Cement Mortar Lining
Cement Mortar Lining (CML) is the application of a cement mortar (typically about 4 mm thick) to the inside of pipelines to protect against corrosion. Typically cement mortar lining is applied using a remotely controlled spray head, although it can be hand sprayed in man-entry sizes and over smaller areas/lengths of pipe. Mechanically sprayed application allows for faster coverage so less time on site. In man-entry size pipes first the pipe must be effectively cleaned to prepare the surface for the application of the mortar. Usually if hand-sprayed, guide pins may be used to ensure that the operator sprays the mortar to the required depth. In non-man-entry pipes, remotely controlled systems are utilised once the pipe has been cleaned and prepared. Depth of coating in these cases is established by calculating the mortar flowrate and speed of movement through the pipe of the spray head to provide the required thickness of application. In both man-entry and non-man-entry sized pipes the effective length that can be lined will depend on the availability of pumping systems that can present the lining material to the spray head over the distance required.
Practically, in pipes that are utility based, lining is completed on a manhole-to-manhole distance and this limits the lengths that are lined in one run. It should be noted that in recent years the use of cement mortar as the lining material of choice has waned as resin based sprays have become more widely available.