Identifying Metal with Eddy Current Using the ED250

General

1. This inspection is accurate for the following:
   1. Being able to separate or identify stainless steel Gr 316 from Gr 316L or dual certified.
   2. Being able to separate or identify SA517 Gr 70 from SA36
   3. Being able to separate or identify any alloy designation UNS number from another alloy designation UNS number.
2. The following essential variables must be considered for an accurate inspection:
   1. There must be a "STANDARD" of the alloy that needs to be identified and the STANDARD must be at least 0.375" thick and have a defect free surface area of at least    1.0 square inch with a surface finish of at least 32 micro inches or smoother.
   2. The STANDARD's surface must be the same as the piece to be identified. i.e. flat or a radii of 1.75" etc.
   3. The temperature of the STANDARD and the piece to be identified must be within 10 degrees Fahrenheit of each other
   4. The angle of the probe must be held at the same on both the STANDARD and the piece to be identified.
   5. The amount of pressure holding the probe to the surface of the STANDARD or the piece to be identified must be about the same.
   6. The piece to be identified must not have been subjected to any form of heat treating prior to identification.

Instructions

1. Balance ED520 on the piece to be identified
   1. Plug in ED520 if external power is available
   2. Turn "ON/OFF" knob to "TEST" position and insure that the needle reads at least "390" (at the red mark)
   3. Plug in probe to ED520
   4. Turn "ON/OFF" knob to "LO" position
   5. Turn "SENSITIVITY" knob to about the center
   6. Insert probe into "stabilizing block" so the tip of the probe is level with the edge of the block (not coming through)
   7. Place probe on piece at least 0.5" away from the edge or any defects
   8. With the probe held steady on the surface of the piece, adjust the "BALANCE" knob so the needle is centered at 250 +/- 20
   9. Hold probe in air at least 6.0" away from anything, and adjust the "LIFT-OFF/FREQUENCY" knob so the needle is centered at 250 +/-20
   10. Repeat steps H and I, in order until the needle remains at 250 +/-20 whether the probe is in the BALANCE or LIFT-OFF position or not.
2. Compare the indication received from the piece to the indication received from the STANDARD
   1. With the ED520 balanced on the piece, move the probe to a surface on the STANDARD at least 0.5" away from the edge
   2. Repeat step A to each possible STANDARD until you receive the same indication from the piece and the STANDARD +/- 150. This will indicate what alloy the piece is.

Liquid Dynamics International

Issue No.: 3
Amendment No.: 0
Date: July 29, 1996
Approved: MRP
 

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