The results of these tests are included in Tables II a and II "b of 

 Appendix A. These results show the flame-sprayed zinc coating to 

 compare favorably with other high ranking coatings in the test except 

 in the splash zone. Later tests of longer duration showed a number of 

 other coatings to be quite superior to bare flame-sprayed zinc for pro- 

 tecting steel in seawater. The poor performance of zinc in the splash 

 zone is probably due to the tendency of splashing water to erode the 

 protective corrosion film formed on its surface. Figure 10 shows that 

 the corrosion of zinc in seawater increases with water velocity at least 

 within the velocity range of the test (Tuthill and Schellmoller , I965). 



Other tests involving steel panels coated with flame-sprayed zinc 

 which were exposed by total immersion in seawater at mean tide level, 

 and in the atmosphere, have been carried out at various locations by 

 the American Welding Society (1962). It was concluded from these tests 

 that flame-sprayed zinc coatings 3 mils in thickness exposed alternately 

 to seawater and atmosphere will give less than 6 years of corrosion 

 protection to steel, also that a 6-mil flame-sprayed zinc coating may 

 give little more than 6 years of protection to steel exposed in the same 

 manner. A later, 12-year report by the American Welding Society (196T) 

 which gives results of a continuation of tests of totally immersed panels 

 shows that flame-sprayed zinc coatings of 3 and 6 mils thickness have 

 failed completely. Flame-sprayed zinc with thicknesses of 9, 12, 15 and 

 18 mils was still protecting the steel, however, the zinc was almost 

 entirely coverted to corrosion products. Exposure at mean tide level 

 produced similar results. The results of testing flame-sprayed zinc 

 panels sealed with vinyl and chlorinated rubber are given in this section 

 under "Vinyls" and "Chlorinated Rubber". 



One paper (Horvick, 196^4) suggests that for protecting steel con- 

 tinually immersed in low velocity seawater, under normal conditions, 

 one mil of zinc coating should be specified for each year of protection 

 required. 



Steel panels with a flame-sprayed zinc coating were tested by alter- 

 nate immersion and extraction at quarter-hourly periods in a solution of 

 20 grams of sodium chloride per liter of water for 2,390 hours (Orlowski, 

 1965). The thickness of these zinc coatings were in the order of 1.5, 3 

 and 5 mils. Some were sealed by cold phosphatization. A report on these 

 tests states that: 



1. There was no appearance of rust. 



2. There may be a slight advantage resulting from sealing 

 the zinc coatings by cold phosphatization. 



3. The adhesion of vinyl paint to phosphatized paint is 

 satisfactory. 



Recent test results (Alumbaugh and Brouillette, I966) report flame- 

 sprayed aliiminum tobe far superior to flame-sprayed zinc in protecting steel 



