Full Encirclement Engineered Laminated Steel Sleeve System for Repairs and Augmentation of Pipelines: The Engineering Development, Validation Test Results, and Implications for Mitigation of Both Stress and Strain Dependent Integrity Threats

Abstract

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. An Engineering Critical Assessment (ECA) has been completed. This ECA follows the industry’s precedents of ASME B31G and ASME PCC-2 Article 4 type assessments 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 (96526.60 MP)a 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. The classic metal loss defect mitigation principle is reviewed and updated in light of these available technical advances. Finally, the implications for mitigation of both stress and strain dependent integrity concerns is discussed.