Austenitic stainless studs such as B8 and B8M, nickel alloys and non-ferrous parts cannot be magnetised, so magnetic particle inspection will not work on them. Penetrant finds the same kind of surface crack on any of them, but only where the crack is open to the surface: flaws inside need ultrasonic testing. Threads hold dye, so removing the excess there takes care.
ASTM A962, the common-requirements standard behind A193, A194 and A320, has a supplementary requirement for 100% fluorescent penetrant inspection of bolting to ASTM E1417, with set acceptance limits. On austenitic stainless and nickel alloys, penetrant materials with controlled sulfur and halogen content are used.
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model dataThe stud is drawn to scale: a 1 in. UNC double-end stud, 7 in. long, in ASTM A193 B8M. The crack, its width and the film thicknesses are exaggerated so they can be seen. The steps follow the solvent-removable, visible-dye method of ASTM E165; fluorescent inspection of bolting to ASTM E1417 is an ASTM A962 supplementary requirement. Dwell and development times are set by the written procedure, so none is shown.
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