SBIR-STTR Award

A nondestructive tool will be developed to quatitatively assess residual stress in pipelines from the exterior and through coatings. Residual stress is a critical factor that determines the cracking susceptibility of pipeline steels, but existing methods for measuring mechanical damage in pipeline steels are incapable of quantifying the residual stress levels. A larger gouge or dent does not necessarily signify worse damage that a smaller gouge or dent; it is more important to focus on the actual residual stress levels induced by damage. Knowledge of the residual stress levels provides an accurate means to assess the severity of the damage and improve the pipeline integrity, ultimately reducing the amount of unneccessary removal and repair applications. The unique use of low frequency impendance sensors will allow for through thickness pipeline integrity assessment. Phase I will low-frequency impendance analysis to perform in-situ residual stress measurements on simulated mechanically damaged pipeline steel to compare with finite element and other stress estimation techniques. Phase II and Phase III efforts will develop a calibrated portable low frequency impedance toll for in-situ assessment of pipeline damage without removal of coatings.

There exists a wide-range need in both industry and government for quantitative residual stress measurements. Generation 2 Materials Technology LLC (G2MT) will collaborate with partners from industry and government to calibrate and commercialize the eStress system to assess residual stress from mechanical damage and re-rounding. The industrial members, consortiums, and government laboratories who have agreed to provide support and/or cost-share for this Phase II initiative represent a wide range of potential users: Stress Engineering Services, Structural Integrity Associates, Lloyds Energy Americas, ASME International, Pipeline Research Council International, TMR Exploration, Shell, Conoco-Phillips, British Petroleum, the Canadian Neutron Beam Centre, and the National Aeronautics and Space Administration. The Phase II technical objectives include: Objective 1. Begin calibrations to develop eStress™ system to quantify residual stress on all common grades of pipeline steel, which can have yield strengths from 40 ksi (past)to 120 ksi (future). Objective 2. Calibrate eStress™ system to quantify the residual stress measurements. Objective 3. Calibrate eStress™ system for all other variables associated with steel pipelines to increase accuracy of eStress™ system. Objective 4: Calibrate eStress™ system for lift-off variations due to coatings, corrosion product, user handling of sensors, etc. Objective 5: Complete the packaging of the eStress™ system for the field. Objective 6: Determination of optimum data form for integrity management program. Objective 7: Develop training procedures and manuals to use the eStress™ system. Objective 8: Develop new codes and standards for acceptable residual stress levels for mechanical damage. Objective 9: Deploy the eStress™ system in the field.