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REMOTE FIELD EDDY CURRENT INSPECTION OF UNPIGGABLE PIPELINES

Description: The Remote Field Eddy Current (RFEC) technique is ideal for inspecting unpiggable pipelines because all its components can be made much smaller than the diameter of the pipe to be inspected. We reviewed the technique, and used demonstrations from prior work by others in presentations on the technique and how we plan to develop it. Coils were wound; a jig for pulling the coils through the pipe was manufactured; defects were machined in one six-inch diameter, ten-foot long pipe; and the equipment was assembled. After completing first crude pullout test to show that RFEC inspection would work, we repeated the experiment with a proper jig and got excellent results. The test showed the expected behavior, with the direct field dominating the signal to about two pipe diameters from the drive coil, and the remote field dominating for greater separations between the drive coil and the sensing coils. Response of RFEC to a typical defect was measured, as was the sensitivity to defect size. Before manufacturing defects in the pipe, we measured the effect of defect separation and concluded that defects separated by 18 inches or 1/3rd of the pipe diameter did not interfere with each other. We manufactured a set of 13 defects, and measured the RFEC signals. We found a background variation that was eventually attributed to permeability variations in the seamless pipe. We scanned all thirteen defects and got satisfactory results. The two smallest defects did not show a signal, but these were much too small to be reported in a pipeline inspection. We acquired a ten-foot seam welded pipe that has much less background variation. We are measuring the sensitivity of RFEC signals to mechanical variations between the exciter and sensing coils.
Date: March 1, 2004
Creator: Teitsma, Albert
Partner: UNT Libraries Government Documents Department

DEFECT ASSESSMENT USING CONFORMABLE ARRAY DATA

Description: This first quarterly report of the project presents the activity and conclusions reached to date. Specifically, several of the design parameters of the field eddy current array have been determined and the overall approach to data collection and analysis selected. A kick-off meeting was held at the Clock Spring Company offices, where the project status was presented to the NETL Project Officer.
Date: January 1, 2003
Creator: Crouch, Alfred E.
Partner: UNT Libraries Government Documents Department

Eddy-Current Inspection of a Possible PWR Fuel Element

Description: The following report follows the inspections of a number of eddy-current instrument procedures. The objectives of these tests were to detect both weld defects and lack of integrity of the body of the fuel elements.
Date: August 22, 1955
Creator: Stutz, D. E.; Dickerson, Ronald F.; Wenk, Samuel A. & Gibbs, Richard L.
Partner: UNT Libraries Government Documents Department

Feasibility of eddy current measurement of ferrite content in stainless steel welds

Description: A phase-sensitive eddy current system was used to measure the presence of ferrite in an austenitic stainless steel matrix. Measurements were made on pressed powder specimens and on a weld in Type 304L stainless steel. The data obtained showed that small amounts of ferrite, on the order of 1 to 3%, could easily be detected. Variation in ferrite with position within the weld was also detected with good reproducibility. Absolute values for the ferrite content were not obtained as accurate standards for calibration were not available. (auth)
Date: December 17, 1973
Creator: Lassahn, G. D. & Moment, R. L.
Partner: UNT Libraries Government Documents Department

COMBUSTION TURBINE (CT) HOT SECTION COATING LIFE MANAGEMENT

Description: The integrity of coatings used in hot section components of combustion turbines is crucial to the reliability of the buckets. This project was initiated in recognition of the need for predicting the life of coatings analytically, and non-destructively; correspondingly, four principal tasks were established. Task 1, with the objective of analytically developing stress, strain and temperature distributions in the bucket and thereby predicting thermal fatigue (TMF) damage for various operating conditions; Task 2 with the objective of developing eddy current techniques to measure both TMF damage and general degradation of coatings and, Task 3 with the objective of developing mechanism based algorithms. Task 4 is aimed at verifying analytical predictions from Task 1 and the NDE predictions from Task 3 against field observations.
Date: March 31, 2006
Creator: Gandy, D.; Viswanathan, R.; Cheruvu, S. & Krzywosz, K.
Partner: UNT Libraries Government Documents Department

Reduced Mandated Inspection by Remote Field Eddy Current Inspection of Unpiggable Pipelines

Description: The Remote Field Eddy Current (RFEC) technique is ideal for inspecting unpiggable pipelines because all of its components can be made much smaller than the diameter of the pipe to be inspected. For this reason, RFEC was chosen as a technology for unpiggable pipeline inspections by DOE-NETL with the support of OTD and PRCI, to be integrated with platforms selected by DOENETL. As part of the project, the RFEC laboratory facilities were upgraded and data collection was made nearly autonomous. The resulting improved data collection speeds allowed GTI to test more variables to improve the performance of the combined RFEC and platform technologies. Tests were conducted on 6-, 8-, and 12-inch seamless and seam-welded pipes. Testing on the 6-inch pipes included using seven exciter coils, each of different geometry with an initial focus on preparing the technology for use on an autonomous robotic platform with limited battery capacity. Reductions in power consumption proved successful. Tests with metal components similar to the Explorer II modules were performed to check for interference with the electromagnetic fields. The results of these tests indicated RFEC would be able to produce quality inspections while on the robot. Mechanical constraints imposed by the platform, power requirements, control and communication protocols, and potential busses and connectors were addressed. Much work went into sensor module design including the mechanics and electronic diagrams and schematics. GTI participated in two Technology Demonstrations for inspection technologies held at Battelle Laboratories. GTI showed excellent detection and sizing abilities for natural corrosion. Following the demonstration, module building commenced but was stopped when funding reductions did not permit continued development for the selected robotic platform. Conference calls were held between GTI and its sponsors to resolve the issue of how to proceed with reduced funding. The project was rescoped for 10-16-inch pipes with the ...
Date: September 29, 2006
Creator: Teitsma, Albert & Maupin, Julie
Partner: UNT Libraries Government Documents Department

DEFECT ASSESSMENT USING CONFORMABLE ARRAY DATA

Description: This second quarterly report of the project presents the activity and conclusions reached to date. Specifically, the design parameters of the field eddy current array have been determined and the overall approach to data collection and analysis defined. The data acquisition, display, and assessment software has been completed. A preliminary hardware design was also completed and parts ordered to fabricate a breadboard circuit to validate the concept.
Date: April 1, 2003
Creator: Crouch, Alfred E.
Partner: UNT Libraries Government Documents Department

Emerging NDE Technology for aging aircraft

Description: This paper presents an overview of several emerging nondestructive evaluation technologies that are being employed or considered for use to inspect commercial transport, commuter aircraft and military aircraft. An overview of the Federal Aviation Administration (FAA) Airworthiness Assurance NDI Validation Center (AANC) is described and how AANC teams with industry, universities, and other federal entities to assess these technologies.
Date: March 1, 1998
Creator: Moore, D.G. & Perry, R.L.
Partner: UNT Libraries Government Documents Department

Crack detection on HC-130H aircraft using low frequency eddy current

Description: An eddy current inspection method was developed at the Federal Aviation Administration`s Airworthiness Assurance NDI Validation Center (AANC) to easily and rapidly detect subsurface fatigue cracks in the wheel well fairing on the US Coast Guard (USCG) HC-130H aircraft caused by fatigue. The inspection procedure locates cracks as small as 10.2 millimeters in length at 2.54 mm below the skin surface at raised fastener sites. The test procedure developed baseline three USCG aircraft. Inspection results on the three aircraft reveals good correlation with results made during subsequent structural disassembly.
Date: February 1, 1998
Creator: Moore, D.G.; Mihelic, J.E. & Barnes, J.D.
Partner: UNT Libraries Government Documents Department

Corrosion detection in multi-layered rotocraft structures

Description: Rotorcraft structures do not readily lend themselves to quantifiable inspection methods due to airframe construction techniques. Periodic visual inspections are a common practice for detecting corrosion. Unfortunately, when the telltale signs of corrosion appear visually, extensive repair or refurbishment is required. There is a need to nondestructively evaluate airframe structures in order to recognize and quantify corrosion before visual indications are present. Nondestructive evaluations of rotorcraft airframes face inherent problems different from those of the fixed wing industry. Most rotorcraft lap joints are very narrow, contain raised fastener heads, may possess distortion, and consist of thinner gage materials ({approximately}0.012--0.125 inches). In addition the structures involve stack-ups of two and three layers of thin gage skins that are separated by sealant of varying thickness. Industry lacks the necessary data techniques, and experience to adequately perform routine corrosion inspection of rotorcraft. In order to address these problems, a program is currently underway to validate the use of eddy current inspection on specific rotorcraft lap joints. Probability of detection (POD) specimens have been produced that simulate two lap joint configurations on a model TH-57/206 helicopter. The FAA's Airworthiness Assurance Center (AANC) at Sandia Labs and Bell Helicopter have applied single and dual frequency eddy current (EC) techniques to these test specimens. The test results showed enough promise to justify beta site testing of the eddy current methods evolved in this study. The technique allows users to distinguish between corrosion signals and those caused by varying gaps between the assembly of skins. Specific structural joints were defined as prime corrosion areas and a series of corrosion specimens were produced with 5--20% corrosion distributed among the layers of each joint. Complete helicopter test beds were used to validate the laboratory findings. This paper will present the laboratory and field results that quantify the EC technique's ...
Date: April 25, 2000
Creator: ROACH,DENNIS P.; WALKINGTON,PHILLIP D.; HOHMAN,ED & MARSHALL,GREG
Partner: UNT Libraries Government Documents Department

DEFECT ASSESSMENT USING CONFORMABLE ARRAY DATA

Description: This report covers the design and fabrication of a conformable eddy current array useful for the mapping and measurement of external corrosion on a transmission pipeline. The feasibility of the basic measuring approach was demonstrated and the general guidelines for sensor design were disclosed in a previous project. This project was concerned with design of a practical array, development of interface electronics, and design of the operation and analysis software. A prototype system was constructed, checked out, and demonstrated on natural corrosion in a field environment.
Date: December 1, 2003
Creator: Crouch, Alfred E. & Goyen, Todd H.
Partner: UNT Libraries Government Documents Department

Nondestructive Technique Survey for Assessing Integrity of Composite Firing Vessel

Description: The repeated use and limited lifetime of a composite tiring vessel compel a need to survey techniques for monitoring the structural integrity of the vessel in order to determine when it should be retired. Various nondestructive techniques were researched and evaluated based on their applicability to the vessel. The methods were visual inspection, liquid penetrant testing, magnetic particle testing, surface mounted strain gauges, thermal inspection, acoustic emission, ultrasonic testing, radiography, eddy current testing, and embedded fiber optic sensors. It was determined that embedded fiber optic sensor is the most promising technique due to their ability to be embedded within layers of composites and their immunity to electromagnetic interference.
Date: August 1, 2000
Creator: Tran, A.
Partner: UNT Libraries Government Documents Department

Nondestructive Measurements of Aluminum and Nickel Layers on Uranium

Description: From introduction: "This report covers the development of nondestructive techniques for measuring quantitatively: (1) thickness of electrodeposited-nickel diffusion barriers, and (2) thickness of aluminum cladding on flat-plate fuel elements."
Date: June 12, 1954
Creator: Glaze, E. W.; Rhoten, M. L.; Kulp, B. A.; Cooley, K. D. & Wenk, S. A.
Partner: UNT Libraries Government Documents Department

Combustion Turbine (CT) Hot Section Coating Life Management

Description: The integrity of coatings used in hot section components of combustion turbines is crucial to the reliability of the buckets. This project was initiated in recognition of the need for predicting the life of coatings analytically, and non-destructively; correspondingly, three principal tasks were established. Task 1, with the objective of analytically developing stress, strain and temperature distributions in the bucket and thereby predicting thermal fatigue (TMF) damage for various operating conditions; Task 2 with the objective of developing eddy current techniques to measure both TMF damage and general degradation of coatings and, Task 3 with the objective of developing mechanism based algorithms. Task 4 would be aimed at verifying analytical predictions from Task 1 and the NDE predictions from Task 3 against field observations. Task 5 would develop a risk-based decision analysis model to make run/repair decisions. This report is a record of the progress to date on these four tasks.
Date: March 31, 2004
Creator: Viswanathan, R.; Gandy, D.; Krzywosz, K.; Cheruvu, S. & Wan, E.
Partner: UNT Libraries Government Documents Department

Combustion Turbine (CT) Hot Section Coating Life Management

Description: The integrity of coatings used in hot section components of combustion turbines is crucial to the reliability of the buckets. This project was initiated in recognition of the need for predicting the life of coatings analytically, and non-destructively; correspondingly, four principal tasks were established. Task 1, with the objective of analytically developing stress, strain and temperature distributions in the bucket and thereby predicting thermal fatigue (TMF) damage for various operating conditions; Task 2 with the objective of developing eddy current techniques to measure both TMF damage and general degradation of coatings and, Task 3 with the objective of developing mechanism based algorithms. Task 4 is aimed at verifying analytical predictions from Task 1 and the NDE predictions from Task 3 against field observations.
Date: March 31, 2005
Creator: Cheruvu, S. & Krzywosz, K.
Partner: UNT Libraries Government Documents Department