NDE, INSPECTION & CONDITION MONITORING | HEAT EXCHANGERS
More efficient heat exchanger inspection
Technical writer, Zetec Inc Stephen Petit
Stephen Petit looks at how automated eddy current workflows can increase the efficiency of heat exchanger inspections
WHETHER THEY ARE IN NUCLEAR power generation or some other industry, nearly every owner or manager of heat exchanger assets faces the same set of issues when they
evaluate their eddy current inspection campaigns: ● Budget and schedule constraints can restrict testing to a small sample size, perhaps as little as 3 to 5 percent of the available tubes.
● Manual analysis of eddy current inspection data is tedious work and subject to human interpretation. Individual analysts can be inconsistent in their ability to identify indications and historical trends, leading to additional downtime and the use of more complex testing methods, like array coil inspections, for greater detection capability.
● Eddy current data analysts are in short supply and need to be as productive as possible. It is a challenge to maintain a team with the proper training, qualifications and experience to analyse and report all the data during the period that the inspection crew has access to tubes and other components.
Any of these factors can cause asset owners to question the overall effectiveness and value of eddy current inspections of heat exchangers. Testing service providers are aware of this, too.
“Our job might entail testing literally tens of thousands of tubes in a window of less than two weeks,” says Marc Brown, Principal Level III and a partner at NDE Technology in Jackson, Michigan, USA, which provides eddy current and other nondestructive testing services for the nuclear power industry in the USA. “We have only so much time to complete the work, yet it’s essential that we’re delivering accurate results quickly and on budget.”
Eliminating a bottleneck Fortunately, Brown says, the latest eddy current probes, handling equipment and instruments can acquire large amounts of inspection data at fast rates. Manually analysing the results, however, is a bottleneck. A typical heat exchanger eddy current inspection involves
an acquisition crew of at least two people: one to handle the probe in the vessel and another to collect the data. After a number of tubes have been inspected, the operator copies the data to a memory stick or other portable device and sends it to the analysis workstation at another location or even off site. When an analyst wants to review the inspection data for
a tube, it might take several minutes to locate the file, open it up and process what he or she sees. Interpretations can vary depending on the analyst’s skill and experience, which can lead to unnecessary down-powers while engineers verify whether or not a tube should be plugged. Automated analysis software is changing this equation.
Automated workflows Developed specifically for heat exchanger inspections in power generation and industrial environments, automated analysis software integrates acquisition, analysis and reporting into a single workflow. The software analyses the data as it is being acquired by the probe operator, loads it into a data management system and can produce a report almost immediately. It can be used in a primary or secondary role or in a single-pass configuration for bobbin, rotating and array inspection techniques, and is capable of distinguishing between circumferential and axial indicators. Automated analysis “eliminates repetitive tasks and
Above: Automated historical data comparison software can retrieve two or more independent data fi les from different inspections and highlight variations Photo credit: NDE Technology
34 | August 2021 |
www.neimagazine.com
streamlines the process for evaluating signals of interest,” says Tom Bipes, project manager for Zetec’s RevospECT and Eddynet software business. “The software can significantly reduce the time from acquisition to reporting so the asset owner can make a more informed and timely decision about repairs and return to service.”
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