Internal Pipe Inspection

The television inspection of a sewer line section. A CC-TV camera is moved through the line at a slow rate and a continuous picture is transmitted to an above ground monitor; see also Physical Pipe InspectionThe crawling or walking through manually accessible pipe lines. The logs for physical pipe inspection record information of the kind detailed under TELEVISION INSPECTION. Manual inspection is only undertaken when field conditions permit this to be done safely. Precautions are necessary..

Inversion

The process of turning a fabric tube inside out with water or air pressure as is done at installation of a cured in place pipe.

Invert

The lowest point of the pipe, tunnel, or shaft.

Invert Level (Elevation)

The level (elevation) of the lowest portion of a liquid-carrying conduit, such as a sewer, which determines the hydraulic gradient available for moving the contained liquid.

Ion

An electrically charged atom (Na+, Al+3, CL-, S-2) or group of atoms known as “radicals” (NH4+, SO4-2, PO4 3).