Kamalu Koenig

REAL‐TIME LOW FREQUENCY IMPEDANCE MEASUREMENTS FOR DETERMINATION OF HYDROGEN CONTENT IN PIPELINE STEEL

The assessment of hydrogen content in pipeline steel is an essential requirement to monitor loss of pipe integrity with time and to prevent failures. The use of pipeline steels of increasing strength significantly reduces the threshold hydrogen concentration for hydrogen cracking. Cathodic protection and corrosion processes both contribute to accumulation of hydrogen as a function of time, which may eventually meet the cracking criteria. New and unique methodologies based on electronic property measurements offer the pipeline industry advanced non‐destructive tools to provide quantified in‐situ hydrogen content measurements in real‐time. The use of low frequency impedance measurements as a non‐contact sensor has been demonstrated for real‐time determination of hydrogen content in coated pipeline steel specimens in the laboratory. Scale‐up to field measurements is in progress, and the development and use of a field sensor are discussed.

Nondestructive Evaluation of Uranium: Fundamentals and Future

Nondestructive evaluation (NDE) capabilities have historically been slow to catch on in the processing of uranium, perhaps due to the difficulties associated with its anisotropy and reactivity or perhaps owing to the limited number of uranium applications. Whatever the case, NDE of uranium components has lagged behind the advances in the field for other material systems, despite some of the actinide’s unique properties. A review is presented of the fundamentals supporting NDE techniques as well as the methods themselves which are applicable to uranium systems. Specific features of uranium metallurgy, such as its high degree of anisotropy and low temperature behavior which may be exploited for the purposes of NDE, are described. Finally, case studies in uranium NDE are reviewed briefly in light of the fundamentals established in prior sections.

NONDESTRUCTIVE, NON‐CONTACT HYDROGEN CONTENT ASSESSMENT OF COATED STEEL LINEPIPE WELDS

A nondestructive, non‐contact hydrogen sensor has been developed to assess hydrogen content of coated steel linepipe welds utilizing low frequency impedance measurements. Low frequency impedance measurements are influenced by sources of electron scattering, such as temperature, microstructure, strain, and alterations in the lattice potentials as seen through the effective mass of the conduction electron. Calibration of this sensor must successfully account for these sources of scattering. The effects of coating thickness, weld microstructure, and remanent magnetic field strength on hydrogen content assessment of steel linepipe welds are presented and discussed.

Development of a Novel Electromagnetic Quantitative Residual Stress Sensor for Characterization of Steel Pipeline Mechanical Damage

Nondestructive residual stress mapping of damage in pipeline steel has been demonstrated as a new approach for pipeline integrity management. The handheld system for rapid characterization pipelines has been used on dents and wrinkles, two of the most common forms of mechanical deformation. The ability to compare residual stresses with design stresses will allow for a much more accurate criteria for use in fitness-for-service and improved modeling of pipeline stresses. As the capabilities of in-line inspection technologies continue to improve, operators are often faced with thousands of indications that require examination. Accurate assessment of residual stresses will provide a more effective method of combatting the most common form of pipeline failures, mechanical damage.The residual stresses associated with the mechanical damage forms the basis for the nucleation and growth of cracks at areas with the highest residual stresses. Quantitative, real-time knowledge of the through-thickness residual stress levels associated with the mechanical damage will enable enhanced Risk-Based Inspection and drastically improve pipeline integrity. The development of a non-destructive, quantified residual stress measurement system to evaluate the damage severity on pipeline steels through the structural coatings (without any removal) will enable improved integrity assessment and reduce the number of unnecessary removal and replacement activities. The development of a real-time, through-thickness residual stress sensor to assess steel pipeline mechanical damage is presented in this paper.Copyright

A FUNDAMENTAL ANALYSIS OF LOW FREQUENCY IMPEDANCE PHENOMENON: APPLICATION TO HYDROGEN CONTENT ASSESSMENT OF COATED LINEPIPE STEEL WELDMENTS

Nondestructive hydrogen content assessment of coated linepipe steel weldments via low frequency impedance measurements has been realized both in the laboratory and the field. A fundamental analysis of the plausibility of localized hydrogen‐induced lattice strain detection in linepipe steel through low frequency impedance measurements is presented. Theoretical explanations of low frequency impedance measurements include free electron theory, quantum mechanics, and RKKY theory.

Development of a Non-Contact Hydrogen Sensor for Coated Pipeline Steel Weldments

Only a few parts per million of hydrogen are needed to produce detrimental results in higher strength pipeline steels. The cost of removal and subsequent replacement of a pipeline coating is high; thus a working hydrogen detector for field measurements must operate through the pipeline coating. An in-field sensor must utilize technology that provides rapid (or real-time) non-contact nondestructive measurements. Nondestructive low frequency impedance measurements can be used to determine hydrogen content in operating pipeline steel and weldments as well as through structural coatings. Low frequency impedance measurements have been correlated to hydrogen content in pipeline steel both in the laboratory and in the field. The use of real-time low frequency impedance measurements to monitor hydrogen content in coated steel weldments is presented.© 2010 ASME