75820 TDGAllied Bolt announces the launch of Thermal Diffusion Galvanized Poleline Hardware. Allied Bolt’s thermal diffusion galvanizing (TDG) conforms to the ASTM Specification A 1059-08 (2013) “Standard Specification for Zinc Alloy Thermal-Diffusion Coatings (TDC) on Steel Fasteners, Hardware, and other products.”

A description of the TDG process can be found in the standard: “This specification covers the general requirements for protective zinc coatings to be applied by the thermal-diffusion coating (TDC) method. To various products made of carbon steel, including low and high tensile parts as well as of wrought iron, sintered iron steel-powder and various steel and stainless steel alloys. TDC is carried out by immersing the parts in a zinc alloy powder at elevated temperature for a period of time, causing a metallurgical diffusion process of zinc and iron. Further processing may be added such as, passivation, topcoat application, paint application, etc.”

Uniform coating thickness, even on threaded areas of fasteners, make this process very desirable. Compared to the hot-dip galvanizing process, the coatings are more corrosion resistant. The process does not involve the formation of hydrogen, making the parts immune to hydrogen embrittlement.

The salt spray test per ASTM B117 has received the widest acceptance as a tool evaluating and predicting the longevity of hardware in the field. Allied Bolt uses the GreenkoteTM (Brook Park, Ohio) process of TDG along with their proprietary top coat to ensure 2,500 hours salt spray without significant signs of red rust. Below please find a comparison of hot dip galvanized hardware to Allied Bolt’s TDG Hardware.

Click here to download PDF of the Test Report.