Re: [MW:35702]

Dear Mr sridhar,

Now a days code not allowed this.

Because the magentization depend upon the material permeability and type of coating we will not able to finalize the range of magentic permablity to detect the discontiuity so the procedure demonstration is required in painted surface MPI.

You can refer to ASME sec V art 7 mandatory appendix 1 I-741 COATING THICKNESS MEASUREMENT can described about the procedure demonstration.

Best regards,

Nambirajan A

NDT level III

On Fri, 27 Jun 2025 at 08:56, sridhar cn <sridharcn305@gmail.com> wrote:

MPI can be conducted on painted surfaces if the paint thickness is within acceptable limits, typically less than 0.05 mm 

(1 to 2 mils) for non-fluorescent particles and up to 0.1 mm for fluorescent particles. Thicker coatings may reduce the 

sensitivity of the inspection by weakening the magnetic field or obscuring indications.

The ability to detect subsurface defects may be compromised if the paint is too thick or if the magnetic field strength is 

insufficient. Adjust the magnetising current and equipment (e.g., yokes, prods, or coils) to account for the coating.

Consider removing the paint in the inspection area. Alternatively, use other non-destructive testing methods like ultrasonic 

testing (UT) for thicker coatings. Always validate the MPI procedure on a painted test piece with known defects to confirm 

sensitivity.  

C Sridhar.

On Thu, 26 Jun 2025 at 19:39, sriram Srinivasan <mail2ram40@gmail.com> wrote:

Dear all 

  Can I do MPI above painting surface for cs  tank 

Regards, Sriram Srinivasan

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