3-9. Selection of Inspection Process. The selection of a suitable penetrant inspection process is dependent on seven
basic factors These are as follows:
Requirements previously established by component drawings or applicable documents on material or parts to
be placed under test.
Penetrant sensitivity required.
Surface condition of part to be tested.
Configuration of part to be tested.
The number of parts to be tested
Testing facilities and equipment available.
Effect of the penetrant chemicals on material or system being tested
3-10. Pretesting, Precleaning, Drying, Application, and Removal. The following paragraphs describe pretesting,
precleaning, drying, application, and removal These are used for the preparation of parts prior to, during, and after
Pretesting. The purpose of pretesting is to ensure that the parts to be tested will not be damaged by the
inspection or preparation process described in this section, to establish emulsifier dwell times (if applicable), and to
provide a reference sample The following procedures are used for pretesting
Select the penetrant Inspection process to be used on all parts.
Select a part identical to the parts to be placed under test.
Perform penetrant inspection on the part selected In step 2 in the same manner In which all parts will be
Concurrently with step 3 and after each inspection process procedure, check the part for damage or
This procedure will, in effect, provide a reference sample, for other identical parts to be tested.
If damage occurs, or adverse effects are noted, select an inspection process which will eliminate the
Precleaning. The purpose of precleaning a part is to remove all foreign matter which will prevent detection of
defects or confuse or alter defect indications Cleaning shall be accomplished in accordance with TM 55-1500-335-23.
Detection and indication of any defect depends upon the flow of the dye penetrant into what may
be only a microscopic crack It is apparent that such flow cannot take place if the crack is already
filled with carbon, oil, engine varnish, dirt, water, paint, oxide, plating, or similar coatings that
may cover or fill the defect. Therefore, unless the part is clean and free from foreign matter that
may cover or confuse the indications, reliable inspection may not be accomplished.
Drying. The purpose of the drying process is twofold. After cleaning or rinsing, the drying process is used to
assure the evaporation of any water, solvents, or cleaning solutions which might be loaded in a crack or defect. After the
application of wet developer, the drying process is critical and is used to secure a uniform developer coating. It may also
assist in the development of the flaw indication.
Penetrant Application. Type I and II penetrants can be applied by one of the following methods
Any other method which completely covers the area of Inspection.