Representative samples of Thermal Sprayed Zinc and Hot Dipped Galvanized
ductile iron castings conforming to ASTM2
A 536, Grade 65-45-12, were
subjected to a 5% salt spray fog test at 95 ˚F in accordance with ASTM B 117.
Coating thickness was measured in the range of 3.4 to 5.5 mils for all samples
evaluated, which conforms to the industry requirement for grooved piping
products. An independent laboratory NADCAP accredited in materials and nondestructive
testing methods performed the testing.
After 120 hours exposure, the Hot Dipped Galvanized samples exhibited red
corrosion. The Thermal Sprayed Zinc samples did not exhibit red rust corrosion.
Testing was continued on the Thermal Sprayed Zinc samples for an additional 72
hours for a total of 192 hours and examined for signs of red rust. None of the
Thermal Sprayed Zinc samples exhibited this condition and testing was stopped.