Essar Projects, Hazira, Gujarat
Zinc metallizing was carried out on a coarse screen project at a power plant. Essar recorded that the work was completed within schedule and that the quality of workmanship was excellent.
Thermal Spray Zinc Coating Services
Zinc metallizing gives structural steel the sacrificial protection of galvanizing, without the bath, the heat or the size limitation.
- IS 5905 · IS 6586 · BS 5493
- 175–200 µm standard
- Zinc and zinc-aluminium 85/15
How Thermal Spray Zinc Protects Steel
In thermal spray zinc coating, also known as spray galvanizing or zinc metallizing, zinc wire is melted in an electric arc or a flame and atomised by compressed air onto steel that has just been abrasive blasted. The droplets flatten and lock into the blast profile, building a dense zinc layer pass by pass.
Zinc is anodic to steel. Where the coating is scratched or cut, the zinc corrodes first and protects the exposed steel around it. This is the same electrochemical protection that hot-dip galvanizing provides, applied cold and at any size.
Mythri Metallizing has applied zinc and zinc-aluminium coatings since 1999, on fabrications at our Peenya and Dabaspet units and on structures at client sites.
When to Specify Thermal Spray Zinc
Structures Too Large for a Galvanizing Bath
Long girders, tanks, towers and plant structures that cannot be accommodated in a hot-dip kettle can be sprayed in one piece.
Components Liable to Distort in Hot-Dip Galvanizing
The steel remains cool during spraying, so thin sections and welded fabrications retain their shape and tolerances.
Structures Already Installed
Our teams blast and spray in situ, which allows a structure to be protected without being dismantled.
Steel to Be Painted Afterwards
A sealed zinc coating provides an excellent base for paint and extends the life of the paint system applied over it.
Specification
Thickness, sealer and any paint system are agreed for each project on the basis of the service environment and the design life.
- Surface preparation
- Abrasive blast to ISO 8501-1 Sa 2½ or Sa 3, with a sharp anchor profile
- Coating material
- Zinc wire, 99.95% purity to IS 209, or zinc-aluminium alloy 85/15
- Application
- Electric arc or flame spray, within hours of blasting
- Standard thickness
- 175–200 µm, measured before release; up to 500 µm possible
- Standards
- IS 5905 · IS 6586 · BS 5493
- Thickness test
- Calibrated gauge with test pieces, to IS 3203
- Adhesion tests
- Pull-off to ASTM D4541 and scribe test to IS 5905
- Sealer
- Applied over the zinc to close porosity and smooth the surface
- Where
- At our facilities in Bengaluru or at your site
Our Application Procedure
Blast
Compressed-air abrasive blasting removes rust, mill scale and old coatings, and leaves the profile that the zinc requires for a secure bond.
Spray
Zinc wire is melted and atomised onto the fresh surface in overlapping passes until the specified thickness has been built.
Seal
A sealer fills the pores in the sprayed layer, slows the rate at which the zinc is consumed and keeps the surface easy to clean.
Test and Record
Thickness is gauged across the surface and adhesion is tested. The results are entered in the project record and the test certificate.
Applications
Thermal spray zinc protects steel in most atmospheres and in contact with many natural and industrial substances. We apply it for chemical, fertiliser, refinery, cement and power plants, and on buildings, bridges and pipelines.
- Structural steel and building frames
- Transformer tanks and radiators
- Communication and wind-mill towers
- Steel storage tanks
- Electric poles, gates and grilles
- Gutters and structures in chemical plants
- Dairy coils
- Bridges and pipelines
Recent Projects
Frequently Asked Questions
How does thermal spray zinc differ from hot-dip galvanizing?
Both protect steel with zinc. Hot-dip galvanizing immerses the part in molten zinc, so it is limited by the size of the bath and heats the steel. Thermal spray zinc is applied cold with a spray gun, so there is no size limit and no heat distortion, and the work can be carried out on site.
What thickness do you apply?
Our standard is 175–200 µm, measured with a calibrated gauge before the project is released. Thicker coatings, up to about 500 µm, can be applied where the environment requires them.
Can the zinc coating be painted?
Yes. A sealed thermal spray zinc coating provides an excellent base for paint. Paint over metallizing is often specified for appearance or for additional life in aggressive environments, and we can apply the complete system.
Can zinc be sprayed at our site?
Yes. Our teams travel with blasting and arc spray equipment and work on structures in place, in addition to parts brought to our facilities in Bengaluru.
Do you provide test certificates?
Yes. Each project is tested for thickness and adhesion, and the results are recorded. On request, a certificate of zinc wire purity from an external laboratory can be provided with our test certificate.
Send a Drawing for a Metallizing Quote
Share the drawing, the coating you need (zinc or aluminium, and the thickness) and where the steel is. One of our engineers will reply with the method and a quotation.
- Reply within one working day
- Drawings kept confidential
- Email acknowledgement
Thank you. Your enquiry has been received.
One of our engineers will contact you to discuss the requirement. A confirmation has been sent to your email address.