Thermal Spray Metallizing (Zinc, Aluminum, Zinc-Aluminum)

What we metallize

Metallizing protects steel with a layer of zinc, aluminum or zinc-aluminum alloy, melted and sprayed onto a blasted substrate. The sprayed metal acts as a barrier and, for zinc and its alloys, as a sacrificial anode: it corrodes instead of the steel at scratches and edges. It is one of the options within our industrial and protective coatings, our core business.

• Bridges and civil structures: girders, bearings, areas exposed to de-icing salts (bridge painting).
• Steel structures: frames, walkways, conveyors and supports in industrial or coastal settings (steel structure painting).
• Towers, masts and poles: power lines, telecommunications, lighting.
• Equipment: hoppers, stacks, outdoor tanks, parts too large for a galvanizing bath.
• Steel under insulation: insulated piping and vessels, with thermal spray aluminum (TSA).

The service is for industrial sites and public infrastructure only, not residential. Work is carried out by our crews and qualified subcontractors.

Zinc, aluminum or zinc-aluminum: choosing by environment

The metal is chosen from the exposure environment and the planned finish system. ISO 2063-1 sets the design rules and designates the metals (Zn, Al, ZnAl15, AlMg5, among others); SSPC-CS 23.00 / AWS C2.23 / NACE No. 12 covers the same families for steel.

• Zinc: strong galvanic protection, a good choice in industrial and urban atmospheres, on bridges and towers, and where touch-ups are expected.
• Aluminum: a more stable layer in marine and splash zones, in immersion in some waters, and under insulation. Its galvanic protection is weaker than zinc's.
• Zinc-aluminum: an alloy that keeps part of zinc's sacrificial action and adds aluminum's stability, often chosen for coastal or salt-laden atmospheres.

Target thickness, sealer and finish depend on the metal and the environment. They are set from the tables in ISO 2063-1 and SSPC-CS 23.00, the site's ISO 12944-2 corrosivity category and the wire data sheet.

Under insulation, thermal spray aluminum (TSA) is one of the options listed by AMPP SP0198 for insulated carbon steel: it withstands thermal cycling and water trapped under the insulation, where many paints blister. The allowed temperature range and the sealer are taken from that practice and from the sealer data sheet. Our article zinc vs aluminum thermal spray covers the comparison in detail.

Arc spray or flame spray

Electric arc suits large areas; flame suits small parts, touch-ups and places where power supply is difficult. Both processes are covered by ISO 2063-2 and SSPC-CS 23.00.

• Arc spray: two metal wires melted by an electric arc, then atomized with compressed air. High deposition rate, good adhesion, suited to girders, towers and large frames.
• Flame spray: one wire melted in a fuel gas and oxygen flame. Lighter equipment, useful for details, repairs and remote sites.

In both cases the steel stays cool: no distortion as in a molten zinc bath, and no limit on part size. The operator and the process are qualified on coupons before the job, as the standards require.

High-grade surface preparation, sealer and duplex systems

Metallizing does not tolerate average preparation: the steel must be blasted to white or near-white metal with an angular abrasive. SSPC-CS 23.00 refers to SSPC-SP 5 / NACE No. 1 or SSPC-SP 10 / NACE No. 2; ISO 2063-2 refers to Sa 3 or Sa 2½ under ISO 8501-1. Abrasive blasting creates the minimum angular profile these standards require (surface profile).

• Clean, dry angular abrasive: round shot does not give the required anchor.
• Spraying soon after blasting, before any rust or condensation.
• Surface above the dew point, with the margin the standard sets.

Sprayed metal is porous. A penetrating sealer closes the pores and slows the consumption of the metal; ISO 2063-1 and SSPC-CS 23.00 recommend it in most environments. A duplex system adds one or more compatible paint coats on top, for color, UV resistance or a harsher environment. The full system is selected with each product's data sheet.

Inspections and standards

Each layer is inspected and recorded in the file, from preparation to sealer.

• ISO 8501-1 and SSPC-SP 5 / SP 10: blast cleanliness grade before spraying.
• Thickness: magnetic gauge readings under SSPC-PA 2 and ISO 2063-2, checked against the specified minimum.
• Adhesion: tensile pull-off test under ASTM D4541, at the frequency set by the standard or the specification.
• Bend test: witness coupons bent around a mandrel, as SSPC-CS 23.00 requires; the layer must not spall or lift.
• Job reference standard (JRS): a witness area sprayed at the start of the job under SSPC-CS 23.00, used as the benchmark for appearance and thickness.

Our coating inspection service can carry out these checks independently if the owner asks.

In the shop or on site, and site conditions

Transportable parts are metallized in the shop, at our subcontractor's facility; structures in place are metallized on site, inside an enclosure. The choice depends on part size, transport and the shutdown window.

• In the shop: stable conditions, blasting in a booth, steady pace; parts come back sealed or ready for finishing.
• On site: closed enclosure, dehumidification and heating as needed, recovery of abrasive and metal dust.
• Metal fumes: ventilation, extraction and respiratory protection, since zinc fume can cause metal fume fever.
• Arc and flame: UV eye protection, hearing protection, gas cylinder handling and hot work permits.
• Confined spaces and height: entry permit, attendant, harness and rescue plan.

Provincial occupational health and safety rules and site rules apply at all times.

Pricing: by quote

Metallizing is priced by quote. Six factors drive it:

• Area and shape of the parts: a plain girder goes faster than a lattice tower.
• Substrate condition and the coating to remove before blasting.
• The metal chosen, the target thickness and the process (arc or flame).
• The sealer or the duplex finish system.
• Location: in the shop with transport, or on site inside an enclosure.
• Access, season and work window.

Send photos, approximate dimensions and the location with your quote request: we reply within 24 business hours.

Where we work

Induscoat provides thermal spray metallizing across Quebec and in Ontario, working from LaSalle, Montreal:

• Montreal and Montérégie
• Quebec, for the province as a whole
• Abitibi-Témiscamingue
• Côte-Nord
• Saguenay–Lac-Saint-Jean
• Mauricie–Centre-du-Québec
• Ontario

When metallizing is not the right answer

Metallizing is the wrong choice for a local touch-up, for new parts that can go into a zinc bath, or for a chemical environment that attacks zinc and aluminum.

• Touch-ups, field welds and small areas: cold galvanizing is often enough.
• New parts sized for a bath: shop hot-dip galvanizing may fit. Our article cold galvanizing vs hot-dip compares the options.
• Acid or alkaline environments, immersion in chemicals: an organic coating or lining fits better (protective coatings).

The site survey settles which option to use.

Typical Problems We Solve

• Paint systems that break down quickly at edges and scratches in salt-laden environments
• Parts too large or too heavy for hot-dip galvanizing, or that would distort in the bath
• Corrosion under insulation on carbon steel piping and vessels
• Structures in place that need metallic protection without being dismantled

What You Receive

• Technical quote stating the metal, process, preparation grade, target thickness and sealer or duplex system
• Steel blasted to SSPC-SP 5 or SP 10 and metallized to ISO 2063-2 and SSPC-CS 23.00
• Thickness readings, ASTM D4541 adhesion results and bend test records
• Job reference standard (JRS) and final inspection file

Timeline

Standards & Certifications

• ISO 2063-1 and ISO 2063-2: thermal spraying of zinc, aluminum and their alloys, design and execution
• SSPC-CS 23.00 / AWS C2.23 / NACE No. 12: application of thermal spray coatings (metallizing) of aluminum, zinc and their alloys on steel
• SSPC-SP 5 / NACE No. 1 and SSPC-SP 10 / NACE No. 2: white and near-white metal blast cleaning
• ASTM D4541: pull-off adhesion strength of coatings using portable testers

Industries We Serve

• Transportation and public infrastructure: bridges and civil structures
• Energy: transmission towers, poles, penstocks and plant structures
• Mining and metals: conveyors, structures and equipment in corrosive atmospheres
• Chemical and processing: insulated piping and vessels (TSA)

Service FAQ

Technical guides

• Zinc vs aluminum thermal spray
• Cold galvanizing vs hot-dip
• Thermal spray aluminum (TSA)
• Corrosion under insulation (CUI) guide
• ISO 12944 explained

Related applications

Concrete industrial use cases where this service is applied.