There is need to intensify initiatives to raise awareness about the application of PAUT NDT Testing amongst operators to foster adherence to best practice in projects.
Phased Array Ultrasonic Non-Destructive Testing (PAUT) has revolutionised how inspection and testing of critical equipment is performed in power generation, mining, oil, gas and other industries. Fascinatingly, in comparison with conventional techniques, with PAUT, complicated tasks are accomplished effectively in no time, enabling predictive and preventative maintenance to be implemented timeously, minimising downtime.
On the other hand, it has been noticed that the technique is sometimes misunderstood, leading to misapplication. Consequently, Mark Digby, NDT Training Manager at the Southern African Institute Welding (SAIW), says it is vital that end-users in industries are well-versed with fundamentals of PAUT.
SAIW has identified common misunderstandings amongst operators after conducting a survey on end-user awareness on the appropriate applications PAUT NDT equipment, predominantly:
- PA units are more expensive to purchase than are conventional UT sets
- One probe doesn’t suit all applications;
- Operation and data interpretation are more difficult;
- There can be greater difficulty in achieving good ultrasonic coupling due to the larger probe dimensions. Thus, difficult to get to areas can be problematic;
- Additional UT training especially on the different makes of UT PA machines is necessary.
- Phased Array can do everything !!!!!!!!!!!!!
Best practice in the application
Bearing in mind the abovementioned scenario, Digby acknowledges that there is need to intensify initiatives to raise awareness amongst operators to foster adherence to best practice in the application of PAUT in projects.
Drawing attention to what industry can benefit from PAUT through better awareness, he explains: “Ultrasonic phased array systems can potentially be employed in almost any test where conventional ultrasonic flaw detectors have traditionally been used. Weld inspection and crack detection are the most important applications, and these tests are done across a wide range of industries including aerospace, power generation, petrochemical, metal billet and tubular goods suppliers, pipeline construction, maintenance, structural metals, and general manufacturing. Phased array can also be effectively used to profile remaining wall thickness in corrosion survey applications.”
In a nutshell, the benefits of phased array technology over conventional UT come from its ability to use multiple elements to steer, focus and scan beams with a single transducer assembly.
Essentially, the effectiveness of PAUT NDT testing and inspection helps industry forestall unscheduled repair and replacement expenditure on equipment components.
Progressive deterioration of materials by chemical or electrochemical reaction with their environment is recognised as one of the most significant problems, which results in hundreds of millions of revenue losses each year.
“Corrosion or erosion impairs strength, appearance and impermeability to gases and liquids in materials and structures. Several industries have recognised that ‘not having’ effective corrosion management is too expensive, and that substantial cost savings are possible through NDT especially Phased Array UT inspection of critical assets,” states Digby.
The training of operators
Clearly, the significance of training personnel involved in PAUT inspection and handling PAUT equipment to build capacity should not be overstressed. Specifically, the following are critical areas recommended in the training of operators:
- Principles of Phased Array probes
- Principles of inspection sensitivity
- Phased Array Instruments
- Scanning with Phased Array probes
- Calibration and checks
- Software for data collection and data analysis
- Principles of data analysis
- Software familiarity
- Use of software tools for defect detection and sizing
- Data analysis
- Procedures for verification of flaw existence and position
Keeping abreast of latest developments
As NDT technology continues to grow, accelerate and change ultrasonic testing, service providers must keep abreast of latest developments to remain relevant in today’s fast paced world, underscores Digby. “Welding inspectors recognise that time is really important especially during outages. And so, they require the highest performance tools to produce reliable and repeatable volumetric data collection results. At the end of the day, you are compelled to deliver a welding defect inspection report faster than the other guys with absolute confidence in your assessment.”
The Total Focusing Method technique (TFM) is receiving more and more interest in the industry. Due to its high focusing capabilities, the technique leads to optimum spatial resolution and improved sensitivity for the improved detection of small indications. Recently included in standards, such as ASME V, and will continue to get more attention as developments continue.
As far as possible, it is important that accurate data is gathered from PAUT NDT inspection and testing. For this reason, it is requisite for PA end-users to have common software to analyse files saved by different equipment without retraining inspectors on different software applications, emphasises Digby.
He adds that it is vital that OEM’s work towards implementing a common storage format to eliminate data conversion and obsolescence issues. “The flexibility of multiple data representations and merging big datasets for large parts are valuable tools to make accept/reject decisions of parts being inspected.”