This Part 1 of European Standard EN 976 specifies the requirements and associated test methods for horizontal, cylindrical single wall tanks made of glass reinforced thermosetting resins (hereafter called tanks), and for their accessories, used for the underground non-pressure storage of liquid petroleum based fuels.The tanks specified by this European Standard are tanks with one or more compartments and with or without the possibility of leak detection.This European Standard covers two types of tanks, type A with manway, type B without manway and two classes of tank stiffness, class 1 and class 2. It also covers two grades of tanks, grade 1 for use with all petroleum based fuels and grade 2 limited to use with diesel fuels and heating oils.