Abstract: This invention relates to a method and apparatus for monitoring the amount of coating material that has been applied to a pipe. Opposed parallel sensing arms are positioned in contact with the coated pipe. One of the arms is movable relative to the other arm and in response to variations in the thickness of the coating. A direct mechanical linkage may be utilized to provide a readout of the variations in coating thickness or the movements of the arm may be used to vary the output of a potentiometer to provide an electrical readout. The potentiometer output may, in turn, be coupled with digital circuitry to provide a digital display. The circuitry may also include logic circuitry which will translate the variations in readings into positive or negative deviations from a desired predetermined coating thickness.

Abstract: A method for cutting an arcuate groove in an uncured concrete coating on an arcuate surface. A jet stream of water is directed at the coating along a line extending tangentially of the surface in a downward direction. The object is rotated at a relatively low speed in relation to the stationary water jet. The invention also encompasses a method of applying a concrete coating to pipe wherein after the cement is forced onto the pipe a wrapping material is wound around the pipe in a spiral pattern to hold on the concrete. The wrapping material may be a water impervious plastic which will affect curing of the cement without the aid of chemical curing agents.