Eddy Current Tube Standard MFL by Nde Flaw Technologies Private Limited

Application

Description

MFL

Comments

Heat Exchangers

Mildly ferromagnetic material Duplex steel, SS439, Secure, Monel

X

– ECT is used only for thin tubes (<1.6 mm) with saturation probes.- For thicker walls, it is better to use RFT or MFL.- IRIS can sometimes be used to confirm the sizing of defects.

Ferromagnetic material Carbon steel, nickel. Typical defects are pitting and corrosion.

X

– RFT, MFL, and IRIS are good, and most of the time complementary.

Air Coolers

Carbon steel tube with aluminum fins Typical defects are ID pitting and OD wear close to the water box.

X

– RFT is not effective because the fins disturb the remote field.- MFL is quick and sensitive but does not allow sizing.- IRIS is often used to back up MFL but has difficulty with OD flaws.

Boilers

Carbon steel tube Typical defects are pitting, wear, and cracking at the tube sheet.

X

– RFT is good for wear detection and can easily pass the bend.- MFL is good only on straight boiler tubes without swages.- IRIS is good for wear and pits but has no sensitivity in the bend.