Abstract
Type A Compression Sleeves have been a technically viable repair method for corrosion, lamination-like features, and longitudinal crack-like features for the past 20+ years. A Type A Compression Sleeve relies on thermal expansion/contraction of the steel sleeve, which once the sleeve long seam welds are made, results in a compressive hoop stress in the carrier pipe at levels equal to or greater than generated at max operating pressure. This repair technology has been mostly marketed in Canada, and therefore, CSA Z662 includes the Type A Compression Sleeve in their list of approved permanent repair technologies. Over the past five years, there’s been an increased awareness in the United States as the technology has become referenced in industry documents such as the PRCI Pipeline Repair Manual and API 1176.
This paper provides an overview of a Type A Compression Sleeve, including the basis of how the repair system functions and how the sleeve is installed. Finally, this paper presents a series of full-scale tests and numerical modeling validating this innovative repair system. The use of induction heat, rather than open flame, provides a more consistent and traceable heat signature, allowing for confidence in the installed repair. Tests include synthetic cracks generated by precracking an EDM notch to generate a sharp-tipped crack, then heat tinted to provide a distinguishable boundary. The EDM notches, installed at a maximum of 50% of the wall thickness within the ERW seam, were subsequently repaired via the induction heating sleeve technology with and without flowing water in the carrier pipe. Test samples were cycled to 100,000 cycles, burst, and metallurgically examined. Post-test examination of the fracture surfaces revealed no discernable growth, therefore, indicating the technical viability of the repair technology as a permanent repair of crack-like features and provides an Operator another option when making repair decisions.
