coat paint system of 250µm dry film thickness. Quotations from eight fabricators in different parts of the UK were obtained and averaged. The paint system was found to be 35% more expensive than hot dip galvanizing.
The graph illustrates that for many applications the cost of hot dip galvanizing is lower than that of applying alternative coatings. The reason for this is simple: alternatives such as painting are very labour intensive compared with galvanizing, which is a highly mechanised, closely controlled, factory process.
Comparison between initial costs