Question

NDT Liquid Penetrante Testing

What control measures should be considered in developer thickness layer?

Answer 1

in a penetrant inspection function of developer is very important.

(1) It must draw out of the discontinuity a sufficient amount of penetrant to form an indication, and it must spread the penetrant out on the surface to produce a visible indication.

(2)In a fluorescent penetrant inspection, the amount of penetrant brought to the surface must exceed the dye's thin film threshold of fluorescence, otherwise the indication will not fluoresce and also the developer makes fluorescent indications appear brighter than indications produced with the same amount of dye but without the developer.

(c)for accomplishing these functions, a developer should stick to the part surface and result in a uniform, highly porous layer with many paths for the penetrant to be moved due to capillary action.

(d)Developers can either beapplied wet or dry, but the desired end result is always a uniform, highly porous, surface layer. the quality control requirements for each of the developerlayer types might be is slightly different, they will be covered individually.