Sagadevan Kanniappen from WIKA presenting at the March technology evening.
The SAIMC Secunda branch held its monthly Technology Evening on 6 March 2024 at the Proconics, Secunda office. Sagadevan Kanniappen from WIKA presented on Thermowell stress calculations as per ASME PTC 19.3. His focus was mainly on wake frequency calculations and the requirements for debottlenecking projects. He also discussed the data needed for thermowell design and presented a case study on the decommissioning of the Japanese Monju nuclear power plant. The plant was shut down after only three months of operation due to thermowell failure.
In his presentation, he gave a short overview of the ASME PTC 19.3 standard. The standard was initially established in 1974 and was reaffirmed in 1986. In 1995, the Monju nuclear power plant experienced a thermowell failure. After conducting a root-cause analysis, it was discovered that the failure might have been caused by inline resonance, which was not considered in the standard at the time. Subsequently, the standard was revised to account for this potential cause of failure. It was revised again in 2010 and 2016.
Sagadevan explained the concept of wake frequency calculations. To prevent any damage to the thermowell caused by mechanical loads during operation, it is recommended to perform a wake frequency calculation as per ASME PTC 19.3 TW-2016 for critical process conditions. These calculations require basic process conditions like the process medium, density of the medium, maximum working temperature and maximum working pressure. Wake frequency calculations can be done manually or through online tools offered by the original equipment manufacturers (OEMs). Sagadevan emphasised the importance of performing manual calculations to comprehend the software’s working, despite the convenience offered by online tools.
Thermowells can be impacted by debottlenecking projects. When a wake frequency calculation is performed, it is based on specific process data, and the results determine whether it passes or fails. If there are changes to the process data, such as during debottlenecking projects, the wake frequency calculation must be redone. The failure to adhere to PTC 19.3 can have catastrophic consequences for both human life and the environment.
The Secunda SAIMC committee would like to thank Sagadevan Kanniappen for his time and presentation, and Proconics for hosting the monthly technology evenings.
Any companies interested in presenting at the Secunda Branch monthly technical talks can complete this form: https://forms.office.com/r/f5QXNLcDDt or contact the branch general manager, Lezahn Meiring at gm_secunda@saimc.co.za
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