Rainer Semmler, head of process safety management, TÜV SÜD Industrie Service and Hermann Schubert, head of digital and continuous Inspection, TÜV SÜD Industrie Service explains how in pharmaceutical manufacturing, both sterility and uninterrupted operations are essential – this poses challenges when it comes to component monitoring.
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Acoustic Emission Testing (AT) offers a non-invasive way to assess system integrity without halting production or breaching cleanroom conditions. Moreover, the use of AT improves safety verification while enhancing system uptime. TÜV SÜD illustrates how this method works and how plant operators in pharma can use it to achieve considerable savings without neglecting compliance and efficiency.
Ensuring the integrity of pressurised equipment, storage tanks, and other safety-critical systems is non-negotiable in the pharmaceutical industry. Regulatory guidelines thus mandate recurring inspections of such components. Traditionally, this involves testing methods such as visual assessments or hydrostatic testing, which often require systems to be shut down and partially dismantled.
Moreover, both visual and hydrostatic testing pose a risk of contamination: for visual assessments, auditors must enter and inspect tanks manually, causing previously sterilised areas to be re-exposed to pathogens. As for hydrostatic testing, fluids are pumped into the system to test its resilience under pressure, resulting in downtime and extended drying periods. In pharmaceutical environments, these drying phases are particularly sensitive. Residual moisture, even in trace amounts, can become a breeding ground for microbial growth, compromise stainless steel surfaces through corrosion, and ultimately threaten batch integrity. While in different ways, both approaches interrupt production and trigger energy-intensive stop-and-start procedures.
AT: Traditional testing methods shift course
AT’s major advantage: testing can take place while the system is running, with almost no interruption to production. This is because specially designed piezoelectric sensors are affixed externally to tanks, reactors, and integrated machines such as pumps, compressors, or motors, therefore eliminating the need for invasive testing. When cracks or material deformations begin to arise, they generate characteristic acoustic signals in the form of transient elastic waves. The sensors pick these signals up, allowing conclusions to be drawn about potential defects or weaknesses. Simultaneously, they provide insights into parameters such as flow characteristics or mixing performance.
The analysis of acoustic signals enables early detection of damages and can be followed up by planned repairs rather than emergency interventions. Acoustic Emission Testing is recognized as a valid alternative to conventional techniques, when applied as part of an approved testing concept. The concept needs to be aligned with regulatory guidelines and confirmed by safety authorities.
Telling the future
An additional benefit of AT is its role in implementing predictive maintenance strategies. Because the method enables early identification of defects such as cracks or corrosion, plant operators can be simultaneously proactive and reactive in responding to equipment issues. In the pharmaceutical sector, this minimises the risk of sudden failures that could lead to batch loss or regulatory violations.
Planning repairs in advance not only reduces unexpected downtime but also contributes to the long-term durability of critical equipment. Systems are subjected to fewer full shutdowns and restarts, which translates to reduced mechanical stress and energy consumption. The cumulative effect: increased reliability and lower annual maintenance costs compared to traditional inspection practices.
Smarter inspections, Smarter combined
With AT, because of the flexible external sensor installation, simultaneous data collection, and real-time monitoring, entire system segments can be monitored in parallel. This makes it a powerful tool for plant operators looking to streamline inspection efforts. This not only reduces the time required for testing but also allows for a leaner team, freeing up skilled personnel for other tasks. In production settings with distributed or multiple systems, this feature translates directly into efficiency gains across both time and labour budgets.
Furthermore, AT can be combined effectively with other non-destructive testing (NDT) methods. When preliminary AT results suggest a potential defect or weakened area, targeted follow-up testing — such as ultrasonic or radiographic inspection — can be applied specifically where it’s needed. This layered approach ensures that resources are focused and downtime is minimised.
Conclusion
When comparing the direct cost of AT to traditional testing methods, the numbers may not immediately suggest a dramatic difference. However, the broader picture tells another story. The real savings come from avoiding preparation and post-processing steps, therefore reducing avoidable risks as well as material wear.
Beyond its efficiency, the method also supports more sustainable operations. AT eliminates the need for potentially contaminated test fluids and the associated disposal. Cleaning requirements are reduced, energy consumption drops, and the environmental impact is minimised. As customers place increasing value on clean and traceable production processes, these advantages can give companies a measurable edge in competitive markets. TÜV SÜD not only delivers Acoustic Emission Testing as a service but also provides operators with the tools and insights needed to weigh inspection strategies early, optimise resources, and avoid surprises. In short: smarter testing now means fewer disruptions later.