Abstract
Construction of a Plant was nearing completion when it was discovered that galvanized carbon steel scaffolding had been used during the installation of the refractory in the cracking furnaces. Zinc transferred by contact from the scaffold onto the furnace tubes was identified during the construction phase.
This was concerning because contamination of the superalloy furnace radiant catalyst tubes with residual zinc could potentially lead to liquid metal embrittlement (LME) when the tubes are heated to the furnace operating temperature. An analytical method (Dithizone reagent [CAS 60-10-6] used as a complexant in a colorimetric method) typically used in laboratories was scaled to an industrial construction environment to inspect for the presence of zinc. The robustness of the method was first tested in the laboratory and demonstrated in field trials. A handheld X-Ray Fluorescence device was used in conjunction with the colorimetric method to identify the presence of zinc and confirm its removal. This paper describes the scaling process used and the logistical challenges associated with inspecting extensive lengths of tubing for potential contamination.
