Reliability

ect MAD 8D RELEASE 8.00
Version 8.00 of the ect MAD 8D software in all option configurations is now available. With the release of Version 8.00, we have changed the product name from MAD 4D to MAD 8D. This name change was necessary because the number 4 is very unlucky in most Asian countries. The number 4 is so unlucky that many hotels do not have a fourth floor. The number 8 means prosperity.

THOUSANDS OF INTERNAL PITS IN HEAT EXCHANGER TUBING
When pitting occurs in heat exchanger tubing, usually there are hundreds or thousands per tube. The task of manually examining the eddy current response to each of these signals in order to determine the deepest defect in a tube is immense.
Computer-aided, automatic sizing of these defects is the answer. For further information, please request the report AUTOMATIC SIZING OF INTERNAL PITS IN HEAT EXCHANGER TUBING USING EDDY CURRENT.

WHY DO SOME EDDY CURRENT INSTRUMENTS FAIL?


A few weeks ago I read an article in Electronics News that expressed concern about the shortage of, and rising price of, electrolytic tantalum capacitors. The article went on to express concern that as a result, some computer motherboard manufacturers were using the less expensive and more readily available aluminum electrolytics as the power supply bypass capacitor for the microprocessor.
Microprocessor manufacturers recommended the use of a tantalum capacitor. The article pointed out that tantalum capacitors have better performance specifications than aluminum electrolytics. Furthermore, aluminum electrolytics begin to degrade from the day that they are manufactured; whereas, there is no known degradation mechanism for tantalum capacitors. At Eddy Current Technology Incorporated, we have never put an aluminum electrolytic capacitor in any product. We have always used tantalums, but not just any tantalum. We have never used the cheaper, epoxy dipped tantalums; but instead, as a minimum, we have always used a hermetically sealed MIL style CSR13 capacitor (the R in CSR13 stands for established reliability) designed to MIL SPEC MIL-C-39003.
The tantalums we use are rated for full performance over an operating temperature range of -55° C to +85° C and yet we still derate them. That is to say when we choose a capacitor for a specific application, we will choose one with a voltage rating which is at least 25 per cent higher than the operating voltage in the circuit.
After all that, we still burn in the finished product prior to shipping it to the customer. These are all reasons why we get reports of reliable performance of our products from the snow country of Canada to the heat of Saudi Arabia.
We may pay more for our electrolytic capacitors than our competitors, but there is payback. In 18 years of business, we have had only one field failure of an electrolytic capacitor. This was entirely our fault. We installed it incorrectly. Since that time, we have added an additional inspection which is performed immediately after burn in, which has successfully prevented us from making this mistake a second time. No customer has ever paid a repair charge to replace an electrolytic capacitor in a product manufactured by Eddy Current Technology Incorporated.
If an electronic product is designed and manufactured correctly, it should never fail, and there is no need for an Owner/Loaner Guarantee.

DETECTION OF CIRCUMFERENTIAL CRACKS IN HEAT EXCHANGER TUBES


The detection of circumferentially oriented cracks in heat exchanger tubing is difficult to detect with the usual bobbin probes for two reasons.
1. The bobbin coil creates eddy currents in the tube wall which flow in the circumferential direction; therefore, they pass a circumferential crack without having to cross its crack face. This gives a low sensitivity to this defect type.
2. Most circumferential cracks are located adjacent to support structure or an expansion transition, both of which create a very large signal, masking the small signal from the crack. Circumferential cracks occur in several heat exchanger applications as follows:
1. At the tube sheet expansion transition zone in nuclear steam generators.
2. On bends that occur in nuclear steam generators at the top of the sludge pile.
3. In nuclear steam generators at the top edge of the top support plate.
4. In titanium condenser tubes at the tube sheet expansion transition zone when the tube was overrolled in the tube sheet.
5. In finned copper tubing (integral fin) used in air conditioners. The crack initiates from the root of the fin and may or may not be in an expansion transition zone, but even away from expansion transition zones, the tube has high background noise, masking the signal from the crack.
6. Fatigue cracks mid-span between support plates on the peripheral tubes of titanium condensers.
In 1983, Eddy Current Technology Incorporated designed the first probe in the world that was capable of detecting circumferential cracks at a tube sheet expansion transition zone. The probe design canceled signals from expansions, support plates, and tube sheets, while increasing sensitivity to circumferential cracks by having current flow in the longitudinal direction in the tube, so that the current flow would pass over the crack face. For further information on this subject, please request the report DETECTION OF CIRCUMFERENTIAL CRACKS IN HEAT EXCHANGER TUBES..