ULC 669

This Standard provides minimum requirements for nonmetallic internal retrofit systems intended for field installation in underground tanks for the storage of flammable and combustible liquids, such as petroleum products, oxygenated fuel blends, oxygenates and other flammable and combustible liquids that can be demonstrated to be compatible with the internal retrofit system materials. These retrofit systems are nonmetallic thermoset (such as fibre reinforced plastic [FRP], epoxy, polyurethane [PUR] or polyesters) or thermoplastic (such as polyethylene [PE]) materials that may or may not be bonded to the interior tank wall of the host tank, depending upon the system type. These products typically use pre-fabricated sections with coatings applied on site, or homogeneous or layered spray-on / roll-on materials applied on site, and may optionally cover minor repair prior to the installation of a retrofit system, and the installation of bulkheads to the host tank. The three types of internal retrofit system are:

A. Lining systems, which provide only primary containment of stored fuels, and do not add significant structural strength to the host tank;
B. Upgrade systems, which provide both primary containment and secondary containment of stored fuels with interstitial monitoring, and are co-structural with the host tank; and
C. Structural systems, which provide both primary containment and secondary containment of stored fuels with interstitial monitoring. This system may provide a primary containment of stored fuels and utilizes the host tank as secondary containment of stored fuels with interstitial monitoring, or the system may provide both primary containment and secondary containment of stored fuels with interstitial monitoring independent of the host tank.