Checks (3)

Question 1

Ammeter Accuracy / Current Output Checks

Answer 1

Equipment ammeter readings are compared to a control test ammeter.

• a shunt (current transformer) monitors the amount of current output provided by the unit when affixed between the units contact plates through the entire “tap” switch or amperage range.
• 6 month intervals
• accurate within +/- 10% (+/- 5% on multidirectional) true value
• plotted on graph (tap setting vs amp values. lines for both test and unit ammeter)

Question 2

Timer Control Checks

Answer 2

Done with a suitable electronic timer

• 6 month intervals
• current flow / magnetizing shots should be in 1-2 second bursts
• accurate within +/- 0.1 seconds

Question 3

Quick Break Checks

Answer 3

“quick break” refers to the sudden stopping or ending of magnetizing current, in longitudinal magnetization a quick break can induce eddy currents, causing strong bar end polarity making inspection difficult.

• quantified by how quickly the magnetic field collapses
• oscilloscope
• 6 month intervals

Question 4

Internal Short Circuit Checks

Answer 4

Setting amperage to maximum setting and activating current with nothing clamped (no conductor).

• any measured amperage on ammeter indicates an internal short circuit - discontinue equipment use
• check periodically or by manufacturer recommendation

Question 5

Black Light Intensity Check

Answer 5

Verify performance using a calibrated UV intensity meter.

• recommended to check before each use
• ASTM E709 check at intervals not exceeding 1 week and/or every time the bulb is changed
• battery powered lamps must be checked before each use
• 300 to 390nm
• minimum 1000μW/cm²
• ASTM E709 distance during intensity check should be 38cm (15in)

Question 6

Other Black Light Check Information

Answer 6

• filters checked weekly (max filtering of visible light and harmful UV rays)
• Mercury Vapour Arc Lamps warm up times: some are 2-3min, most 5-15min
• some LED UV-A need warm up minimum of 5min
• intensity checks in darkened area
• adaption time 3 minutes
• maximum visible light should be = or <21.5 lux (2ft candles)

Question 7

Visible (White) Light Intensity Checks

Answer 7

Visible light intensity should be:

• > 1076lux (100ft candles) at exam surface
• > 538lux for field inspections with non-fluorescent particles
• fluorescent inspections in darkened areas no >21.5lux (2ft candles)
• performed on weekly

(ASTM E709)

Question 8

Stationary Unit Particle Concentration Check

Answer 8

• Visible bath: 1.2 - 2.4ml/100ml vehicle (optimum: 1.5 - 2.0ml/100ml)
• Fluorescent bath: 0.1 - 0.4ml/100ml vehicle (optimum: 0.15 - 0.20ml/100ml)

Question 9

Particle additive methods:

Answer 9

• Dry powder (measured)
• Paste (weighed)

both are poured into bath with agitation system running, drawn into pump and dispersed, settling test performed after 10 minutes.

Question 10

Suspension bath changes from use:

Answer 10

• drag out of particles
• drag out of liquid
• evaporation
• accumulation of contaminants
• objects dropped in tank
• dilution from wet test pieces

Question 11

Agitation time required when system has been off

Answer 11

• off for >4 hours, 30min agitation time
• off for 30-60min = 10min agitation time
• off for >1 week, 60min agitation + stirring

Question 12

When the contamination exceeds ___% of the volume of the particle layer, formation of proper indications will be _impeded, and the bath must be discarded.

Answer 12

30%

• as often as 1 week when unit is in constant use

Question 13

Water Break Check

Answer 13

Ensure suspension provides necessary wetting characteristics, particle dispersion and corrosion protection.

• Conditioned Water vehicles: wet a specimen and observe suspensions appearance on part surface, if it breaks exposing the parts surface or forms droplets, more wetting agent is necessary.
• pH Test of conditioned water vehicles: verified using a pH meter or pH paper

Question 14

Types of System Performance Checks

Answer 14

• production verification on parts with discontinuities
• fabricated test parts with discontinuities
• test plates
• test ring specimens (ketos ring)

Question 15

Performance Check - production verification on parts with discontinuities

Answer 15

particle and equipment performance

- discontinuities of known shape, size and placement

Question 16

Performance Check -fabricated test parts with discontinuities

Answer 16

system, particle and sensitivity performance

- defects of varying severity levels

Question 17

Performance Check -test plates

Answer 17

check wet and dry techniques for prod or yoke methods

- artificially induced flaws via heating and cooling and/or EDM notches

Question 18

Performance Check - test ring specimens (ketos ring)

Answer 18

verify system performance - wet, dry, fluorescent and non-fluorescent techniques and verify maximum depth of subsurface discontinues that may be detected.

• stationary unit central conductor
• series of 10-12 1.78mm (0.07”) diameter side drilled holes set a various distances from outside surface, 1.78mm (0.07”) to 21.3mm (0.84”)

Question 19

Lift Test (hand held yokes or permanent magnets)

Answer 19

AC electromagnets/yokes and permanent magnets
- 10lbs @ 2-4in spacing

DC - electromagnets/yokes

• 30lbs @ 2-4in spacing
• 50lbs @ 4-6in spacing

Question 20

Performance Checks for Magnetic Field Indicators

Answer 20

• full wave DC current checked at regular intervals
• half-wave and AC compared with results indicated by QQI’s (AS 5371)
• 6 month intervals