What drives the duration is not the application
On an internal lining job, application is the shortest step. Blasting, waiting for ambient conditions and curing are what drive the schedule. A plan built on "two coats, two days" meets that reality on day three, when the tank is still not blasted because the extraction was undersized.
The real sequence runs through seven stages, only one of which involves applying product.
| Stage | What governs it |
|---|---|
| Emptying, cleaning, gas-freeing | Nature of the stored product, confined-space entry procedure |
| Wall inspection | Actual substrate condition — this is where surprises appear |
| Blasting to the required grade | Abrasive throughput, extraction, access; the longest stage |
| Cleanliness, profile and salt testing | Measurements on the wall, before any application |
| Coat application | The shortest, if ambient conditions allow |
| Cure | Set by the product and the temperature, not compressible |
| Final inspection and return to service | Thickness, continuity, documentation |
Blasting: the stage that blows up
The cleanliness grade required for immersion service is high — typically near-white metal, designated SSPC-SP 10 / NACE No. 2 under the American reference or Sa 2½ under ISO 8501. Our surface preparation guide covers what that means on the wall, and ISO 8501 versus SSPC explains which of the two systems should govern your acceptance.
Three factors make this stage drift:
- Access. A single manway limits abrasive throughput, spent-media removal and operator count. It is often the dominant constraint, and it gets discovered too late.
- Actual wall condition. Deep pitting does not blast like sound steel: pits retain contaminants and salts, and demand specific treatment.
- Soluble salts. Invisible, they survive blasting and cause osmotic blistering months after return to service. Testing them and, if needed, washing followed by re-blasting, adds to the schedule.
Dew point: the constraint that is not negotiable
A coating is not applied to a wall whose temperature sits too close to the dew point: invisible condensation destroys adhesion. The usual rule keeps the substrate temperature above the dew point with a margin, with ambient conditions recorded at intervals throughout application.
In Quebec and Ontario, this constraint decides feasibility. A November-to-January shutdown on an unheated tank almost always requires heating and dehumidification — a cost and schedule item in its own right, and leaving it out of the quotation is the most frequent cause of overrun. A spring window is kinder but concentrates demand: qualified contractors are booked months ahead.
Cure time does not compress
This is where schedule pressure becomes dangerous. Cure time before return to service is set by the formulation and the temperature, and returning an under-cured lining to service produces softening, blistering or adhesion loss that will only appear later. No site organisation shortens that delay; only controlled elevated temperature does, within the manufacturer's stated limits.
It is also what links this job to the real service life of an immersion epoxy lining: most premature failures are decided during those few days.
Inspection: the difference between a job and a record
A documented job delivers, at minimum: cleanliness and profile records, soluble salt measurements, ambient condition logs during application, dry film thickness readings, and a holiday test — porosity detection, indispensable in immersion service. Product data sheets and batch numbers complete the file.
Without that record, the coating warranty is hard to enforce, and the next inspection starts from zero. On a storage tank governed by API 653, these records feed the inspection file directly — see our article on API 653 and composite tank repairs.
Five questions to ask before signing
- Which cleanliness grade, under which reference, and who pronounces acceptance? A quotation that says "careful blasting" commits to nothing.
- Are soluble salts measured, against what acceptance criterion?
- How will ambient conditions be maintained and recorded? Are heating and dehumidification included, or optional?
- What is the cure time before return to service, at the actual site temperature?
- What does the close-out file contain? Ask for the list of records, not a promise of quality.
FAQ
How long does it take to line a tank? It depends on area, access, substrate condition, the selected system and the temperature. Any duration quoted without those five inputs is a sales estimate. The useful sequence is: inspect first, then price the time stage by stage.
Can a tank be lined in winter in Quebec? Yes, with heating and dehumidification of the volume. It is not a technical impossibility but a cost and schedule item to build into the quotation from the start.
Must everything be blasted, or can we do localised repairs? Spot repairs are possible where the existing lining is broadly sound and compatible, after adhesion testing and evaluation. On a lining at end of life or of unknown type, partial repair postpones the problem by a few months.
What is a holiday test and why is it required? It is the detection of pinholes and through-film defects. In immersion service, a single holiday is enough to start under-film corrosion that will progress invisibly. It is performed after cure, before return to service.
Is lining always the right answer? No. If the wall has lost thickness beyond the calculated minimums, this is a fitness-for-service question, not a lining question. A lining protects sound steel; it does not restore lost thickness.
Scoping your next lining project
Induscoat prepares and lines storage tanks and process vessels across Quebec and Ontario, with the cleanliness, profile, salt and ambient records that make acceptance a formality rather than a debate. We price stage by stage — blasting, application, cure, inspection — so your shutdown window is held rather than hoped for. And if inspection shows the problem is wall thickness rather than lining, we will say so before you commit the budget. Tell us about the tank through our tank lining page or our quote request: reply within 24 business hours. Technical data sheets for the Induscoat range are published on the brand site, induscoat.com.
Hicham M, ing., PMP
Engineer and project manager (PMP) at Induscoat. Over 16 years of experience in industrial coatings, composite repairs and wear protection on mining, energy and petrochemical sites in Canada and internationally.