The Innovation of Steel Spring Technology: Full Encirclement Laminated Steel Sleeve Systems Engineered for Repairs and Augmentation of Pipelines
Proceedings Publication Date
Shawn Laughlin
Shawn Laughlin, Molly Laughlin Doran
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A full encirclement thin layer steel laminated sleeve system has been designed, developed, and optimized for pipeline integrity management applications. Development goals included the elimination of thixotropic concerns as well as the exclusion of the degradation of material properties of composite repairs. Elimination of cyclical fatigue of welded repairs and safety concerns associated with hot work were also considerations. The use of thin layer steel with a modulus matched to base pipe and steel’s homogenous isotropic properties enable axial calculations and evaluation of strain-based concerns. The thin layer steel laminated design results in extremely high fracture toughness and promotes intrinsic mitigation of potential future third party damage. The resulting system has demonstrated the reliable engineering data and analysis required for pipeline repairs and demonstrates applicability for the augmentation of existing pipes without defects.

Engineering Critical Assessment's (ECA's) have been completed. This ECA follows industry precedent in regards to assessment type and provides operators with greater functionality. This ECA has been named the Leewis Augmentation Analysis (LAA) and is presented, reviewed, and discussed.

Third party full scale ASME PCC-2 style burst testing has been completed. The results are presented. Highly instrumented tests were also conducted to determine an effective modulus of elasticity of the installed system as well as a determination of any delay in system acceptance of load. As installed, an effective modulus of 14 million psig (96526 MPa) with loading in layer 3 of the laminate at only 50 micro strain is reviewed. Long term creep and cyclical fatigue testing of the steel/adhesive laminate is presented and reviewed. 10 million cycles at 50% of ultimate lap shear has been achieved, which exceeds current industry practice by several orders of magnitude. Classic metal loss defect mitigation principles are reviewed and updated in light of these available technical advances.

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