Severe leakage on a high percentage of the plug gaskets on a high alloy air cooled heat exchanger during or shortly after initial startup has occurred in only a small percentage of air coolers, but has resulted in costly replacements and unit shutdowns. These problems have occurred with 304L stainless steel (SS), 316L SS and Nickel 200 gaskets, although each material also has many successful applications. The contributing factors to the leakage has included corrosion, galling and/or inadequate manufacturing steps. This paper summarizes a number of case histories and gives their root causes and solutions. The pros and cons of various gasket materials and design options are discussed, along with a proposal for additional requirements to be added to industry standards which would minimize the risks of these problems.
Direct energy deposition processes that utilize wire feedstock have been deployed to deposit and fabricate near net shape functional metal parts at high deposition rates. Is this just multi-pass welding or is there more to it? Should the material requirements for additive be the same as those defined for welding? Is weld quality the same as part quality? A large metal additive part fabricated using a robotic wire arc additive system will be used to demonstrate the similarities and identify critical differences between essential variables for welding and additive manufacturing. The opportunities for both welding and additive manufacturing to learn and leverage one another to develop unique and novel materials, process controls and further fundamental understanding of metal deposition processes will be outlined.