4.3.1.1. This Section applies to storage tanks for flammable
liquids and combustible liquids. Atmospheric storage tanks 4.3.1.2. (1) Subject to Sentences (2), (3), (4), (5), (6), (7) and (8) and Section 4.9, atmospheric storage tanks shall be built in accordance with (a)  API 12B, “Bolted Tanks for Storage of Production Liquids”, (b)  API 12D, “Field Welded Tanks for Storage of Production Liquids”, (c)  API 12F, “Shop Welded Tanks for Storage of Production Liquids”, (d)  API 650, “Welded Tanks for Oil Storage”, (e)  CAN/ULC-S601, “Standard for Shop Fabricated Steel Aboveground Tanks for Flammable and Combustible Liquids”, (f)  CAN/ULC-S602, “Aboveground Steel Tanks for Fuel Oil and Lubricating Oil”, (g)  ULC-S603, “Standard for Steel Underground Tanks for Flammable and Combustible Liquids”, (h)  CAN/ULC-S603.1, “External Corrosion Protection Systems for Steel Underground Tanks for Flammable and Combustible Liquids”, (i)  ULC-S615, “Standard for Reinforced Plastic Underground Tanks for Flammable and Combustible Liquids”, (j)  CAN/ULC-S652, “Standard for Tank Assemblies for the Collection, Storage and Removal of Used Oil”, (k)  CAN/ULC-S653, “Standard for Aboveground Steel Contained Tank Assemblies for Flammable and Combustible Liquids”, (l)  ULC-S655, “Aboveground Protected Tank Assemblies for Flammable and Combustible Liquids”, or (m)  ULC/ORD-C142.5, “Concrete Encased Steel Aboveground Tank Assemblies for Flammable and Combustible Liquids”. (2) Tanks built in conformance with Clauses (1)(a), (b) and (c) shall be used only for the storage of crude petroleum at oil fields. (3) When necessitated by possible contamination of the liquid to be stored or possible rapid corrosion of the tank, storage tanks need not conform to Sentence (1), provided that they are designed and built in conformance with good engineering practice for the material being used. (4) Atmospheric storage tanks shall not be used for the storage of flammable
liquids or combustible liquids
at temperatures at or above their boiling points. (5) Existing in-service aboveground atmospheric storage tanks that do not comply with Sentence (1) may remain in-service if the tanks (a)  are not leaking, (b)  have no dents greater than 30 degrees or 35 mm in depth from the normal configuration, (c)  have no pitting in excess of 3 mm, and (d)  have metal thickness of at least 50% of the minimum permissible thickness specified in an applicable standard referred to in Sentence (1). (6) Existing aboveground atmospheric storage tanks that do not comply with Sentence (1), (3), (5) or (9) shall be refurbished in conformance with Article 4.3.1.10. or be replaced. (7) Existing in-service underground storage tanks that do not comply with Sentence (1) may remain in-service if the tanks are not leaking and steel storage tanks and associated piping are protected from external corrosion in accordance with Subsection 4.3.9. (8) Existing underground storage tanks that do not comply with Sentence (1), (3) or (7) shall be refurbished in conformance with Article 4.3.1.10. or be replaced. (9) Existing aboveground atmospheric storage tanks that comply with ULC/ORD-C142.16-1994, “Protected Aboveground Tank Assemblies for Flammable and Combustible Liquids”, are deemed to comply with Clause (1)(l). (10) In-service atmospheric storage tanks that were installed on or before December 31, 2014 and that do not comply with Sentence (1) may remain in-service if they do not leak and if the tanks met the requirements of this Code on December 31, 2014, as it read on that day. Low pressure storage tanks and pressure vessels