1.2 Verifying Material Compatibility
As the Class B operator you must ensure that components and equipment that comprise the UST system for which you are responsible have the proper listing and labeling certifying they are compatible with the product to be stored in the UST.
Components must have proof of approval by an independent third- party testing organization such as Underwriter's Laboratories (UL®).
Proof of compatibility is usually a certificate or label that is attached to a component. The label contains information about a testing standard that the component was tested against for the product application by the testing organization.