Circumferential

Around the inner surface of a circular pipe cross section.

Circumferential Coefficient of Expansion and Contraction

The fractional change in circumference of a material for a unit change in temperature.

Cleaning

An action of a boring machine to remove spoil that occurs when the auger is rotating while axially stationary.

Close-fit

Description of a lining system in which the new pipe makes close contact with the defective pipe at normal or minimum diameter. An annulus may occur in sections where the diameter of the defective pipe is in excess of this.

Closed Face

Term referring to one mode of operation of a traditional tunnel boring machine (TBMSee Tunnel Boring Machine.).