Is galvanised hardware on your network letting down your asset performance?

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Benefit from enhanced corrosion protection for line hardware and substation components with TDG, which offers superior steel protection, is less harmful to the environment, and costs less than stainless steel.

Do you have corrosion problems in line and substation hardware that is prematurely limiting the life of your electrical equipment?

Metal corrosion on galvanised parts and equipment – particularly in coastal areas – is a significant problem on network assets. The lifespan of Hot Dipped Galvanised parts is typical 5-15 years, which is generally significantly less than the mechanical life expectancy of the parts or equipment.

Inspection, maintenance and preventive measures are limited in application and have marginal results in prolonging the coating protection on metal surfaces.

The generally accepted alternative to HDG for parts that are severally corroding is to use stainless steel – with an obvious downside of the significant cost premium incurred.

Thermal Diffusion Galvanising

Thermal Diffusion Galvanising has been around for a little while but is now becoming available on line hardware components. TDG is a method of applying uniform, sacrificial, zinc iron alloy coating using a metallurgical vapour infusion process. Applied by tumbling metal parts within a patented zinc powder in a cylinder which is slowly rotated inside an oven at around 427˚C (800˚F) for two hours. The zinc iron alloy is infused into the surface of the metal, including into the threads on bolts and nuts, as opposed to the HDG process which lays a coating on the surface.

TDG has significant benefits over Hot Dipped Galvanising, including:

• significantly lower environmental costs in the manufacturing/coating process
  • virtually zero waste process
  • acid free service preparation (no pickling acid)
• TDG extends the life of steel components by up to 10 times
• TDG has a more uniform coating thickness and no hydrogen embrittlement
• TDG increases surface hardness, therefore it is more abrasion resistant
• TDG can be painted over

TDG is a cost effective solution for metal parts in medium to high corrosion situations. Value as shown below is derived from longer life for the part or component, with performance comparable to SS304.

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Testing results after 3000 hours in salt fog shows the significantly superior performance of TDG over HDG.

(Left, HDG after 3000 hours in salt fog; Right, Armorgalv® after 3000 Hours in salt fog)

In summary, line hardware and steel components (e.g. fasteners) which are treated by the TDG process instead of Hot Dipped Galvanising have a significantly longer life and are manufactured with a much lower environmental cost. TDG treated steel has a harder, more uniform and more durable protection layer. In salt fog performance testing, TDG is approximately 10 times better than HDG and is approximately equal in corrosion prevention performance to stainless steel.

Do you want to discuss opportunities to reduce line hardware life time costs?

For more information on what range is available in TDG please contact:

Bruce Blundell
P: +64 9 274 4280
M: +64 21 427 774
E: bruce.blundell@acculec.co.nz