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Automated ultrasonic tube-to-tube sheet weld scanning
Tube-to-tube heat exchangers are critical for plant operations , current inspection methods primarily focus on surface checks , overlooking internal defects that could compromise safety and production . To address this gap , FORCE Technology has developed an automated ultrasonic solution capable of efficiently detecting embedded defects within welds and providing detailed documentation .
By Jens Peter Bertelsen , Project Manager at FORCE Technology
Tubesheet Welding
About the author
Jens Peter Bertelsen have been working at FORCE Technology for 20 years and is responsible for inquiries concerning Eddy Current- , Iris- , Long Rangeand Tube-to-Tube sheet ( TTS ) weld inspections and do often make the inspections at sites .
Heat exchangers are critical components in many chemical processing plants . Their safe and reliable operation is an important issue for the operators . Currently , inspection of the tube-to-tube sheet welds in the heat exchangers is normally limited to various methods for surface inspection , while defects inside the welds remain undiscovered , which could compromise safety and could lead to failure and production stops . To overcome this issue , FORCE Technology has developed an automated ultrasonic solution , which is capable of finding small , embedded defects in the welds , is time efficient and provides detailed documentation of the inspected welds . This paper describes the company ’ s solution and how we apply it .
Introduction Inspection of tube-to-tube sheet welds are traditionally limited to visual , liquid penetrant and hydrogen leak testing . All these techniques only provide information about the surface condition of the inspected welds , such as surface cracks or other surface breaking discontinuities . The mentioned inspection techniques are not able to detect any internal weld defects such as lack of fusion or cluster porosity . Internal defects are crucial for weld integrity . FORCE Technology has developed an alternative technique based on standard ultrasonic examination principles , which can detect them . The technique offers a lot of benefits for their customers and significantly increases the level of confidence they have in the examined heat exchangers . The technique is very fast , thus minimising downtime and provides full scanning of the welded volume . Therefore , defects such as lack of fusion , inclusions or clustered porosity are easily detectable . The technique makes it possible to save detailed data for each particular weld , including precise dimensioning and positioning of detected defects inside the weld . The data can either be used for on-site reporting or , if needed , at a later stage . The equipment is easily transportable and does not require any safety preparations prior to testing , except for those required by the customer .
Ultrasonic NDT technique The technique is making use of normal ultrasonic testing principles but is applied with a specially designed scanner . It can scan the weld for internal indications in the full weld
The weld inspection principle . Image courtesy of FORCE Technology .
The tube-to-tube sheet scanner . Image courtesy of FORCE Technology .
length , a 100 % circumferential area and to size eventual indications . Internal indications such as lack of fusion , cluster porosity , inclusions and cracks are easily detectable . The ultrasonic probe is positioned in the scanner ’ s hollow shaft and inserted into the inspected tube in the heat exchanger . The probe is rotated and translated axially simultaneously , thus performing a screw spiral movement . Inspection starts and stops a couple of millimetres before and after the weld , respectively . A centring mechanism is keeping the inspection head centred in the tube . The specially designed scanner enables fast and accurate inspection of the weld . Inspection rate is between 60 and 90 welds per hour . Below the weld inspection principle is illustrated .
Automated data collection Data collection is based on FORCE Technology ’ s automated ultrasonic inspection system , called P-scan . The system was first developed by the company in the 1970s and has since been under constant development and improvement . The system can be applied in many areas and its further development is based on regular use and accumulated field experience . Furthermore , we have developed a wide range of scanners , based on the P-scan system , adaptable to specific www . heat-exchanger-world . com Heat Exchanger World June 2024
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