What we do · 02
Spraying
Two wires, one arc, and a coating built up layer by layer on a prepared substrate.
The Twin Wire Electric Arc 400 process
An arc spray head melts the alloy feed wires. DC electric current is carried by two electrically conductive, consumable 0.0625 in. diameter wires, fed to the spray gun from a dual drive wire feeder. An electric arc forms between the wire tips in the gap where the two are continuously directed.
A high velocity jet of nitrogen atomizes the molten metal as it forms, while the wires are melted by the arc. The atomizing gas accelerates the fine metal droplets away from the electrode tips to the prepared substrate. The molten particles impact the substrate to form a coating in a series of thin 3–5 mil overlapping layers, to the desired thickness.
How the work is run
- Inspection undertaken by Bureau Veritas — an impartial, internationally recognized third-party inspector
- Documented quality control and safety programs
- On-site computerized project management
- Confined-space entry on supplied breathing air, with a standby attendant
- Vessel handed back cooled, vented and inspected
- Weld overlay carried out where a customer requires it — with the shorter inspection cycle it brings stated up front
Wire
Twinalloy 625
Designed, milled and spooled to our strict specifications and made exclusively for Twin Wire Arc, Inc. Our thermal spray wire has proven to be impervious to the environments commonly found in digesters.
Tensile strength, cast and helix are controlled, enabling continuous feed over long distance — as required in digesters and in our stand-alone automated delivery system.
Our alloy is proven to be the most effective against corrosion, erosion and stress cracking in caustic mediums such as digesters.
Standards
ISO 9002 approved quality systems manufacture our wires. Our products meet or exceed the specification requirements of AWS, ASME, TUV, MIL and DIN standards.
| Alloy | Ni | Cr | Mo |
|---|---|---|---|
| Twinalloy 625 | 62.5 | 19–23 | 4–5 |
| 304 SS | 8–11 | 18–20 | — |
| 309 SS | 12–16 | 22–24 | 0.75 max |
| 316 SS | 11–14 | 16–18 | 2–3 max |