Thermography-Excellent tool for Condition Monitoring in Industries

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1 More Info at Open Access Database Thermography-Excellent tool for Condition Monitoring in Industries I. Maria Michael Raj 1, a and R.D.Patel 2,b 1 Engineer in Charge, ISI & QA, Heavy Water Plant, Kota, India 2 General Manager, Heavy Water Plant, Kota, India a michaelrajim@gmail.com, b gm@kot.hwb.gov.in Key Words: Ageing management, Degradation, NDT, Thermography, Condition monitoring, Life Extension ABSTRACT Condition monitoring / Ageing management of plant pressure components is a challenge encountered by industires today for increasing the life of components.condition management must ensure that pressure components are healthy and function as per design specifications. Upsets in operating conditions either alone or in combination with the environmental factors may lead to degradation of the materials. Several Non Destructive Techniques are available for assessment of health of static and rotating components. Infrared Thermography is also a non destructive technique and one of the important diagnostic tools for predictive condition management in electrical, petrochemical, steel and other process industries.it is non contact, non intrusive and can be applied to wide range of systems including high temperature ammonia converter, components in reformers/ crackers, insulated equipments, electrical components and steam network. This paper deals with the principle and applications of Infrared thermography for condition monitoring, energy conservation and life extension of components in process industries.components covered with vast energy saving potential include cracker/reformer furnace, super alloy tubes containing catalyst, Super heater and Ammonia converter, bearings, casings and gearboxes of pumps, compressors & blowers,components in Electrical Distribution Network including motors, circuit breakers,insulation and Refractory heathiness assessment.as with any non destructive technique Infrared thermography has a few limitations such as Standardization and Emissivity correction but suitable training/calibration can easily overcome the limitations. Introduction Any process industry needs a huge investment of hundreds of millions with considerable gestation period and is designed for a limited service life. Improved technologies and higher quality materials have today contributed to certain extent in reduction of gestation period and availability of more corrosion resistant materials. However, condition monitoring / management of plant pressure components is a challenge encountered by the designers today for increasing the life of components. It has been established that sustained operation of any industry with effective condition management and without breakdown of critical components has reduced the operating cost and increased the plant life. It is no secret that even an extension

2 of a few years of life over the original design life of fifteen or twenty years will lead to significant improvement in the profit margin considering the present cost of any new equipment. Condition management must ensure that pressure components are healthy and function as per design specifications. Any degradation observed in pressure vessels, piping, structures and other components must remain within acceptable limits. It is practically impossible to maintain precisely various process parameters such as pressure, temperature, composition and flow, affecting the pressure components as per design intent. Occasional upsets in operating conditions may result in deviation from design parameters These deviations either alone or in combination with the environmental factors such as ambient temperature, humidity and air quality may lead to degradation of the materials. Various degradation mechanisms such as corrosion, fatigue, cracking, creep and brittle fracture may reduce the life of the components and cause premature failures. Several Non Destructive Techniques including visual inspection, dye penetrant examination, ultrasonic examination, thickness measurement, acoustic emission test, leak test, vibration analysis, hardness test and metallography are available for assessment of health of static and rotating components. They are essential tools to identify any initiation of degradation in time and monitor its growth for timely repair/ replacement of defective components (1). Infrared Thermography is also a non destructive technique and one of the important diagnostic tools used internationally for predictive condition management and energy conservation in electrical, petrochemical, steel and other process industries. However,Infrared Thermography is an innovative technique different from other conventional Non Destructive techniques since it is non contact, non intrusive and can be applied to wide range of systems including high temperature ammonia converter, components in reformers/ crackers, insulated equipments, electrical components and steam network. This paper deals with the principle and applications of Infrared thermography for condition monitoring, energy conservation and life extension of components in process industries. Principle: Infrared Thermography is a technique for non-contact mapping of spatial distribution of heat and measurement of temperature. It operates on the principle of sensing infrared radiations emitted by any object above the Absolute Zero temperature. Using an infrared detector, it is possible to convert these radiations into electrical signals which can then be displayed on a monitor as a grey level image or colour image, representing the complete surface temperature map of the object. Infrared radiation is invisible to human eye at temperatures below 525 C. Thermography extends the range of human vision into the infrared region of spectrum and permits the presentation of thermal images in real-time. The human visual sense is not only extended, it is also supplemented by quantitative analysis of the images to provide an accurate temperature measurement and identification of isotherms. Infrared camera is a real time thermal imaging system for temperature measurement and analysis, of both dynamic and static thermal patterns. The detector unit converts infrared radiation emitted by the object into

3 an electrical video signal. The surface of the object is scanned to produce a real-time thermal image of the object. Thermal images are produced at safe distance from the structures or items of interest, and no contact or linkage with the object is required. This important feature of thermography is of great importance when high temperature and dangerous gases, liquids or fumes are present. Thus thermography not only produces high quality images, but is also optimised to provide accurate temperature measurement of objects with very fine temperature detail. Infra-red band has a range of µm but normal observations are done in a spectral range of 2-6 µm. Thermography can be applied both in active and passive mode. When we monitor the heat radiated by a hot object it is passive thermography.. We can also induce heat in a cold object and monitor the variations on the entire surface of the object for detection of any inhomogenity in structure. The latter method is widely used in integrity assessment of electronic industries and is called Active thermography. Temperature is one of the first observable parameters that can indicate the condition of operating equipment. With ageing, components and contact surfaces of the system will begin to deteriorate. With the deterioration comes increased resistance and with resistance, increased heat. Fluctuating and high loads, vibration, metal fatigue, age and specific operational environments can contribute to such degradation. All equipment, when operating under regular conditions, have their own operating thermal signature, Infrared thermography identifies this normal signature as a baseline and will detect the thermal variances deviating from the norm. This localized thermal deviation may be caused either by an overheated condition or by absence of heat Applications for Health assessment& Condition Management Infrared thermal mapping and imaging of high temperature components such as cracker/reformer furnace, super alloy tubes containing catalyst, Super heater and Ammonia converter for identification & prevention of overheating and consequent damage due to Hydrogen induced cracking, creep etc. Bearings, casings and gearboxes of pumps, compressors and blowers can be inspected by thermography during periodic condition monitoring and corrective maintenance taken where needed to prevent potential failure. Thermography is being used as a predictive maintenance tool on components in Electrical distribution network including motors, circuit breakers, switchgears, connectors, switches, buses and insulators of switchyard to identify hot spots. Thermal mapping of Refractory wall of cracker furnace, identification of hot spots due to weakness in refractory lining, loose bricks etc. We have taken up refractory repair in opportune shut downs with recovery of heat loss. The thermal efficiency of insulation material can be determined by thermography. Thermal mapping/ imaging of hot/ cold insulation on equipment and piping can be done to identify weakness in insulation.

4 Hot spots motor bearing at DE and NDE Infrared thermal mapping and imaging of high temperature cracker furnace, K K

5 Faulty Gear Box Of An Exhaust Blower Advantages derived by HWPs Sustained operation with continual improvement in downstream efficiency. No major breakdown or sudden failure of any component in service. Commendable reduction in Energy consumption by more than 13% Several prestigious awards from Ministry of Environment and premier institutions such as Atomic Energy Regulatory Board and National Safety Council. Conclusion Thermography has got unique distinction among NDT techniques because of its fast results, adaptability to inspect hostile/ inaccessible areas, freedom from unsafe radiations, ability to provide full field images and provide both qualitative and quantitative information on the inspection. As with any non destructive technique Infrared thermography has a few limitations such as Standardization and Emissivity correction, interference of variables such as flame, smoke, thermal losses etc. However, proper correction and suitable training can easily overcome the above limitations. References (1).. Code of Practice for inservice Inspection of Heavy water Plants by Heavy Water Board,Department of Atomic Energy,Rev.1