With the increasing use of directional drilling and micro tunnelling techniques for road, rail and other underground pipeline right of way crossing applications the Clock Spring fully bonded composite system is increasingly being used for casing spacer applications to prevent damage and wear to the main pipeline and coating when installed (pushed/pulled) into the casing and to centralise the pipe once in the casing.
Traditional casing spacers tend to provide a segmented tooth profile and as such point loading and contact to the carrier pipe. This often results in the spacer being broken or coming loose during the pipe installation process (Fig 1).
Derived from the highly successful transmission pipeline corrosion repair system, the Clock Spring casing spacer features the same full cured 8 layer high strength composite laminate coil which is wound onto the pipe and bonded in place using a high lap shear strength adhesive. Once installed the coil typically provides a 1⁄2“ (12.5mm) stand off spacing distance from the pipe circumference, however additional layers can be applied if a greater stand off distance is required. Figs 2 and 3 show the coil applied to the pipe and installed either side of a girth weld joint.
The coil surface is smooth and provides a low coefficient of friction between the composite surface and carrier pipe (Fig 4). Fig 5 shows the coil after the pipe installation in this instance on a 8” pipe after a 700’ (210m) pull through.
The Clock Spring system is available to suit pipe diameters as standard from 4” to 56” with coil widths being available of up to 12”.
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