Standard for Steel Underground Tanks for Flammable and Combustible Liquids

1.1 Except as described in Clause 1.7, these minimum requirements cover single and double wall cylindrical steel, non-pressure tanks of the horizontal type that are used for the underground storage of flammable liquids and combustible liquids, that are compatible with the material of construction.

In addition to this Standard's traditional safety requirements for underground steel tanks that primarily evaluate structural integrity and mitigate environmental hazards from loss of liquid containment under expected normal conditions; optional construction and/or performance requirements, and associated ratings, intended to address more severe conditions associated with Climate Change are included in Appendix f.

1.2 These minimum requirements cover double wall tanks with provision for leak detection monitoring of the interstice between the walls.

NOTE: The designs identified in this Standard are satisfactory for vacuum and/or electronic monitoring devices. (Refer to Figure 1.)

1.3 This Standard also provides design criteria for integral connections (connection rings/collars) for spill containment sumps or manway risers.

1.4 These minimum requirements cover tanks, which are fabricated, inspected and tested for leakage before shipment from the factory as completely assembled vessels.

NOTE: For the requirements for tanks provided with corrosion protection systems at the factory, refer to the Standard CAN/ULC-S603.1, Standard for External Corrosion Protection Systems for Steel Underground Tanks for Flammable and Combustible Liquids.

1.5 These minimum requirements cover tanks up to a maximum capacity of 250 000 L.

1.6 The requirements in this Standard are for the construction of stationary tanks and do not cover their installation, maintenance and operation. The installation, maintenance and operation of these tanks may be covered by any of, but not limited to, the following documents:

A    National Fire Code of Canada, Part 4;

B    CSA B139,  Installation Code for Oil Burning Equipment;

C    API RP 1615,  Installation of Underground Petroleum Storage Systems;

D    CCME PN 1326,  Environmental Code of Practice for Aboveground and Underground Storage Tank Systems Containing Petroleum and Allied Petroleum Products;

E    NFPA 30,  Flammable and Combustible Liquids Code; and

F    Regulations of the appropriate authority having jurisdiction.

1.7 Where described elsewhere in the Standard, an alternative means of demonstrating compliance is provided in Subsection 8.3, Alternative Compliance Path. Tank designs subjected to the alternative compliance path need not be cylindrical. It is intended that proponents will use one of the design-based approaches identified in the rest of the Standard, or that described in Subsection 8.3, Alternative Compliance Path, as an equivalent means of obtaining certifications for their products.

1.8 The requirements in this Standard cover products that are integral or built-in to the tank.

NOTE: These requirements do not cover products not integral to the tank, such as spill containment sumps.

1.9 Except for optional Climate Change Adaptation requirements in Appendix f, these requirements do not cover special evaluations for resistance to, or use after, earthquakes, floods, high wind events, or other natural disasters.

NOTE: See the Note at the beginning of Appendix f for further information on the terms “Adaptation” and “Mitigation”, as they pertain to Climate Change.