FST 2002 – Welding &NDT No. 1

CONTENT PART 1

• Overview Test Methods

• Basis of test methods

• Execution of examinations

• Detectable type of faults

• Limits of application

FST 2002 – Welding &NDT No. 2

CONTENT PART 2

• Planning of NDT

• Content of test procedures

• Evaluation of results

• Recording of tests and results

• Applicable NDT Rules

FST 2002 – Welding &NDT No. 3

Magnetic Particle Testing (MT)

• Principle:

• Materials must be ferromagnetic• Stray flux of a magnetic field generates lines of

force, which emerge from the surface when passing a discontinuity

• Discontinuities will be visible by accumulation of ferromagnetic particles

FST 2002 – Welding &NDT No. 4

Generation of a Flux Indication

FST 2002 – Welding &NDT No. 5

Test Methods

FST 2002 – Welding &NDT No. 6

Contrast

Test Test surface and mag. particles together should provide high contrast.Appropriate particle colours should be chosen, e.g. black, red, grey.

With fluorescent particles, max. fluorescence brightness should be selected.

Remark: Thin surface coating (background paint “white”) together with black mag. Particles provide very good contrast.

poor contrastStrong background disturbance

FST 2002 – Welding &NDT No. 7

Distribution of Field Lines in the Material

FST 2002 – Welding &NDT No. 8

Magnetic Field Types

•Alternating Current:•Penetration depth 2-3 mm from surface•Small influence of surface shape•Required magnetic force is smaller (lower weight of equipment

•Scope of application:•Welds, gear-tooth

FST 2002 – Welding &NDT No. 9

Magnetic Field Types

•Direct current:•Deeper penetration•Insufficient magnetisation at

cross section changes, edges•Scope of application:

•Stationary equipment

FST 2002 – Welding &NDT No. 10

Depth Penetration of Magnetic Fields

Surface flaw Subsurface flaws

A.C magnetic field skin-effect, penetration small. Flaw depth max. 2-3 mm with f=50 hZ

D.C Magnetic field entire cross section magnetized, greater depth penetration. Flaw depth max.5-8 mm

FST 2002 – Welding &NDT No. 11

Standard Magnetic Particle TestingYoke Magnetization

FST 2002 – Welding &NDT No. 12

Yoke Magnetisation

a: Soft iron coreb: Magnetic field linesc: Magnetic coild: Flux indicatione: Stray fluxf: Defect

FST 2002 – Welding &NDT No. 13

Magnetisation Direction

FST 2002 – Welding &NDT No. 14

Standard Equipment

FST 2002 – Welding &NDT No. 15

Application of Cross Yoke Magnet

MT of a circumferential weld.

FST 2002 – Welding &NDT No. 16

Right – Hand - Rule

I = CurrentH = Magnetic Field Strength

(magnetic field lines)B = Magnetic Induction

The right hand rule define the relation between curent, magnetic induction and the direction of the magnetic field lines.

FST 2002 – Welding &NDT No. 17

Direct Fluxing

FST 2002 – Welding &NDT No. 18

Application of Direct Fluxing

Magnetisation by prods

FST 2002 – Welding &NDT No. 19

Application of Direct Fluxing

FST 2002 – Welding &NDT No. 20

Coil Magnetisation

FST 2002 – Welding &NDT No. 21

Application of Coil Magnetisation

FST 2002 – Welding &NDT No. 22

Threading Bar Technique

FST 2002 – Welding &NDT No. 23

Induction Fluxing

FST 2002 – Welding &NDT No. 24

Testing Accessories

• Indication capability of the testing fluid• Defect recognition• Suspension evaluation• After a setting time of 30 minutes the required concentration must be obtained.

FST 2002 – Welding &NDT No. 25

Test Block MTUC – No.3

• To check magnetic powder suspensions for theirefficiency

• Regular control

FST 2002 – Welding &NDT No. 26

Berthold Test Block

• For determination of the field direction• Minimum angle between field – and crack

direction 30o

FST 2002 – Welding &NDT No. 27

Field Strength Meter

• Determination of field strength• 20 to 65 A/cm or (2,0 to 6,5 kA/m)• Control of demagnetisation• Maximum allowable residual

field intensity• Max. 4A/cm (0,4 kA/m)

FST 2002 – Welding &NDT No. 28

Light Intensity Meter

UV Intensity Meter Luxmeter

FST 2002 – Welding &NDT No. 29

Detectable Flaw Sizes

FST 2002 – Welding &NDT No. 30

Defects IndicationSurface flaws Subsurface defects

FST 2002 – Welding &NDT No. 31

Irrelevant IndicationsDevelopment of stray-flux with strong magnetization

Cross-section changes, edges Irrelevant Indications

FST 2002 – Welding &NDT No. 32

Local Permeability Change

MT of 2,5% Ni-Steel, austenitic welded, rechecked by PT

FST 2002 – Welding &NDT No. 33

Evaluation of Discontinuities

Form of indication (linear,round)Size of indicationsQuantity of indicationsLocation, direction andOrientation of indications

FST 2002 – Welding &NDT No. 34

Magnetic Particle Standards

• Standards for performance of tests:• DIN EN 1290 “Magnetic Particle Examination of Welds”• ASME Sec. V, Subsection A, Article 7 “Magnetic Particle

Examination”• ASME E-709 “Standard Recommended Practice for

Magnetic Particle Examination”• DGZfP Richtline EMO “Performance of magnetic particle

examinations” (EN ISO 9934-1)

FST 2002 – Welding &NDT No. 35

Evaluation Standards

• AD-Merkblatt HP 5/3 Anlage 1 “Non Destructive testing of welded connections” (Pressure vessels)

• DIN-EN 1291 “Magnetic Particle Examination of Welds –Evaluation Criteria”

• Germanischer Lloyd II/3 Chapter 2 Sec.4 “Non Destructivetesting of welds”

FST 2002 – Welding &NDT No. 36

Acceptance Criteria

FST 2002 – Welding &NDT No. 37

Imperfections in Welded Joints in Steel according to EN 25817

FST 2002 – Welding &NDT No. 38

Recording of MT

• Details of test object:• Marking of test object• Material• Dimension• Welding proces• Area tp be tested• Specification

• Details of examination:

• Surface condition

• Type of magnetisation

• Tangential field strength

• Magnetic powder

• View conditions

• Demagnetisation