Hydro Blasting & High-Pressure Water Jetting

What we treat with water

Hydro blasting replaces abrasive when dust, salts or the thickness of the existing coating make blasting a poor fit. Pressurized water strips paint, rust and deposits without throwing grit, and it dissolves the salts that abrasive leaves at the bottom of pits. Water blasting is mainly used to prepare a substrate for our industrial and protective coatings, our core business.

• Tanks and water towers: removal of old interior or exterior coatings, salt washing before repainting.
• Penstocks and hydraulic structures: interior stripping in confined spaces, where abrasive dust is hard to extract.
• Heat exchangers and process equipment: industrial high-pressure cleaning of tube bundles, water boxes and hard deposits.
• Concrete: removal of laitance, coatings and deteriorated concrete, up to hydrodemolition before repair (concrete protection).
• Steel structures in operating plants: areas where abrasive dust would threaten motors, bearings or product.

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

Pressure levels and when to choose each

The pressure level is chosen from what has to come off. The joint SSPC-SP WJ / NACE WJ standards define four categories: low-pressure water cleaning, high-pressure water cleaning, high-pressure waterjetting and ultra-high-pressure waterjetting. The thresholds for each category are those in the standard; the quote states the category used.

• Low pressure: washing off salts, dust, light oils and chalking between coats or before maintenance repainting.
• High-pressure cleaning: removal of loose rust, flaking paint and soft deposits.
• High-pressure waterjetting: removal of adherent paint and hard deposits on steel and concrete.
• Ultra-high-pressure waterjetting: removal of thick, well-bonded coatings, residual scale in pits, and stripping to bare metal.

Water does not create a surface profile: it exposes the profile already under the old coating (surface profile). On new steel, or when the new system needs a profile the substrate no longer has, abrasive blasting is still required, alone or combined with water washing.

WJ cleanliness grades and flash rust

The visual cleanliness grade is specified with SSPC-SP WJ-1 to WJ-4 / NACE WJ-1 to WJ-4, which replace the former SSPC-SP 12 / NACE No. 5. The lower the number, the cleaner the surface.

• WJ-1: clean to bare substrate, for immersion systems and severe environments.
• WJ-2: very thorough cleaning; only residual staining remains.
• WJ-3: thorough cleaning; a larger share of staining is allowed.
• WJ-4: light cleaning; removal of loose material only.

The same standards set a non-visible contamination level (NV), meaning residual soluble salts, measured on site. They also set the flash rust grade allowed at the time of coating.

Wet steel rusts within hours. This flash rust is rated light, medium or heavy (L, M, H) under ISO 8501-4, which also defines the Wa 1, Wa 2 and Wa 2½ preparation grades. The grade allowed depends on the coating: some products tolerate light flash rust, others do not. A flash rust inhibitor can be added to the water, but only if the coating manufacturer accepts it, because its residue can affect adhesion.

How a hydro blasting job runs

A hydro blasting job follows six steps, from the survey to the file handed over before coating.

• Survey: substrate, thickness and type of existing coating, possible lead, access, water supply and drainage points.
• Technical quote: pressure category, target WJ grade, NV level, allowed flash rust grade, water and waste handling.
• Site preparation: marked exclusion zone, equipment protection, tarps and water recovery.
• Stripping: successive passes to the target grade, with rework of difficult areas (welds, edges, pits).
• Inspections: visual check against the WJ grade, soluble salt measurement, flash rust rating just before priming.
• Handover: surface accepted in writing, then coating applied within the time the day's conditions allow.

Inspections, standards and water handling

Each inspection ties to a standard and is recorded in the file.

• SSPC-SP WJ-1 to WJ-4 / NACE WJ-1 to WJ-4: visual cleanliness grade and non-visible contamination level.
• ISO 8501-4: preparation and flash rust grades after water jetting.
• ISO 8502-6 and ISO 8502-9: sampling and measurement of soluble salts on the surface.
• Manufacturer's data sheet: flash rust grade and salt level the coating accepts.

Blasting water is not clean water: it carries paint chips, rust and, on older structures, sometimes lead. It is recovered, settled or filtered, then discharged or disposed of under site and municipal rules. Solid waste is characterized before disposal. If the old paint contains lead, the job follows the measures of our lead paint removal service.

Site conditions and safety

High-pressure water cuts flesh as easily as paint: safety is planned before the first pass. We follow the waterjetting industry's recommended practices (WJTA-IMCA) and the occupational health and safety rules of each province.

• Exclusion zone: marked perimeter around the operator, closed to anyone else while jetting.
• Protective equipment: face shield, hearing protection, jet-resistant clothing and boots, gloves.
• Tool control: dead-man trigger gun, hoses and fittings checked every shift.
• Confined spaces: entry permit, ventilation, continuous attendant and rescue plan, inside tanks and penstocks.
• Winter: water freezes on steel and in hoses. Outdoor work needs a heated enclosure, or waits for warmer weather.
• Operating plant: electrical equipment protected from splash and water mist.

Pricing: by quote

Hydro blasting is priced by quote, because the cost depends on the substrate and on what has to come off. Six factors drive it:

• Area and shape of the parts: a flat wall goes faster than an exchanger bundle or a lattice frame.
• The existing coating: thickness, adhesion, presence of lead.
• The target WJ grade and salt level.
• The pressure category and the equipment it calls for.
• Access: at grade, at height, in a confined space.
• Water and waste handling, and the work window (shutdown, winter).

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

Where we work

Induscoat provides hydro blasting 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 water is not the right answer

Hydro blasting is the wrong choice when the specified coating needs a surface profile the substrate does not have, on new steel for instance. Nor is it right when the water can be neither recovered nor drained, or when cold weather prevents keeping the surface dry until priming.

In those cases, abrasive blasting creates the profile and leaves a dry surface. A combined approach is common: water washing to remove salts, then blasting for the profile. For fragile parts or equipment that tolerates neither water nor abrasive, glass bead and dry ice blasting may fit. The survey settles which option to use.

Typical Problems We Solve

• Soluble salts left in pits that cause blistering under a new coating
• Thick, well-bonded old coatings that abrasive removes slowly
• Abrasive dust not acceptable near motors, bearings, product or in confined spaces
• Flash rust on wet steel that must stay within the grade the coating accepts

What You Receive

• Technical quote stating the pressure category, WJ grade, NV level and allowed flash rust grade
• Surface stripped to the specified SSPC-SP WJ / NACE WJ grade
• Soluble salt readings and ISO 8501-4 flash rust rating recorded before coating
• Record of water and waste recovery and disposal

Timeline

Standards & Certifications

• SSPC-SP WJ-1 to WJ-4 / NACE WJ-1 to WJ-4: waterjet cleaning of metals
• ISO 8501-4: preparation grades and flash rust grades after high-pressure water jetting
• ISO 8502-6 and ISO 8502-9: sampling and measurement of soluble salts
• WJTA-IMCA: recommended practices for the use of high-pressure waterjetting equipment

Industries We Serve

• Energy: penstocks, gates, tanks and heat exchangers
• Mining: process tanks, thickeners and concrete structures
• Water and wastewater: tanks, water towers, concrete basins
• Chemical and processing: heat exchangers, tanks and equipment in operating plants

Service FAQ

Technical guides

• NACE No. 2 / SSPC-SP 10 surface preparation
• Surface profile: definition and measurement
• Industrial tank lining selection
• Coating failure modes and diagnosis

Related applications

Concrete industrial use cases where this service is applied.