Drying: Drying takes 5-10 minutes depending on air temperature, it can be assisted
by using lint free cloth and the application of compressed air.
Application of developer: Shake the spray can for 2 minutes then spray a thin even
coat of developer (Section 4 Table 4-1, Item 16) from a distance of 9 in (228 mm). Avoid
thick coats and pools of wet developer which may mask the indications.
Inspection: Examination of surface should begin as soon as developer is dry and
should be repeated periodically up to 15 minutes from application. The level of illumination
in the area of inspection should not be less than 500 lux.
Linear indications such as surface breaking, lack of fusion and cracks - not
Porosity or blow holes in excess of 0.059 in dia. (1.5 mm) - not acceptable.
Porosity in excess of 1% by area - not acceptable. Refer to porosity charts,
Imperfections found in forging material shall be reported to the inspection
authority for further investigation.
Recording: A record of all work carried out shall be logged in a record book. This
shall include unique component identity (serial number), date of test, verdict and details of
corrective action taken if required.
TABLE 3-1 POROSITY TABLE
The number of gas pores allowed in a 2 in (50 mm) length of weld for different weld widths for 1%
by area is as follows:
Examples of 1% porosity levels (fig. 3-7) in 0.40 in (10 mm) and 1 in (25 mm) wide welds are as
Appendix K Page 17