Crack Arrestor

Clock Spring®" refers to a family of related fiber glass-and-resin matrix products developed by NCF Industries Inc. under a contract with the Gas Research Institute (GRI). It is used to repair blunt defects in pipes or arrest ductile fractures in high-pressure gas pipelines. The system operates by transferring the hoop stress from the defect, through high compressive strength filler material to the composite sleeve (Clock Spring®) wrapped around, and bonded to the pipe. As a crack arrestor, the composite absorbs the energy of the fracture arresting the crack. The composite is e-glass and polyester resin. All the e-glass fibers are continuous strands aligned in the hoop direction providing a tensile strength of 80,000 psi. The resin in the composite protects the glass strands and provides the shape memory that aids in installation. There is no need for welding or cutting the pipeline, increasing safety and eliminating environmental risk and release of greenhouse gases.