What is Film Galvanisation
While hot dip galvanizing coats iron and steel by immersion into molten Zinc bath, ‘Cold Galvanizing’ is the process of painting steel structures and exteriors with Zinc – rich paints. “Cold galvanizing” or Zinc painting is the application (by brush or spray) of Zinc dust mixed with organic or inorganic binders. Commonly containing 92-95% metallic Zinc in dry film, these Zinc-rich paints can be applied to structural steel and piping which are exposed to a wide range of corrosive atmospheric environments like refineries, power plants, bridges, buildings, mining equipment etc.
With a high percentage of Zinc in the dry film, these paints can synergistically combined with the corrosion inhibitive properties of metallic Zinc. The Zinc dust in paint is integrated with organic binders. These binders allow the Zinc particles to remain in contact with each other so the Zinc paint can provide cathodic protection. While Zinc protects structures from corrosion by hot-dip galvanizing or cold galvanizing, there is high intrinsic value in using both the techniques together, known as a duplex system.
What is Zinga?
ZINGA is a one component zinc rich coating or Film Galvanising System containing 96% zinc (dust) in its dry film. It is a metallic coating and not a paint. The purity of the zinc used, is so high that dry ZINGA does not contain any toxic elements.
ZINGA is a unique form of corrosion protection because it provides both Active and Passive protection in a form that’s as easy to apply as a paint.
ZINGA was originally invented at the University of Ghent (UGent), Belgium, in the 1970s and has since been used in a wide variety of projects throughout the world.
ZINGA is an active zinc performance coating which works in conjunction with the metal beneath, whereas paints are only passive barriers. Regardless of how thick paints are applied, they remain as barriers. Once they are breached, corrosion sets in immediately. Despite this significant difference ZINGA is still often mistaken for a paint simply because it’s liquid and comes in a tin. But there are other more subtle differences. For example it does not “skin over” in the tin because ZINGA has an unlimited pot-life and it doesn’t go “tacky” like a paint.
How does it work?
When two different metals come in contact with each other in presence of an electrolyte (e.g. water), they form a galvanic cell in which the lesser noble metal (e.g. Zn) corrodes in favour of the more noble metal (e.g. steel). This electrochemical reaction is the base for the complex field that is cathodic protection.
Galvanic, cathodic protection, or active protection, arises from zinc (the anode) sacrificing itself in favour of the base metal -steel (the cathode) with the resulting flow of electrons preventing steel corrosion. In this way the protection of the metal is guaranteed, even when the zinc layer is slightly damaged.
Other well-established methods of cathodic protection include hot-dip galvanising (HDG) and zinc thermal spraying, both of which exhibit a constant sacrificial rate of the zinc layer.
With ZINGA the sacrificial rate reduces dramatically after the zinc layer has oxidised and the natural porosity has been filled with zinc salts. Additionally the zinc particles within the ZINGA layer are protected by the organic binder without adversely affecting the electrical conductivity. This enables ZINGA to create nearly the same galvanic potential between the zinc and the steel as hot dip galvanising but with a lower rate of zinc loss because, put simply, the binder acts as a “corrosion inhibitor” to the zinc.
How can it be used?
Stand Alone System :
ZINGA provides comparable protection to conventional galvanising without the need for topcoats. Although ZINGA is only available in grey (the natural colour of zinc), the significant advantage of this form of application is that the ZINGA layer can be re-coated at any point in the future with the bare minimum of preparation and without compromising the integrity of the coating (see Re-charging of ZINGA). ZINGA on its own is often used, because the structure is already on site or too big for the molten zinc baths. Additionally ZINGA is commonly specified on delicate structures (wrought iron gates, sculptures) or when architectural demands require a higher standard of surface finish (no need to drill to de-gas, fettle).
For optimal protection, ZINGA should be applied in two layers of 60 or 90 µm DFT each.
As A Primer in a Duplex & Triplex System :
ZINGA and the topcoats work in harmony to extend the lifetime of the system. As the ZINGA layer will not begin to sacrifice itself until the topcoat is breached, the original zinc thickness is maintained whilst affording the topcoat protection from under-creep and blistering.
In a duplex and triplex system (Active + Passive), ZINGA should be applied in 1 layer of min. 60 to 80 µm DFT.
For more information and application instructions, see ‘Overcoating ZINGA’.
As Shop Primer :
At 30-40 µm DFT, ZINGA can be used as a shop primer. The big benefit is found in the fact that the steel structures do not require reblasting before coating if ZINGA is applied as a shop primer. The steel structure can be overcoated with ZINGA to obtain a cathodic protection or with any other paint without the need for reblasting!
Zinganised steel structures can be welded and bent during assembly.
Repair for worn and damaged Hot-Dip Galvanized or Metal sprayed structures :
This method is probably the most common use of ZINGA as it requires the simplest surface preparation. ZINGA’s mechanism of protection is so similar to conventional galvanizing that they work in complete unison, as they are merely different forms of zinc. Rather than replacing galvanized assets, structures can simply have their protection “re-charged” by applying ZINGA to the rough surface of the old galvanizing after appropriate decontamination of the surface and removal of the salts.
On Rebars :
ZINGA is used globally in the construction industry on steel rebars prior to assembly and immersion as it delivers increased corrosion protection without compromising pull-out strength in even the lowest quality of concretes.
Independent laboratory testing performed by multiple institutes has proven ZINGA can guarantee twice the corrosion protection compared to that of galvanised or epoxy coated rebars.
About John Galt International
Founded in 1978, John Galt International is a Total Quality Management certified heavy engineering company.
Our expertise lies in design, manufacturing and supply of process equipment such as
Storage tanks and bullets, Pressure Vessels and Reactors, Heat Exchangers, Distillation Columns, Boilers
Material Handling Equipment such as E.O.T Cranes, Stackers, Reclaimers and Wagon Tipplers, Conveyors and Frames
We have a 15000 sq meter manufacturing plant in Badlapur, Maharashtra
About John Galt Zinga Technologies
John Galt Zinga Technologies is the authorised all India Distributor of ZingaMetall BvBa. We are the principal importers of Zinga products in India.
Zinga is the market leader in COld Galvanizing.
Mr. R.K. Bhatia is a graduate in Mechanical Engineering and post graduation in Business Management. He has more than 45 years of Industrial experience, starting his career with companies like Larsen & Toubro and Voltas. He has received many recognitions from Industrial Forums for his contribution in the field of manufacturing. He manages operations and finances for the group companies.
Abhay graduated in Computer Engineering in 2007, following which he worked in various roles at John Galt. In 2013, he completed his MBA in General Management and Marketing from the Indian School of Business. Since then, Abhay heads sales, marketing and strategy
Manager, Business Development
Prajwalit is having over 7 years of experience managing business development of leading FMCG companies. He has significant experience in dealer management as well