Understanding and Preventing Failure of Aluminum Equipment in the Presence of Liquid Mercury

摘要

Liquid Hg in contact with aluminum is a concern for Ethylene gas processing plants that utilize Brazed Aluminum Heat Exchangers and other aluminum equipment. The concern is the potential for failure during operation and risk analysis for continuing operation once Hg is detected. The mechanism for failure for aluminum components, primarily aluminum welds, is reviewed as well as an explanation of key terminology. This mechanism identifies the weld metal as the primary site of failure initiation as found during the analysis of field failures. Understanding how and why failure occurs is key to knowing where and how to prevent failure. This paper will present a simple test to determine if weld metal (or sensitized base metal) will be susceptible to Hg LME failure. This test can then also be used to develop weld methodology that can be used to prevent aluminum components from susceptibility to Hg attack. Understanding the primary cause of failure can be used to develop robust weld processes that are resistant to Hg attack and to provide understanding in how to assess risk analysis for those plants which have or may have Hg present in Brazed Aluminum Heat Exchangers or other aluminum equipment.