[sriram Srinivasan]

Dear all 

  Can I do MPI above painting surface for cs  tank 

Regards, Sriram Srinivasan

[Nambirajan Avudaiappan]

I would like to address a common misconception regarding Magnetic Particle Testing (MPT) on painted surfaces. It's important to note that performing MPT over paint requires a specific procedure demonstration. 

This involves using the same type of paint including DFT range and materials in production grade with test samples containing known defects to do the procedure demonstration.

Furthermore, depending on the asset owner's requirements, this procedure demonstration may need to be witnessed to validate the testing method.

In simple words procedure demonstration required with the same condition of the paint material which to be tested.

Please feel free to reach out if you need further clarification

Regards,

Nambirajan A

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[Deerendra Karanth]

Sir, 

No, you should not perform Magnetic Particle Inspection (MPI) on a painted surface.Paint — even thin — can interfere with this process.Strip the paint from the inspection area (e.g., nozzle welds, seams, etc.)

BR 

Deerendra 

[egwuanimkwu jacob]

Dear all,

No. MPI can only detect defect that is 1 to 2 mm dept. Therefore the paint must have mask the defect.

Thanks.

Egwuanimkwu Jacob 

On Thursday, June 26, 2025 atQa 03:09:52 PM GMT+1, sriram Srinivasan <mail2...@gmail.com>t. 

[kyrillos saad]

ASME section  v 

non standard MPI have a look

[Ramamoorthi Thangarasu]

Mpi for surface and Sub surface Free from defects.
Painted surfaces we can't create magnatic fields, also need test surfaces Free from paint,oil, grease and other foreign materials. No yes for this test ......

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[sridhar cn]

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.

[Nambirajan Avudaiappan]

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

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