Overview
Induscoat applies coatings to penstocks, turbines and hydraulic structures at hydroelectric plants in Quebec and Ontario, working from LaSalle, Montreal. Immersed interiors, atmospheric exteriors, cavitation and erosion repair: surface preparation, ISO 12944 Im1 systems and recorded inspections, carried out during the unit outage planned with the operator.
Induscoat coats and repairs the steel structures of hydroelectric plants in Quebec and Ontario, working from LaSalle, Montreal: penstock interiors in immersion and exteriors in atmosphere, Francis and Kaplan turbines, spiral cases, draft tubes, gates, trash racks and stoplogs. Immersion systems are selected under ISO 12944 category Im1 (fresh water) and AWWA C210 for water pipe interiors. Erosion and cavitation damage is rebuilt with filled epoxy and protected with anti-cavitation coatings. Surfaces are prepared to SSPC-SP 10 or SSPC-SP 5, or by hydro blasting, with dehumidification to keep the steel above the dew point in confined spaces. Work is carried out during planned unit outages, coordinated with the operator, with testing and specific measures for old lead or coal tar coatings.
The structures we treat
We treat the steel structures of a hydroelectric plant that are in contact with water or exposed to constant humidity. Each one faces a different mix of corrosion, sediment erosion and cavitation. This work is part of our industrial and protective coatings, our core business.
- Penstocks: interior in permanent immersion, exterior in humid atmosphere, in a gallery or in the open.
- Francis and Kaplan turbines: runners, blades, wicket gates, discharge rings and throat rings, where cavitation attacks.
- Spiral cases and stay rings: large immersed surfaces, accessible only during an outage.
- Draft tubes: cones and elbows, exposed to cavitation at the runner outlet and to erosion.
- Gates: fixed-wheel gates, radial gates, butterfly valves, guides and embedded parts.
- Trash racks and rakes: bars and frames, exposed to debris and abrasion.
- Stoplogs and bulkheads: elements stored in the air and lowered into the water for outages.
Work is carried out by our crews and qualified subcontractors, coordinated with the plant operator.
Systems and when to choose each
The system is chosen from the exposure of each zone. For fresh water immersion, ISO 12944 rates the exposure as category Im1, and ISO 12944-5 sets out matching systems (ISO 12944 explained). For steel water pipe interiors, AWWA C210 is the reference for liquid epoxy coatings.
- High-build immersion epoxy: interiors of penstocks, spiral cases and draft tubes. A barrier against water and oxygen.
- Ceramic-filled epoxy: areas eroded by sand and sediment, penstock intakes, trash racks.
- Elastomeric anti-cavitation coating: blades, discharge rings and draft tube cones. Its flexibility absorbs the impact of collapsing bubbles, where a rigid epoxy cracks.
- Metal-filled epoxy for rebuilding: filling cavitation pits and lost thickness before the finish coat (cold bonding repair).
- Atmospheric system (zinc, epoxy, polyurethane): penstock exteriors, gates above water, stoplogs in storage.
The thickness of each coat comes from the manufacturer's data sheet and is stated in the quote. Compatibility with the old coating is checked before any partial repair.
How the work runs during a unit outage
The work happens during the unit outage, whose date and length are set by the operator. Everything is therefore prepared before dewatering.
- Prior survey: inspection during an earlier outage or from photos, mapping of cavitation, erosion and corrosion areas.
- Work plan: system by zone, preparation method, dehumidification, access, schedule built into the outage schedule (project management).
- Dewatering and access: after lockout by the operator, set-up of scaffolding, lighting, ventilation and dehumidifiers.
- Preparation: abrasive blasting or hydro blasting, then profile and salt measurements.
- Repair and application: rebuilding of pits, stripe coat, full coats, anti-cavitation coating on target areas.
- Inspections and handover: thickness, holiday testing, full cure before rewatering, file handed to the operator.
Surface preparation and inspections
An immersion coating does not forgive incomplete preparation: the smallest patch of rust or salt under the film becomes a blister. The preparation grade and inspections are set in the quote.
- SSPC-SP 10 / NACE No. 2 (near-white blast cleaning): the usual minimum for immersion (NACE No. 2 surface preparation guide).
- SSPC-SP 5 / NACE No. 1 (white metal): when the system or service calls for it, notably under anti-cavitation coatings.
- Hydro blasting to the specified WJ grade: to remove salts and thick old coatings in confined spaces.
- ISO 8502-4: assessment of the condensation risk before each coat, from relative humidity, dew point and steel temperature.
- SSPC-PA 2: dry film thickness measurement.
- Holiday testing: detection of film discontinuities before rewatering (holiday test).
For independent coating inspection, see our coating inspection service.
Site conditions and safety
A power plant sets its own constraints: confined spaces, cold water, humidity and a tight schedule. They are settled with the operator before the outage.
- Humidity: penstock steel stays cold and the air inside is saturated. Dehumidification and air heating keep the steel above the dew point during preparation and cure.
- Confined spaces: entry permit, ventilation, gas detection, continuous attendant and a rescue plan suited to long penstocks and shafts.
- Lockout: hydraulic and electrical isolation done by the operator, verified before each entry.
- Coordination: work alongside the mechanical and electrical crews of the outage, in a single schedule.
- Old coatings: older structures often carry lead-based paint or coal tar coatings. Removing them calls for testing and specific measures (lead paint removal).
- Waste: recovery of abrasive and blasting water so they do not reach the river.
- Winter: winter outages need a heated enclosure and a suitable product (cold-weather epoxy application).
Pricing: by quote
Hydroelectric structure coating is priced by quote. Six factors drive it:
- Area and geometry: straight penstock, spiral case, turbine blades.
- Condition: extent of cavitation, erosion and corrosion, volume of rebuilding.
- The old coating: thickness, lead, coal tar.
- The system and preparation grade.
- Access and dehumidification in confined spaces.
- The length of the outage and the round-the-clock work it may require.
Send photos, structure dimensions, planned outage dates and the location with your quote request: we reply within 24 business hours.
Where we work
Induscoat works at hydroelectric plants across Quebec and in Ontario, 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 a coating is not enough
A coating is not enough when cavitation has cut deep into the base metal or when the hydraulic cause is not addressed. An anti-cavitation coating slows the attack; it does not correct operation away from the best efficiency point or a blade profile defect.
Major metal loss on a runner calls for weld overlay by a specialist, before any coating. A thinned or cracked penstock first needs an integrity assessment. For localized rebuilding repairs and equipment refurbishment, see our maintenance and rehabilitation service. To understand the source of recurring damage, our strategic advisory service analyzes the cause before the system is chosen.
Typical Applications
- Penstock lining and penstock exterior coating
- Turbine coating and cavitation repair on Francis and Kaplan runners, discharge rings and draft tubes
- Spiral case and stay ring coating during unit outages
- Coating of gates, trash racks, stoplogs and embedded parts
Typical Problems We Solve
- Cavitation pitting on turbine blades, discharge rings and draft tube cones
- Sediment erosion and corrosion inside penstocks and spiral cases
- Condensation on cold steel in confined spaces that prevents coating
- Old lead-based or coal tar coatings on older structures
What You Receive
- Work plan by zone stating the system, preparation grade, dehumidification and outage schedule
- Cavitation and erosion areas rebuilt and protected before rewatering
- Condition records per ISO 8502-4, dry film thickness per SSPC-PA 2 and holiday test results
- Close-out file for the operator with data sheets, batch numbers, photos and a map of treated areas
Timeline
Set in the quote according to the outage dates and length set by the operator, surface area, extent of damage and access. Quote sent within 24 business hours of receiving photos and dimensions.
Standards & Certifications
- ISO 12944-2 and ISO 12944-5: immersion category Im1 (fresh water) and protective systems
- SSPC-SP 10 / NACE No. 2 and SSPC-SP 5 / NACE No. 1: near-white and white metal blast cleaning
- AWWA C210: liquid epoxy coatings for the interior and exterior of steel water pipe
- ISO 8502-4: assessment of the probability of condensation before coating
Industries We Serve
- Hydroelectric generation: plants, penstocks and turbines
- Dams and water control structures: gates, stoplogs, trash racks
- Industrial self-generation: plant-owned hydro stations
- Water intakes and pumping stations: intake structures and large pipes
Service FAQ
Which coating is used inside a penstock?
Usually a high-build immersion epoxy, selected for ISO 12944 category Im1 (fresh water), with AWWA C210 as the reference for steel water pipe. Where sediment erodes the surface, a ceramic-filled epoxy is used in the affected areas. The steel is prepared to SSPC-SP 10 at a minimum, and the system is checked for compatibility with any coating that remains.
Can a coating repair cavitation damage on a turbine?
It can rebuild shallow and moderate pitting with filled epoxy and slow further attack with an elastomeric anti-cavitation coating. It does not fix the hydraulic cause, and deep metal loss on a runner calls for weld overlay by a specialist first. The survey maps which areas suit a coating repair and which do not.
How do you deal with humidity inside a penstock?
With dehumidifiers and air heating installed after dewatering, so the steel stays above the dew point during preparation and cure. The condensation risk is assessed under ISO 8502-4 before each coat, and readings are recorded. Without that control, blasted steel flash-rusts and the coating does not bond.
How do you fit the work into a unit outage?
The outage dates and length are set by the operator. We survey beforehand, plan by zone, and build our schedule into the outage schedule with the mechanical and electrical crews. Access, dehumidification and materials are ready on day one, and full cure is planned before rewatering.
How much does penstock or turbine coating cost?
Pricing is by quote. It depends on area and geometry, the extent of cavitation, erosion and corrosion, the old coating, the system, access and dehumidification, and the length of the outage. Send photos, dimensions, planned outage dates and the location: we send a quote within 24 business hours.
Technical guides
Related applications
Concrete industrial use cases where this service is applied.
Other Services
Areas we serve
- Industrial coatings and maintenance in Quebec
- Industrial coatings and maintenance in Montreal
- Industrial coatings and maintenance in Ontario
- Industrial coatings and maintenance in Abitibi-Témiscamingue
- Industrial coatings and maintenance on the Côte-Nord
- Industrial coatings and maintenance in Saguenay–Lac-Saint-Jean
- Industrial coatings and maintenance in Mauricie and Centre-du-Québec
- Industrial coatings and maintenance in Montérégie