CAN/ULC-S601 vs. S602 — which tank certification applies to yard diesel vs. fuel oil
Confidence: Verified against CAN/ULC standard scopes and Ontario Fire Code Part 4.
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
| Standard | Scope | Typical use |
|---|---|---|
| CAN/ULC-S601 | Shop-fabricated steel aboveground tanks for flammable and combustible liquids — single- and double-wall horizontal cylindrical tanks for diesel and gasoline | Yard tanks for on-road clear-diesel fleet refuelling; cardlock dispensers; commercial bulk diesel |
| CAN/ULC-S602 | Aboveground steel tanks for fuel oil and lubricating oil — maximum capacity 2,500 L, single-wall and secondary-containment | Generator base tanks; basement heating-oil tanks; lubricating oil day tanks |
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
op-on-farm-bulk-diesel-storage-compliance.
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 reg-oreg-217-01-liquid-fuels and reg-oreg-216-01-petroleum-mechanics.
On marketing pages
This distinction is the most-confused item in customer conversations about yard tanks. Marketing-page copy on tank installation should lead with the operator's situation ("a yard tank to fuel your trucks") and let the standard live in the source footer. Quoting an S602 tank for a clear-diesel application — or letting a customer buy one online expecting B&J to hook it up — produces a non-compliant install.
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
- source.confidence: verified
- concept_category: tank certification / regulatory distinction
- applies_to_services: tank installation, tank inspection, on-site refuelling, on-farm bulk diesel storage
- applies_to_audiences: anyone specifying or quoting a yard tank; copywriters editing tank-services and on-site-refuelling pages