OSHA doesn’t have legal authority in Canada but it’s prudent to keep an eye on their regulations. Since 2018 ladder cages cannot be used without personal fall arrest equipment or a ladder safety system on heights 24′ or higher. That height would apply to ladders on API 750 bbl tanks and ULC tanks greater than 70,000 litres. The Alberta occupational safety code has not yet adopted this change. See the OSHA guide here.