MFL Field Verification with UT C-Scan.

[Adib CJ]

Dear fellow engineers,

So we need to verify anomalies from MFL inspection with UT C-scan on a pipeline.
The model for UT C-scan we used is Olympus Omniscan MX 2. Probe size A12 and scanner speed is 60mm/s.

The range of the MFL anomalies (internal corrosion), approximately a dozen of them are within 10-330mm in width, 19-146mm in length across the pipe, and peak depth of 16-48%.

However, UT C-Scan only get 17% loss at the expected area

My questions are:
1. Any possible limitations on the UT C-scan?
2. Any suggestions to verify the findings? It is believed that C-scan is the best method available to verify internal corrosion.

Thank you.

 

[SJones]

Both inspection methods will have a reliability profile. Decision making with respect to results needs to incorporate the knowledge of those reliability profiles. The method selection process should have documented these profiles.

Have a look at NACE Corrosion 2014, Paper 4139 and

http://nugenia.org/wp-content/uploads/2019/03/ENIQ_61_methodology_issue_4_final.pdf

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[Dhurjati Sen]

Dear Adib CJ,

What's better than to cut the pipes and satisfy thy eyes?

Regards.

DHURJATI SEN
Kolkata, India

 

[MATEGRITY2009]

As you already knew MFL is a Screening tool and it has a lot of limitations eg. pipeline cleanliness, a sensor to wall distance, magnetic interference etc. which can make the data deviation. if all UT parameters are set correctly, it will give you a more accurate result better than the MFL result.