Developement Of Eddy Current Inspection

Front 1

What are the three eddy current techniques?

Back 1

1. Thickness technique
2. corrosion detection
3. conductivity measurement procedures

Front 2

What technique is used to detect corrosion on the far side of a specimen as well as thickness of thin sheet metal?

Back 2

Thickness technique

Front 3

All thickness measuring should be performed in accordance with what?

Back 3

Per- establish procedures

Front 4

What must be establish that will limit or restrict thickness measurement?

Back 4

the presence of geometrical factors

Front 5

to perform thickness measurements what is the objective?

Back 5

is to select the a frequency low enough to penetrate all the way through the part

Front 6

What field strength gives reasonable sensitivity to thinning

Back 6

On standard depth of 36.8% of the field

Front 7

only when can you measure thickness changes?

Back 7

on material less than one standard depth in thickness

Front 8

Test system requirements for corrosion detection depends on what?

Back 8

Type and depth of corrosion

Front 9

Thickness measuring systems provide optimum detectability for what corrosion types?

Back 9

uniform etch corrosion and large pits

Front 10

For small pits and small areas of exfoliation or inter-granular attack, inspection requirements become similar to what?

Back 10

sub surface flaw detection

Front 11

In conductive measurement, most applications specify a particular instrument; in most cases what type of meter may be used?

Back 11

any approved conductivity meter

Front 12

When prepare a part ans as with all eddy current inspections the area must be free of what?

Back 12

sharp slivers and foreign material which could damage the probe

Front 13

Calibration requires two standards of known conductivity and the conductivity of the inspection part should fall where?

Back 13

within the range of the two standards

Front 14

For best sensitivity to conductivity changes pick a frequency that puts the nominal conductivity where?

Back 14

near the vertical part of the conductivity curve

Front 15

what will make thickness changes to cause inaccurate conductivity readings?

Back 15

if the frequency is chosen to be so low that the part is completely penetrated

Front 16

Do not attempt to take conductivity readings on material thinner than what?

Back 16

three standard depths of penetration

Front 17

What is acceptance/rejection criteria?

Back 17

for many alloys it can be specified by conformance to a particular range of conductivity values