INTRODUCTION 



Many Navy antenna towers are located in remote locations where 

 maintenance facilities are limited and severe environment, such as 

 marine or tropical exposure, causes rapid, localized, coating damage. 

 The heights and configurations of these towers permit only steeplejacks 

 or repairmen utilizing an aerial-serving platform to reach all areas. 

 Even then, some areas are frequently hard to reach. Repair of damaged 

 coatings by conventional means (e.g., sandblasting and spray painting) 

 is very costly and, in some cases, impossible because of physical limi- 

 tations or environmental regulations. Dry abrasive blasting, for example, 

 is frequently restricted because of particulate emission. Thus, the 

 Civil Engineering Laboratory (CEL) was directed by the Naval Facilities 

 Engineering Command to develop optimum methods for in-place repair of 

 damaged exterior antenna coatings. 



Reference 1 describes initial laboratory and field studies on 

 antenna coating repair materials and methods. This technical note is 

 the second and final document of the investigation, which included: 

 (1) accelerated, salt-spray testing of experimental and specification 

 coating systems; (2) results of 3 years of field testing of candidate 

 materials from accelerated tests on an antenna positioner at the Pacific 

 Missile Test Center (PMTC) , Point Mugu, Calif.; (3) development of 

 cleaning and coating techniques and equipment; (4) testing of developed 

 coating systems and cleaning and coating techniques and equipment on two 

 vortex towers in a very corrosive environment at PMTC; and (5) a summary 

 of currently recommended practices for protecting antenna towers from a 

 corrosive environment. 



BRIEF DISCUSSION OF FIELD TEST ON ANTENNA POSITIONER AT PMTC 



Reference 1 provides detailed information on the application and 

 initial ratings of 32 coating systems (all consist of one coat of primer 

 and one coat of topcoat) on an antenna positioner located at the lagoon 

 area at PMTC. Monthly ratings were made for a total of 3 years, at the 

 end of which, 19 of the 32 systems were providing good protection to the 

 steel. As far as is possible, ASTM photographic standards were used to 

 rate these specimens. Table 1 lists coating conditions after years of 

 exposure. 



Ratings at the end of 3 years for various properties generally 

 ranged from a high of 10 (perfect) to a low of 0. Heavy chalking, 

 common to all exterior epoxies , occurred with all the experimental 

 coating systems. However, this condition does not result in loss of 



