FCTM Esope

S2.5 - Heat Exchanger Tube Rupture Credibility Assessments (TRCAs)

Oct 6, 2021 | 2:30 PM - 3:00 PM

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Description

When designing pressure relieving systems for heat exchangers, the potential for internal tube failure needs to be considered, particularly if there is a significant difference in design pressure between the shellside and tubeside of the exchanger. As part of pressure relief system design, the tube rupture scenario needs to be assessed when the low pressure side of an exchanger can be significantly overpressured in the event of a tube rupture. API 521 “Pressure-relieving and Depressuring Systems” provides guidance on this topic and treats this scenario somewhat differently than other credible overpressure scenarios. API 521 treats the scenario as a remote scenario. This paper will provide guidance on methods to mitigate the heat exchanger tube rupture overpressure scenario. The first method is to treat the tube rupture as credible and design the pressure relief system on the low pressure side to handle the tube rupture flow. This can often lead to costly modifications to existing relief valve installations to increase the capacity of the relief system and potentially requires the use of rupture disks. The second method is to perform a Tube Rupture Credibility Assessment (TRCA) which consists of a rigorous analysis of the heat exchanger design to demonstrate that the tube rupture scenario is not credible; thereby eliminated the need to make costly modifications to the relief valve installation.

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