An incinerator recuperator in a chemical plant developed severe leakage due to cracks through the ligaments of the tubesheets. We determined that severe differential thermal expansion between the heavy steel frame, which provided peripheral restraint, and the perforated tube sheet had caused tearing of the numerous tube sheet ligaments.
Analysis confirmed that the initial failure of a single ligament had caused almost instantaneous progression of the failure through rows of ligaments. A design for temporary repair of the failed unit was provided, consisting of inserting and rolling sleeves in the ends of the existing tubes where the tubesheet ligaments had cracked.
These inserted sleeves were then seal welded to the original tubes and a stainless steel pad was applied to the tubesheet to both seal the cracked ligaments and strengthen the tubesheet for temporary operation.
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