The single most-confused yard-tank question: which ULC standard does my tank need to be built to? The answer depends on the service, not the appearance of the tank.

The two standards

Related: CAN/ULC-S603 is the underground tank standard; ULC-S655 / S653 / S652 cover protected, contained, and used-oil tank assemblies.

The practical rule

• Yard tank for refuelling licensed motor vehicles (on-road clear diesel) → S601. Governed by O. Reg. 217/01 (Liquid Fuels) and the LFHC. Even if a customer's old fuel-oil tank is sitting unused in the yard, it should not be repurposed for clear-diesel motor-vehicle refuelling — it was certified to S602, not S601.
• Heating-oil tank for a furnace, or a generator day tank → S602. Governed by O. Reg. 213/01 (Fuel Oil) and CSA B139.
• On-farm diesel for off-road equipment (tractors, combines) → S601 still applies because it's a flammable/combustible-liquids tank, not a fuel-oil heating tank. See On-farm bulk diesel storage — Ontario compliance (Fire Code, LFHC, TSSA, OFA).

The Ontario Fire Code, Part 4, Section 4.3.1.2(1) lists the acceptable aboveground-tank standards: API SPEC 12B/12D/12F, API STD 650, CAN/ULC-S601, S602, S603, S603.1, S615, S652, S653, S655, ULC/ORD-C142.20. Selection from this list is driven by service, not by tank shape.

Installation

Any aboveground installation under O. Reg. 217/01 requires a TSSA-certified Petroleum Mechanic holding a PM.3 certificate (O. Reg. 216/01). See (unpublished reference) and Regulation: O. Reg. 216/01 (Petroleum Equipment Mechanics).

Sources & structured attribution

• source.document: CAN/ULC-S601 Shop Fabricated Steel Aboveground Tanks for Flammable and Combustible Liquids (ulc.ca); CAN/ULC-S602 Aboveground Steel Tanks for Fuel Oil and Lubricating Oil (ulc.ca); Ontario Fire Code O. Reg. 213/07, Part 4, Section 4.3.1.2
• source.captured_date: 2026-05-16
• concept_category: tank certification / regulatory distinction