Pulsed Eddy Current Inspection of Support Structures
in Steam Generators
بازرسی جریان گردابی پالسی برای سازه های نگهدارنده در ژنراتورهای بخار
ABSTRACT
Degradation and fouling of support structures in nuclear steam generators (SGs) can lead to SG tube damage and loss of SG efficiency. Inspection and monitoring of support structures combined with preventative maintenance programs can alleviate these effects and extend SG life. Conventional eddy current inspection technologies are extensively used for detecting and sizing indications from wall loss, frets at supports, cracks and other degradation modes in the tubes, as well as assessing the condition of support structures. However, these methods have limited capabilities when more than one degradation mode is present simultaneously, or when combined with fouling. Pulsed eddy current combined with principal components analysis (PCA) was examined for inspection of 15.9 mm (5/8") Alloy-800 tubes and surrounding stainless steel (SS410) support structures. Clear separation of PCA scores associated with tubes from those associated with ferromagnetic SS410 supports permitted measurement of tube-to-support gaps, in either the presence of tube fretting or variation of relative position of the tube within SS410 supports. For concentric tubes, frets could be sized independently of SS410 hole diameter variations, which in other materials could represent support corrosion. Capability to clearly separate scores was attributed to large differences in relaxation times for diffusion of transient fields through the tube compared with diffusion into the ferromagnetic support structure.
Advances in NDT and materials characterization by eddy currents
پیشرفت هایی در NDT و مشخصه یابی مواد توسط جریان گردابی
ABSTRACT
Non-Destructive Testing (NDT) plays a vital role to achieve reliability and quality at an acceptable cost. Failures of engineering materials, components and structures are well known and can be disastrous [1]. Avoiding the failures cost effectively ensuring safety of use and reliability on a wide range of industrial components are the major industrial NDT objectives. NDT is facing new challenges for defect detection and quality control of advanced engineering materials such as in multi-material structures [2], non-ferrous alloys for advanced lightweight structures, composites [3] (GLARE), carbon resins composite, Fiber-reinforced Metal Laminates (FML), High Performance Thermoplastic Composites (HPTC) and Metal Matrix Composites (MMC)). In the scope of recent production technologies: Friction Stir Welding (FSW), Friction Surfacing, Friction Stir Processing (FSP) and Single Point Incremental Forming (SPIF), innovative NDT techniques and technologies are required, and must be transfered from research to industry as quickly as possible to solve these challenges.
Evaluation of crack depth using eddy current techniques
with GMR-based probes
ارزیابی عمق ترک با استفاده از تکنیک های جریان گردابی با پروب ها بر پایه - GMR
ABSTRACT
This paper presents experimental and simulated results obtained using the eddy current nondestructive method to conclude about the depth of linear cracks machined on an aluminum plate. Experimental tests were performed with a sinusoidal excitation field of fixed-amplitude and with a giant magnetoresistance-based sensor to measure the resultant magnetic field on the plate surface. To validate and better insight the experimental results, numerical simulations have been carried out with a commercial program for conditions similar to the experimental case studies. A scheme to infer about crack depth is proposed.
Eddy current sensors
سنسورهای جریان گردابی
ABSTRACT
In addition to tavtile ( gauging ) sensors, non contantct metrology is now also used to measure displacement, deformation,, stretching, distances, position and other geometrical shapes and sozes. These sensors often measure faster, more accurately and more reliably than tactile sensors. The measurement data is normally available in real time to automatically regukate and control the production. Quality control is not only carried out on finished products, but metrology can also supervise and optimize production processes. The aim is to improve product quality, reduce rejects to a minimum and to lower total production costs.