(Ref 11), thin preservatives formulated to penetrate galvanized steel 

 guy lines provide only temporary protection, especially if applied after 

 weathering of the guy lines. A petrolatum paste which encapsulates the 

 guy line to provide a protective barrier seems more practical. CEL and 

 the Naval Radio Station (I), Cutler, Maine (Ref 12), developed equipment 

 (Figure 11) for the remote cleaning and coating of large diameter (1 to 

 3-1/4 inches) guy lines with petrolatum paste. A nylon brush (Figure 12) 

 was used for cleaning the line on the ascent (Figure 13) and coating on 

 the descent. This equipment is still performing very satisfactorily at 

 Cutler, Maine. 



Fiberglass-reinforced epoxy rods (Figure 14) are frequently used on 

 circularly disposed (Wullenweber) arrays (Figure 6) or other systems 

 where high dielectric strength, high tensile strength, and low elonga- 

 tion are required. If their protective coating is lost by weathering 

 and the glass fibers are exposed, a loss in strength can result. It is 

 normally a better investment to replace than recoat such deteriorated 

 rods. Also, the weakest component is the end connector (Ref 13); there- 

 fore, protective coatings are especially important in this area. 



COST CONSIDERATIONS FOR NEW STEEL CONSTRUCTION 



Although life cycle coating costs associated with steel antenna 

 towers vary widely with antenna design, remoteness from populated areas, 

 and severity of environment, some conclusions can be made of the cost 

 effectiveness of different coating procedures on new construction. On 

 existing structures, coating maintenance procedures are largely deter- 

 mined by the type and condition of existing coatings. Reference 7 

 provides much practical information on the repair of existing coatings. 



Surface preparation and priming of steel tower components is best 

 done in a fabrication shop under controlled conditions. This results in 

 a better quality product and reduces costs, even if touchup of damaged 

 coatings is required in the field before erection of the tower. In 

 Table 8 surface preparation and primer costs in a fabrication shop are 

 compared to those in the field*. Costs of surface preparation and 

 priming are much higher after tower erection (at least double on high 

 towers) . 



Initial costs may be deceiving. Table 9 lists available cost data 

 for five coating systems appropriate for antenna towers. Although the 

 alkyd system is the cheapest of the five, it will ordinarily provide the 

 shortest protection in a severe environment. Table 10 lists typical 

 costs and service lives of these five coating systems in an industrial 

 environment. It can be seen that in such moderate or in severe environ- 

 ments, the alkyd system would be the least cost effective. 



In selection of a coating system for new construction, ease and 

 cost of coating maintenance should be of great importance. A zinc-rich 

 system will usually be the most cost effective if the zinc-rich primer 



r If permitted. 



