In-service examinations

Ultrasonic testing method WIT [4, 5], based on ultrasonic wave attenuation measurements at 12 MHz, was used for in-service examinations of the tubes. It is well known that damage to the steel surface and/or degradation of the steel structure changes the attenuation of the waves. Though the WIT method does not show any relation between the attenuation and the mode of steel damage, it reveals deviations from the standard state of the steel. 

The same six tubes of the highest metal skin temperatures were examined every time on the fire-side of the furnace and 3.5 m above the furnace floor. Intensity attenuation coefficients A/ 2 were measured and compared with coefficient = 1 in the as-received steel. Comparing the actual attenuation measurements and the Brinell hardness (HB) measurements with standard characteristics, presumable mechanical properties of the steel including ultimate tensile strength (UTS ) and yield stress at 20 °C were assessed. 

Non-destmctive characteristics of the tube of the highest attenuation coefficients are shown in Table 4.2. It can be seen that the furnace service resulted in a remarkable growth of the intensity attenuation coefficients in the tube. However, the wall thickness of the tube was about the same as in the as-received state and the presumable mechanical properties were within standard requirements [7]. After 11 years of service, the tube was disassembled and put on destmctive testing. 

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Industrial concern for quality and process control, as well as in-service examination, has led to an increased demand for composite reliability inspection techniques. New and more sophisticated NDT techniques have been developed to meet this demand. However, there is still the view that the tried and tested conventional methods are generally more acceptable, their limitations understood and appreciated. Despite the development of new NDT techniques for composite examination, conventional NDT techniques will remain favoured to NDT engineers as they are expected to be accepted more readily [1]. The introduction of innovations, in addition to highly proven and accepted reliabilities in flaw detection, is significantly desirable to composite manufacturers and users. 

Ultrasonic testing of reactor vessel welds during pre-service and in-service examinations (Draft SC 705 pubfished 05/1979) (Rev.l, ML003739996) June 1981 (R 102/1983). 

NDT equipment imported in lots in the process of state testing are examined both on their conformity to the requirements of safety standards (ISO, CEN, lEC) and standards of the manufacturer and its availability for calibrartion in service. 

The hydrostatic test is, in one sense, a method of examination of a vessel. It can reveal gross flaws, inadequate design, and flange leaks. Many beheve that a hydrostatic test guarantees the safety of a vessel. This is not necessarily so. A vessel that has passed a hydrostatic test is probably safer than one that has not been tested. It can, however, stiU fail in service, even on the next appheation of pressure. Care in material selection, examination, and fabrication do more to guarantee vessel integrity than the hydrostatic test. 

Maintenance embraces regular inspection, periodic examination by competent persons , and repairs. Accidents may arise as a result of the lack of maintenance, during maintenance, and as a consequence of faulty maintenance. Preventive maintenance can be a legal requirement for, e.g., pressure vessels/boilers, lifting gear, power presses. A system is required for monitoring compliance witli scheduled preventive maintenance programmes, backed up by in-service inspection. Breakdown... 

A significant portion of design, fabrication and in-service processes and practices are common to all three of these categories of assemblies. These common issues will be explored first, followed by more detailed examination of the genesis and issues particular to each of the three major categories listed above. 

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. 

Outside shutoff valves installed in service lines supplying places of public assembly, such as theaters, churches, schools, and hospitals, shall be examined and serviced, including lubrication where necessary, at sufficiently frequent intervals to assure their satisfactory operation. The examination shall determine if the valve is accessible, if the alignment is satisfactory, and if the valve box or vault, if used, contains debris that would interfere with or delay the operation of the valve. Unsatisfactory conditions encountered shall be corrected. Valves in hydrogen service shall be checked and serviced at least annually. 

AWS C3.3, Recommended Practices for the Design, Manufacture, and Examination of Critical Brazed Components, encompasses those procedures that should be followed in the design, manufacture, and inspection of brazed joints for critical components in order to ensure their reliability in service. 

Another problem is that the design specification is often a combination of extremes and that the actual conditions experienced are likely to have been milder. It is unlikely that conditions will have been monitored. A component which, after years in service, shows no degradation may please the manufacturer, but if after examining the true conditions of service the resulting statement is that no degradation occurred, and none was expected ,... 

Dose-response relations in key primary-producer species in service-important ecosystems should be examined under field conditions. 

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