Nondestructive Evaluation of Materials and StructuresAs an international leader in nondestructive evaluation technology, the Institute provides clients in industry and government with inspection techniques that use such methods as cylindrically guided waves, eddy current technology, and magnetostrictive sensors. The latter technology won the Institute a 1998 R&D 100 award, presented to developers of the year's most significant technical accomplishments.Internal research by SwRI engineers and work sponsored by the Gas Research Institute (GRI) have demonstrated the feasibility of ultrasonic inspection of a gas pipeline, with the signal transmitted through the high-pressure gas itself rather than a liquid couplant. Work is continuing under GRI funding to address practical problems limiting the field application of this technique. If successful, the gas-coupled technique would make it possible to augment or replace the standard, in-line magnetic inspection process with the more accurate ultrasonic method in a gas pipeline.The U.S. Department of Transportation's Office of Pipeline Safety is sponsoring work at SwRI to improve detection and characterization of mechanical damage in transmission pipelines. Working with prime contractor Battelle Columbus and with Iowa State University, SwRI is developing sensor technology that detects deformed material surrounding a damage zone in a steel pipe. This nonlinear harmonic technology has been tested in the laboratory and will be further evaluated in the pipeline environment.SwRI has expanded its in-vessel automated ultrasonic testing (AUT) capabilities to include examination of the threads in the reactor pressure vessel flange. Conventional manual ultrasonic testing is time-consuming, labor-intensive, and hazardous. Combining a threads-in-flange examination with other in-vessel AUT work eliminates the safety issues associated with working with the vessel head suspended over the reactor pressure vessel and reduces the contamination and radiation exposure for examination personnel. This approach also eliminates the need to adjust coolant level and the preparation and training needed to work in the pool floor area. Including the automated threads-in-flange examination as part of the 10-year in-service examination of the pressure vessel greatly simplifies logistics and improves safety.Although considered the most appropriate inspection technology for detecting volumetric defects in materials, ultrasonic inspection is limited by temperature and pressure restrictions and the need for the sensor to be in contact with the material under evaluation. Using internal research funding, SwRI has developed a noncontact, laser-generated, ultrasonic scanning system that can yield useful results even in harsh temperature and pressure environments, as in inspections of hot steel billets and tubular products or in space applications.SwRI recently developed an ultrasonic examination technique to inspect critical welds on the internal fuel support structure of a nuclear reactor vessel. Access to this type of internal weld, designated H8 by industry engineers, is extremely difficult. In the new technique, the ultrasonic beam travels through the exterior reactor vessel wall and approximately 24 inches of steel plate to reach the target H8 weld. SwRI and Wesdyne International used a full-size mockup of the vessel component, seeded with known flaws, to qualify the technique according to industry guidelines. Following qualification, field examinations were successfully conducted at two U.S. plants.A rapid pipe inspection system, developed at SwRI, was selected among the year's 100 most significant technical accomplishments by R&D Magazine. Magnetostrictive sensor (MsS) technology provides a fast, cost-effective means of inspecting steel pipes and tubes in processing and power-generating plants for the oil, gas, and chemical industries. MsS launches elastic waves in frequencies up to several hundred kHz and detects signals reflected from any defects, such as corrosion or cracking. The technique provides 100 percent volumetric inspection, can examine several hundred feet of pipe from a single sensor location, is noncontacting and thus needs no couplant, and does not require removal of pipe insulation, except for a few feet of insulation for sensor placement. Defects as small as 1 percent of the cross section can be detected, as can localized wall thinning.SwRI is developing an eddy current method for measuring the thickness of erosion-resistant coatings applied to blades used in gas-expander turbines. This technique determines that the proper coating thickness has been applied during production and that it has not been compromised by in-service wear. Here, the coating thickness is being measured prior to turbine installation.

Institute scientists have extended the capabilities of MsS technology for faster, lower-cost inspections of heat exchanger tubing for the petrochemical and power industries. While present ultrasonic and eddy current inspection methods require the tube interior to be thoroughly cleaned and the inspection probe to be moved the full length of the tube, a guided wave generated from a special MsS probe, inserted 6 to 12 inches inside the tube, permits effective examination of the entire tube. This technology requires that only the tubing contacted by the probe be cleaned.The industry's standard method of detecting erosion or corrosion within pipes and fittings is to perform periodic ultrasonic testing (UT). Ideally, each inspection measures the same spots on the pipe so that successive data from these locations can be compared to determine the rate of degradation. To automate this time-consuming and labor-intensive process, the Electric Power Research Institute (EPRI) tasked Institute engineers to develop a UT system to automatically identify uniformly spaced surface locations on straight pipe and on pipe elbows, tees, and reducers, at which wall thickness is to be measured. The Institute-developed system permits the inspection grid to be defined on piping components with compound curvature in minutes, rather than up to two hours using previously required techniques. The system then emits and detects acoustic ranging signals to locate inspection grid points, records ultrasonic signals, and organizes the inspection data into a suitable format for analysis. The newly developed system improves position location measurements, increases examination repeatability, and is compatible with the EPRI-developed CHECWORKS analysis program.Under contract with the Electric Power Research Institute, SwRI engineers automated a labor-intensive method of identifying and tracking locations on piping and fittings undergoing periodic ultrasonic testing. The Institute-developed method permits an inspection grid to be defined on piping components in a fraction of the time previously required.

In a project jointly sponsored by a group of major oil companies and EPRI, Institute engineers developed a real-time, filmless, digital radiography system to detect corrosion in insulated piping systems. The system fits over the insulation, eliminating the need to remove even the small amount of insulation required to use MsS technology. The radiography system scans the entire surface area of the pipe with a solid-state linear detector array to measure radiation from a low-intensity iridium gamma ray source positioned opposite the moving detector. In contrast, MsS evaluates the entire pipe from a stationary point. The radiography system is expected to be especially useful in the refining, chemical processing, and power-generation industries.SwRI is working with the Central Research Institute of the Electric Power Industry of Japan to advance the ability to predict and characterize degradation in modern gas turbine engine blades. Modern engines are designed with new materials to operate at higher temperatures for better thermal efficiency. However, these temperatures degrade the protective coating on the blades and their base material, severely limiting the service life of the turbines. In this two-year program, SwRI has prepared specimens to represent modern blade material with an MCrAlY coating and is subjecting them to degradation processes that represent in-service conditions. SwRI is performing a series of destructive and nondestructive tests to develop models that can predict in-service degradation and to improve electromagnetic and ultrasonic inspection methods.SwRI and Engineering Data Management, Inc., under EPRI funding, are developing technologies that can remotely monitor in real time the sag in high-voltage electrical transmission lines. Transmission lines often have spans of 500 feet or more between towers. As more power is transmitted through the lines, resistive heating causes the line to elongate and then sag. It is important that the line not sag below its allowed ground clearance. New technologies being studied allow the electrical power transmission industry to monitor the sag of the line in real time and thus optimally and safely transmit all needed power, even during peak loads. Under laboratory conditions, SwRI has measured line sag with an accuracy within one-half inch per 500-foot span or better. The Institute is conducting limited field evaluation to determine the robustness of the technology.Copyright 1998 by Southwest Research Institute. All rights reserved under U.S. Copyright Law and International Conventions. No part of this publication may be reproduced in any form or by any means, electronic or mechanical, including photocopying, without permission in writing from the publisher. All inquiries should be addressed toCommunications Department,Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510, phone (210) 522-2257, fax (210) 522-3547.

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