1.1 This specification covers concrete drain tile with internal diameters from 100 to 900 mm, that are intended to be used for surface and subsurface drainage. 1.2 This specification is the metric counterpart of Specifica This specification covers concrete drain tile, to be used for surface and subsurface drainage. Manufactured drain tile shall be of the following classes: standard-quality concrete drain tile, extra-quality concrete drain tile, heavy-duty extra-quality