Cautions on the Use of Commercial Aqueous Cleaners in Fluorescent Penetrant Inspection Processes

Liquid penetrant inspection is one of the most widely applied nondestructive inspection processes and thus is a major source of confidence in the structural integrity of engineering systems in our society. The simplicity, broad applicability and low cost of liquid penetrant inspection enables and encourages use by workers with expertise ranging from knowledgeable and skilled, to unknowledgeable and unskilled. Although the results should not be expected to be the same, there is a natural tendency to assume equal capabilities and to assume that variations in the process will not significantly affect results. In many cases, old lessons learned must be relearned and the relearning initiative is often the result of major failure in a structure, component or system. The elimination of ozone depleting hydrocarbons has significantly changed the options for precleaning as the initial step in a penetrant inspection process. This paper is intended to re-identify the role and importance of precleaning in a penetrant process; the impact of changing established precleaning processes; alternate precleaning materials and experiences with alternates; the requirement to optimized and requalify penetrant inspection processes with alternate cleaners; and cautions on the use of silicated cleaners.