Vicoma Identifies the Cause: Analysis of Cracks in an Autoclave

About the Project

The use of clean equipment is essential for our customer in the food industry. An autoclave—essentially a large high-pressure cooker—is used for sterilization. The high temperature and pressure of the steam ensure that everything meets the required standards.
The customer noted that one of the autoclaves might have cracks in the tank wall. To confirm this suspicion, a non-destructive test was performed.

A pink liquid was applied to the suspected cracks on the inside of the tank. This liquid penetrated the wall and left a residue on the outer surface.
After it was determined that cracks were indeed present, the customer asked Vicoma to identify the cause of the problem.

Vicoma’s Role

We set to work to identify the source of the problem. Cracks are caused by localized stresses that exceed the design specifications. This was a perfect example of a situation where the Finite Element Method (FEM)—a method in which Vicoma specializes—proves to be the solution.

Our thorough analysis began with simple calculations to rule out common causes. We then performed more advanced FEM calculations on a 3D model, simulating both the design scenario and the actual situation.
The results of the studies corresponded with what had been observed at the customer’s site: stresses exceeding the design limit were developing at the locations of the cracks.
We were able to trace the problem back to insufficient clearance between the support and the stop block and formulated a recommendation for the ideal clearance.

Result

The customer was very satisfied with the results and our advice. A relatively simple solution with a significant impact: preventing future cracks caused by expansion in this and other autoclaves. The thermal load made this case different from other FEM calculations and thus contributed to expanding Vicoma’s experience with FEM.