Abstract
Shell and tube heat exchangers are commonplace in many industrial installations. To facilitate cleaning and inspection, exchanger components are made to be unbolted. These custom bolted flanged joints are designed to meet or exceed the applicable code requirements to prevent leakage in service. Plant engineers often inherit “problematic” heat exchanger joints that leak during operation. This may happen during start up, normal operation or during a unit upset condition. Flange re-design is often not an option, and the engineer must analyse the “bad-actor” and seek solutions to prevent future leakage. This paper will explore what makes for a leak free joint based on current industry knowledge and explore tools that can be used to evaluate bolted flanged joints quickly and effectively by the plant engineer. With the publication of WRC 538 and WRC 510, engineers can assess bolted flanged joints based on the limiting design of each component and accurately assess the thermal effects for joints operating at temperature. A step-by-step methodology is provided leading to solutions implemented in two case studies that have resulted in leak free joints between turnaround cycles. These solutions address the root cause of all flange leaks which is insufficient gasket stress. However, loss of gasket stress may result for a variety of reasons which are explored in detail.
