(Refer: Mandatory Appendix 8 (Page 417) of ASME BPVC Section VIII Div 1, 2017 Edition.)
The following terminologies have been used to explain the acceptance/rejection criteria for Liquid Penetrant Examination (PT).
Relevant Indications: Indications with major dimensions greater than 1.5 mm (1/16 in.) shall be considered relevant.
Linear Indication: Any indication with a length greater than three times the width.
Rounded Indication: Any indication with a length equal to or less than three times the width. A rounded indication may be of circular or elliptical shape.
Acceptance Criteria for Liquid Penetrant Examination (Mandatory Appendix 8):
All surfaces to be examined shall be free of:
(a) Relevant linear indications shall be rejected.
(b) Relevant rounded indications greater than 5 mm (3/16 in.) shall be rejected.
(c) Four or more relevant rounded indications in a line separated by 1.5 mm (1/16 in.) or less (edge to edge).
Please watch the video (given below) for more clarity on acceptance criteria for the Liquid Penetrant Test (LPT);