Arc Sprayed Galvanising

Arc Sprayed Galvanising 

With over 20 years experience in the industry, our knowledge of quality products is extensive. We keep up-to-date with the latest technologies in products and work with paint inspectors from various companies to provide quality assurance & technical support on their products.  
Metal spraying offers the following advantages over hot dipped galvanising:
 
  • Sprayed metal systems are the only coating listed in AS/NZ2312 that exceeds 20 years and up to and in excess of 40 years first maintenance.
  • You can design and fabricate without being limited to bath size therefore offers savings in design fabrication and installation.
  • Low heat input during spraying eliminates the risk of bending and twisting and distortion.
  • Longer life possible provides up to 3 times the amount of zinc.
  • More uniform finish no tags or sharp bits.
  • Low heat input eliminates the risk of thermal metallurgical degradation
  • Sealed hollow fabrications may be treated without risk of explosion
  • The process is not limited to zinc. The coating material may be selected specifically for environment.
  • Coating thickness may be varied to provide extra protection.
  • Organic paint coatings adhere well, does not require de-greasing etch priming or a sweep blasting paint to stick.
  • Articles can be treated on site.
  • Arc sprayed galvanising is used to restore corrosion protection on damaged areas of welded galvanised steel.
Industrial equipment for Arc Sprayed Galvanising
Industrial equipment for arc sprayed galvanising

Architectural and Design Specification Service 

Even though an alternative process may have been initially specified for corrosion control, Thermion metalspraying is often the most suitable process for the specific situation. For example, sections of steelwork which are too large to fit into a hot dip bath, may be prone to bending, or the paint system specified may be insufficient for the environment. In these cases, metalspraying might be more appropriate. See our table below for the life expectations of metalsprayed coating systems.
Sandblaster providing sandblasting services
Professional providing Thermion Zinc Metalspraying services
Professional providing thermion zinc metalspraying services

Example Specification for Thermion Zinc Metalspraying

  1. Abrasive blast to class 2.5 as defined in AS 1627-4 with an angular profile of 50 to 100 microns before any deterioration of the cleaned surface occurs, apply 100um zinc metalspray by the Thermion arc spray process. (640 grams of pure zinc metal per sq.mtr hot dip galv normally achieves 610 grams of zinc) measured by AS 3894.3-1993 with a maximum surface roughness of the sprayed metal of 50um.
  2. The specified metal to be sprayed shall be 99.99% zinc in wire form only of a minimum diameter of 3.2mm.
  3. Validate adhesion of the sprayed metal to the steel surface using a suitable bend test e.g. American Welding Society ANS/AWSC 2.18.93.
  4. Seal the zinc metalspray surface before leaving the protective coatings workshop and before any deterioration of the sprayed zinc occurs with Thermion arc spray sealer until absorption ios complete.
  5. If required for decorative reasons apply a finish coat of paint to a nominal thickness of 50 to 75 microns DFT over clean dry sealed sprayed zinc. (The sealed zinc metalspray will not require etch priming and degreasing unlike hot dip galvanising.)
  6. Note 1: The durability of zinc metalspraying can be increased by increasing the thickness of the sprayed zinc, see chart above.
Note 2: The sealer is not intended to be a finish coat of paint. Its purpose is to fill the porosity of the sprayed zinc thereby limiting the amount of zinc exposed to the environment which extends the life of the coating.
Note 3: When powder coating on top of zinc metalspray a sealer if the appropriate type can be used, on that will resist the temperatures of powder coating.
System gm/sqm/side Moderate Marine Severe Marine Offshore Severe Industrial Tropical
ZN100 640 40+ yrs 15-25 yrs 5-15 yrs NR 15-25 yrs
ZN175 1125 40+ yrs 25-40 yrs 15-25 yrs NR 25-40 yrs
ZN250S 1607 40+ yrs 25-40 yrs NR 40+ yrs
AL150S 40+ yrs 25-40 yrs 15-25 yrs 15-25 yrs 25-40 yrs
AL225S 40+ yrs 25-40 yrs 25-40 yrs 40+ yrs
Legend: 
ZN = Zinc 99.99% (or 85/15 = Zinc 85% Aluminium 15%)
AL = Aluminium 99.5% (or AlMg5 = Aluminium 95% Magnesium 5%)
100 to 250 = thickness of sprayed metal microns
S = Sealer
NR = Not Recommended
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