Industries / Chemical processing
Chemical processing
Coatings for equipment operating in aggressive environments.
Thermal spray and cladding systems for equipment exposed to aggressive chemicals, high temperatures and abrasive flows. Selection considers fluid chemistry, operating conditions and mechanical loads.
Components and protection zones
Pump casings and impellers
Protection of wetted surfaces from corrosion, cavitation and slurry erosion.
- Zones:
- Volutes, casing walls, wear rings and blade surfaces.
- Coatings / bond coat:
- NiCrBSi; NiAl (bond coat, if required)
- Substrate:
- Cast iron, stainless and duplex steels.
Agitator shafts and mixer blades
Protection against corrosion, erosion and chemical attack.
- Zones:
- Shaft journals, seal zones, blades, edges and hub transitions.
- Coatings / bond coat:
- Co-Cr, Co-Cr-W; NiAl (bond coat, if required)
- Substrate:
- Stainless and duplex steels.
Valve seats and plugs
Maintaining sealing integrity in corrosive and abrasive service.
- Zones:
- Seat rings, plug outer surfaces and contact faces.
- Coatings / bond coat:
- Stellite 6 (Co-Cr-W); NiAl (bond coat, if required)
- Substrate:
- Stainless, duplex and alloy steels.
Reactor liners and baffles
Protection against corrosion and abrasive exposure.
- Zones:
- Vessel walls, baffle faces and edges, and nozzle penetrations.
- Coatings / bond coat:
- NiCrMo, NiCrBSi; NiAl (bond coat, if required)
- Substrate:
- Carbon steel and stainless-clad steel.
Heat-exchanger tubes and tube sheets
Protection against corrosion, deposits and thermal cycling.
- Zones:
- Tube bores, tube-sheet faces and holes, and headers.
- Coatings / bond coat:
- Cr3C2-NiCr; NiCr (bond coat, if required)
- Substrate:
- Carbon steel and 316 stainless steel.
Mechanical seal sleeves
Reduced fretting and wear; protection of contact surfaces.
- Zones:
- Working mating surfaces of seals.
- Coatings / bond coat:
- Engineered system selected for the service environment
- Substrate:
- Steels and alloys used in seal components.
Materials and applications
| System | Materials | Application |
|---|---|---|
| Nickel-based corrosion resistant | NiCrBSi, NiCrMo, Ni-Fe-Cr | Parts exposed to acids, alkalis and salt solutions; selection for the specific medium. |
| Cobalt-based corrosion resistant | Co-Cr-W (Stellite 6), CoCrMo | Parts combining wear, corrosion and high temperature. |
| Ceramic barrier | Al2O3, Cr2O3, ZrO2, TiO2 | Chemical and thermal protection of process surfaces. |
| Wear-resistant carbide | Cr3C2-NiCr, WC-CoCr | Slurries, abrasive flows and contact surfaces. |
| High-temperature | NiCrAlY, NiAl, CoNiCrAlY | Oxidation and hot-corrosion protection. |
Coating structure
- Functional layer
- Bond coat, if required
- Component material
Schematic, not to scale. Layer count and bonding mechanism depend on the selected material and process.
Coating processes
- HVOF
- Plasma spray (APS)
- HVAF
- Wire arc spray
- Cold spray (CS)
Typical applications, not a component specification. Composition, thickness, surface preparation and acceptance criteria must be selected for the operating conditions and validated by testing.