Page 20.12 Chapter 20 Standard Practices MAY 2015
20-40 Non-Destructive Testing
WARNING
Refer to appropriate Material Safety Data Sheet (MSDS) and
take necessary safety precautions when working in proximity to
hazardous materials.
20-41 Magnetic Particle Inspection
Ferromagnetic steel parts must be inspected for structural defects using magnetic particle
inspection.
Steel parts covered by this specification shall be inspected per ASTM E 1444 wet process
with ultra-violet light. Applicable requirements and limitations of the above standard shall
apply. Parts shall be thoroughly demagnetized and cleaned after inspections. Record the
size and location of all rejectable indications.
Procedures and equipment used to perform the inspection shall conform to requirements
of ASTM E 1444. Whenever possible, parts shall be inspected with both circular and
longitudinal magnetization.
A. Inspection Criteria
Parts (except gears) which are inspected by magnetic particle inspection shall be
accepted or rejected according to the following criteria:
Acceptable indications:
y Indications smaller than 0.015 inch are not considered ratable.
y Indications caused by sharp changes in cross-section or part geometry.
Rejectable indications:
y Indications interpreted as cracks, seams, laps, shuts, or any flaws which are open
to the surface.
y Indications oriented at an angle of more than 15 degrees from the longitudinal axis
with length exceeding 0.125 inch.
y Circumferential indications on any shoulder or fillet (changes in diameter).
y Any indications which break over an edge, shoulder, fillet radius, keyway, spline, or
an adjacent area of part more than 0.015 inch.
y Indications caused by undercuts at the toe of a weld.
y Indications caused by cracks in the weld or parent metal.
y Indications caused by inclusions in weld material exceeding 0.1 inch in length.
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