1. WELDING INSPECTION AND QUALITY CONTROL
Upon completion of this module you will be able to:
Identify the different inspection methods used in non destructive testing.
The uses and the limitations of the different inspection methods.
Perform Visual Inspection.

2. Introduction.
Inspection, Testing and qualification are growing part of QUALITY CONTROL in manufacturing and maintenance. Quality Control has become very important because of competition and liability. To compete in what has become a global marketplace, companies must produce the best products possible. The cost of inspection and testing of products can save greater expenses later on when the consumer becomes involved. Money that does not have to be spent defending the company can be used for research and development of new products. The WELDER is the person who begins quality control by being satisfied only with Quality Welding.

3. The welder starts the inspection in the process of welding, making immediate adjustment in response to what is being observed in the weld pool. This may require changing the amperage, the travel speed, the arc length or any of the factors that affects quality of the weld bead. Finally, the welder gives the completed weld a final Visual Inspection to look for any defects that could not be seen while welding.

4. Common methods used in NDE
Visual Inspection (VT)
Magnetic Particle Inspection (MT)
Liquid (Dye) Penetrant Inspection (PT)
X-Ray inspection (RT)
Ultrasonic testing (UT)
Air or water pressure testing (LT)

5. VISUAL INSPECTION – VISUAL TEST (VT)
What is Visual Inspection?
NDT process – non destructive testing is the original term used to identify a method of inspection that does not destroy a product usefulness. Current terms include nondestructive inspection (NDI) or nondestructive evaluation or examination (NDE)
Examination with the eye – therefore you are only able to DETECT SURFACE DISCONTINUITIES.
Most important and most extensively used NDE/NDI/NDT method (before any NDT or DT be applied.)
II. Advantages
A. Usually inexpensive - the majority of expense will be in the inspector’s wage.
B. Equipment is small and inexpensive – there’s a lot of equipment to aid in visual inspection, but all small and inexpensive.

6. C. No powered required – this makes VT the most portable NDT process.
D. Can avoid defects and costly repairs – by able to make intermittent inspection
II. DISADVANTAGES
Requires training and experience –the inspector should be familiar with all the welding process.
Must have a good eyes – the AWS requires natural or corrected distance acuity for a certified welding inspector.
May not detect internal defects – limited to surface discontinuities only, but it might give indication of substance indication. Then can be supplemented by some other NDT method.
No permanent records – the inspector must maintain a written log, supplemented by pictures, and tape recorded report.
Subject to human error – must spend adequate time to prevent errors.

7. IV. Five steps of Visual Inspection.
Inspection practice – establish a definite procedure to insure adequate and consistent coverage.
Inspection prior to welding
Inspection during welding
Inspection after welding
Marking and making repairs
V. Equipment required.
Flashlight – used to remove shadows when an extension lamp can’t be used.
Magnifying glass – low power can be used with caution, if allowed by customer or code.
Protective lenses – pocket viewer with proper shade lens to watch the welding taking place.
Weld gage – are hand held measuring devices used to assist during welding and for final inspection.

8. E. Hammer and chisel – to remove spatter or slag from weld prior to inspection. F. Temperature Indicating Devices – some method must be used to determine the preheating, interpass and postheating temperatures. Pyrometer and tempelstick or crayons are commonly used. G. Magnet – a magnet can be used to help determine a material type.

9. Visual Inspection (VT)
Fillet gauges measure
The “Legs”of the weld
Convexity
(weld rounded outward)
Concavity
(weld rounded inward)
Flatness

10. Measuring Steel Rule
Magnifying Glass
Fillet Weld Gauge
Palm Weld Gauge
Micro Caliper
Vernier Caliper

11. VI. Inspection Before Welding
Drawing – drawing are complete and accurate?
Position of welds – does the position called for correspond to the procedure or specification? In vertical is direction of travel correct?
Welding symbols – if they are used are they complete and accurate?
Welding procedure – is the procedure complete and accurate according to the code or specification?

12. E. Material
Did purchasing obtain the correct material such as base metal type and size. The correct electrode type size and the correct shielding gas type and grade.
Materials should be checked for defects. Base metal should be checked rust, mill, scale, laminations or delaminations.
Is the material preparation correct and according to procedure, such as angles and condition after preparation.
F. Assembly
Inspect for proper fit up, as this will prevent discontinuities from occuring.
Jigs and fixtures will assure proper alignment. Make sure they are clean and free spatter and not damaged.
The tack welds are only short welds, but the quality must be the same as all other welds. The tack welds must be made with the same electrodes that are used for the rest of the welds.

13. 4. Pre heat will be used to slow the cooling rate and prevent distortion. The pre heat could be used prior to tacking and / or prior to welding.
G. Equipment
Inspect the equipment for any damaged such as damaged cables, damaged ground clamps, or electrode holders. Inspect the arc voltage and amperage meters making sure they are with in range.
Welder Inspect before welding
- Root Face
- Root Gap
- Bevel Angle
- Joint and Fit up

14. VII. Inspection DURING welding.
Electrodes – inspect for usage of proper electrodes, types, size and storage. Low hydrogen type must be stored in a stabilizing oven.
Root pass – the first layer or root pass is the most important and is particularly susceptible to cracking. Thicker material will crack and will require more pre heat.
Subsequent passes – inspection of successive layers is sometimes carried out with the assistance of workmanship standard. Check for contour or undercut as these are good places for slag to be trapped. Check for proper cleaning between passes as this can prevent slag entrapment.

15. D. Crater formation – make sure crater are filled as this are areas where crack are easily formed.
E. Weld size and sequence – are the weld size according to the print and is the layer and sequence according to the procedure? The use of various gages will determine this.
VIII. Inspection After welding
The applicable code or standard – it will list acceptance standards They will generally cover the following areas;
Weld size – use gages to check conformance to prints
Contour and finish – is the contour convex or concave, and what was called for in print? Is finish smooth and free from surface irregularities.
Cracks – the code or standard will state if any is acceptable and what size.

16. 4. Overlap – it is an indication of lack of fusion 5
4. Overlap – it is an indication of lack of fusion 5. Undercut – if allowed how much? 6. Spatter – what is excessive? IX. Making repairs A. When marking areas to be repaired the marking should be positive and clear. It should be a method that is understood by all involved, should be permanent enough to be evident after the repair has been made and inspected, and the marking must not damaged the part.

17. Non Destructive Testing – Dye Penetrant Test
OBJECTIVE: Upon completion of this module you will be able to: 1. Understand that both Inspection and Testing are necessary for Quality Welding. 2. Identify the different inspection methods used in Non Destructive Testing and Destructive Testing 3. Describe the uses, the process and the limitations of the different non destructive inspection methods. 4. Perform Dye Penetrant Testing.

18. TESTING
Testing becomes necessary for several reasons. If new welding procedures are employed, the manufacturer might be interested in finding out if the welding process is producing quality welds. For example, a product welded by Shielded Metal Arc Welding may be produced more cost-effectively by a Gas Metal Arc Welding process, but will the quality be the same? The manufacturer may be interested in finding out if both the gas metal arc welding process and the filler metals are compatible with the steel used as the base metal. If the steel does not match up with the filler metal, no welding will make any difference.

19. There might also be the question of whether the welders have enough skill at some other welding process to make welds as sound as those made by shielded metal arc welding. No manufacturer wants to risk the company’s reputation with welds that fails to hold up. The least serious outcome might be a product that fails; the worst could be injury or death.
Testing companies provide an invaluable service when it is necessary to have welding examination outside the manufacturer’s plant. Testing companies keep records and furnish the results of weld testing to insurance companies, government agencies and other interested parties. Testing companies provide an important service because, by uncovering problems in welding, they help manufacturers produce safe and durable goods and structures that consumers can live with.

20. TWO METHODS OF TESTING
1. NON DESTRUCTIVE TESTING - leaves the weldment intact, at least until the results uncover major defects in the welding. Consequently, nondestructive testing is often preferred when testing is necessary.
2. DESTRUCTIVE TESTING - results in the destruction of weldment. This is a costly undertaking because of the time and money involved, not to mention the destruction of a weldment that might have to be re-welded.
1. NON-DESTRUCTIVE TESTING METHODS
There are FOUR common methods of Non Destructive Testing:
Magnetic Particle test
Dye penetrant test
Ultrasonic test
Radiographic test

21. Dye Penetrant Test (DPT) and Fluorescent Penetrant Test (FPT) – can locate only cracks and porosity that have formed on the surface of the weld. With the dye penetrant test a highly penetrative liquid is applied to a weld that has been thoroughly cleaned. Upon drying, a developer is applied to the weld. Under normal lighting, any defects are outlined, usually in red, where the dye has been absorbed.
With the fluorescent penetrant test, the weldment is submerged in a fluorescent dye. It is removed from the dye and placed under a black light, where any defects in the weld appear greenish yellow.
Defects Detected
Defects open to surface only – Cracks, slag inclusion, porosity and undercuts.

22. Liquid (Dye) Penetrant Inspection (PT)
Liquid penetrant inspection uses colored or fluorescent dye to check for surface flaws.
PT will not show sub-surface flaws.
PT can be used on both metallic and non metallic surfaces such as ceramic, glass, plastic, and metal.
PT dose not require the part to be Magnetized.

23. Process Principle – 6 steps Surface preparation Penetrant application
Advantages
a. Detects very small, tight surface and subsurface imperfections
b. Simple application and easy to interpret
c. Inexpensive
d. Use in magnetic and non magnetic materials such as ceramic, plastic
Disadvantages
a. Time consuming on various steps of the process
b. Normally no permanent record
EQUIPMENTS FOR PENETRANT TEST
Solvent Cleaner
Penetrant
Developer
Process Principle – 6 steps
Surface preparation
Penetrant application
Excess penetrant removal
Developer application
Inspection / evaluation
Post cleaning

24. DYE PENETRANTS
Types
Red
Flouresant
CAUTION
Oil based
Water washable

25. DYE PENETRANTS Process Principle – 6 steps
1. Surface preparation – remove oil, grease, spatter
1.1. Apply Solvent Cleaner to the area to be inspected
1.2. Use clean rags to remove excess cleaner solvent
2. Apply Penetrant and wait for minutes dwelling time
3. Remove excess penetrant using clean rags
4. Apply Developer and wait minutes dwelling time
5. Inspect and evaluate the red color formation
6. Post cleaning
DYE PENETRANTS

26. DETECTION
Red Dots will appear if Defect is present. Very Red Color the defect is deep and not very red the defect is shallow.

27. II. Application:
Ferrous and non ferrous materials
Plastic and glass – ceramics-insulators-anything that is nonporous
III. Advantages:
Low cost
Ease in application and interpretation – easy to apply and interpret result, discontinuities readily visible and portable.
Less training time for applicator – easy process to learn.
IV. Limitations:
Detects discontinuities that is open to surface only
Can not be used on porous or absorbent materials
V. Safety
a. Ventilation – check for toxic fumes from testing materials. Check for volatility -explosive or fire flash points
b. Fire safety – the test material maybe non flammable but the propellant used with spray cans maybe extremely flammable.

28. b. Fire safety – the test material maybe non flammable but the propellant used with spray cans maybe extremely flammable.
VI. Types:
Fluorescent (type A) – a dye that emits visible light rays when viewed under black light.
1. considered to be more sensitive than the visible type
2. must be viewed under ultraviolet (black light) in darkened overall lighting conditions. More expensive because of equipment required. Limited field use.
B. Visible (type B) – a brilliantly colored dye that is highly visible under normal lighting conditions
1. Use normal lighting for inspection
2. considered to be less expensive.
3. Simplest to use.
4. Easy to use for field work
5. no electric power required

29. Dual sensitivity – works both fluorescent and visible.
VII. Application
Follow Approved Procedure
Clean and dry the surface.
- Solvent cleaner
2. Apply penetrant (brush, spray or dip) penetrant power comes capillary action
3. Penetration time -minimum dwell time is 5-20 minutes
3. Remove excess penetrant.
- when using solvent type, put solvent on a cloth not on the part
- excess penetrant will give false indications
4. Apply developer an allow developer dwell time per standard or specification. A “rule of thumb” developer dwell time is equal to one half penetrant dwell time.
- developer will tend to make discontinuities appear larger.

30. 6. Inspect and examine – true indications are caused by penetrant bleeding from actual discontinuities.
7. Clean if required – same as step 1.
VII. Liquid Penetrant Comparator
Ideal temperature range of the material to be tested is 60 ⁰F –125⁰F. If the test must be done outside of this range, further qualification maybe required.
Test block – to establish acceptability limits of contamination and dilution to see if developer and penetrant are OK.
1. Plated panels – brass panels are plated with nickel and chromium are bent to produce cracks.
2. steel test blocks – annealed type 201 0r 302 stainless steel. Sandblasted on one side only with 100 mesh average size grit, gun held at 18” at 60 psi to achieve velvety finish.

31. 3. aluminum test blocks – type 2024 by heating to 975F and quenched to form cracks. Used to check comparison for operating out of the normal temperature range. Used also to qualify penetrant if shelf is questionable.
Preparation for reuse – blocks should be cleaned with solvent to remove all penetrant from cracks and then heated to dry and also to drive out any remaining solvent.
end

32. OBJECTIVE:. Upon completion of the module, you will be able to; 1
OBJECTIVE: Upon completion of the module, you will be able to;   1. Describe Magnetic Particle Testing and its limitations. 2. Perform Magnetic Test
Magnetic Particle Test (MT) – (commonly referred to as Magnaflux testing)The magnetic particle test begins when Direct Current (DC) electric charges is passed between two poles. The forces line up until there is a break in these magnetic lines of force.
Magnetic particles are applied to the weld in the form of powder. Nothing unusual results when the welding is sound, but when the welding might be defective, a break is created in the lines of force. The magnetic particles become attracted to the defect, which develops north and south poles at the edge of the defect, outlining the defect.

33. Equipment:
1. Iron Particle, wet or dry or flourescent
2. Special power source
3. Ultraviolet light for the flourescent type
DEFECTS DETECTED:
1. Surface and near surface discontinuities
2. Cracks
3. Porosity
4. Slag Inclusions
5. Incomplete Fusion
Advantages
1. Detects discontinuities not visible to the naked eyes
2. Useful in checking edges prior to welding and repairs
3. No size restrictions
Disadvantages
1. Used in magnetic materials only
2. Surface roughness may distort magnetic field
3. Normally no permanent record

34. Magnetic Particle Inspection (MT)
Magnetic Particle Inspection (commonly referred to as Magnaflux testing) is only effective at checking for flaws located at or near the surface.
MT uses a metallic power or liquid along with strong magnetic field probes to locate flaws. (Particles will align along voids)
MT can only be used on materials that can be magnetized. It can not be used be used for nonmagnetic materials such as Austenitic Stainless steel and aluminum.
Principle:
An electric current is allowed to flow in or an electromagnet is applied to part of the specimen to cause magnetic flux to flow in the specimen.

35. If a defect exist in the surface layer, it blocks the flux flow, so the flux flow is directed around the defect while it partially leaks to the air. The leaking flux forms a pair of magnetic poles, S and N, on both sides of the defect.(as shown) SN SN SN SN SN SN SN SN SN SN SN SN N S
Fig. A

36. Since the magnetic poles have larger attractive force than the surrounding material surface, magnetic particles are attracted by and adhere to the magnetic poles while attracting each other. As a result, a magnetic particle pattern wider than the defect is formed on the surface around the defect.
Width of magnetic particle pattern
Width of defect

37. Two methods of magnetizing the weld zone.
To enable the formation of a proper magnetic particle pattern for defect indication, the orientation of the defect and magnetic field must be taken into account.
Two methods of magnetizing the weld zone.
The YOKE method which uses an electromagnet
The PRODE method in which electrode are applied to the specimen to allow current to flow in the specimen.
- not applicable to high tensile steel since it can form a short circuit between specimen and electrodes causing a defect resembling an arc strikes.
- effective to detecting defects not exposed but existing near the surface.

38. Two methods of magnetizing the weld zone.
2. The PRODE method in which electrode are applied to the specimen to allow current to flow in the specimen.
The YOKE method which uses an electromagnet

39. MAGNETIC PARTICLE
Two types of magnetic particles:
Fluorescent type
Non fluorescent type
Methods of particle application:
Wet method – magnetic particles are dispersed by suspension in water or kerosene and the suspension is applied to the specimen surface.
Dry method –magnetic particle are dispersed in the surface of the specimen.

40. Coatings Unfortunately, ASTM E-1444 specifies that Magnetic Particle testing shall not be performed with nonmagnetic coatings (paint, etc.) in place that exceed 0.003" (0.08mm) in thickness, or ferromagnetic coatings (electroplated nickel, etc.) that exceed 0.001" (0.03mm) in thickness. That is not very thick! So be careful on those painted surfaces don't forget the chance of poor bonding on those thin coatings. Current Types ASTM E-1444 recommends: Half-wave rectified AC is best for the dry particle method. For defects open to the surface use AC only. When using Wet particle method for subsurface defects, use full-wave rectified AC.

41. Yokes Funny, but look at the difference, Standards can make on a procedure: ASTM E-1444 requires DC yokes to have a lifting force of at least 30 lbs.(small spacing) and a 50 lbs. lift for a large spacing of legs. ASTM A-275 requires DC yokes have a lifting power of at least 40 lbs at 3 to 6" spacing of legs. The ASME Boiler Code requires a DC yoke to have at least 40 lbs of lift at the maximum pole spacing.
There is a misconception in the 'field' that one can take a yoke and proceed with magnitizing an object by dragging the yoke along the object's surface. Wrong!!!

42. If you are dragging an AC yoke, you are in fact not magnetizing the object but rather you are doing a lovely job of DEMAGNETIZING the object. As in ASTM E-1444 above, paragraph , demagnetizing using a coil (yoke) by moving the object through (which is what you are doing). To correctly magnetize an object, position the yoke and apply magnetizing force for seconds before moving the unit to the next position. So watch which specification and procedure is being applied to your project.

43. Ultrasonic testing (UT)
Ultrasonic testing (UT) is a method of determining the size and location of discontinuities within a component using high frequency sound waves.
Sound waves are sent through a transducer into the material and the shift in time require for their return or echo is plotted.
Ultrasonic waves will not travel through air therefore flaws will alter the echo pattern.

44. ULTRA SONIC
oscilloscope

45. 1.Oscilloscope – to generate and receive ultrasonic waves.
Equipments:
1.Oscilloscope – to generate and receive ultrasonic waves.
2. Cathode Ray Tube – where the traveling distance and intensity of reflected wave are measured to locate and determine the size of the defect.
3.Vibrating Transducer (Probe)
3.1. Straight Beam
3.2. Angle Beam
4.Calibration Blocks – to make time distance and built in holes and notches can be used as amplitude standards.
DEFECTS DETECTED:
1. Can locate all internal flaws located by other methods with the addition of exceptionally small flaws.
ADVANTAGES
1. Extremely sensitive
2. Use restricted only by very complex weldments
3. Can be used on all materials
DISADVANTAGES
1. Demands highly developed interpretation skill

48. Advantages:
Time to inspect – fast response / ability to inspect from one side.
B. Cost - $3, machine / $200.oo transducer
Portable with battery pack
Accuracy can locate small discontinuity
Limitations:
Equipment
Operator
Standards
Reports and records

49. Radiographic Test (RT)
Radiographic Test is a NDT that can detect surface and internal discontinuities using electro magnetic radiation of short duration by means of either
1. X-Ray
2. Gamma Ray
It is a wave of energy that will pass through most materials and develop the negative image of what it passes through on film. Both of these methods are a danger to health
1. An X-Ray- Is electronically produced in a vacuum tube.
2. Gamma Ray-are emitted by the atomic decay.
Two Common Source of Gamma Rays.
Cobalt 60
Iridium 192
3.FILM VIEWER
Pictures taken are viewed as negatives will only give flat image not in three dimensional darkened area must be used for viewing.

51. X- RAY

54. Pictures taken are viewed as negatives
X-RAY VIEWER
Pictures taken are viewed as negatives
will only give flat image not in three dimensional
darkened area must be used for viewing

55. Advantages:
A Radiograph ( X-Ray picture) is a permanent record of a weld used for quality inspection purposes
RT inspections can reveal flaws deep within a component
Limitations:
The necessity to have access to both sides of the part being radiographed
Unfavorable shape and orientation of some discontinuities.
Radiation Safety requirements for personal protection.
Tight Cracks, unless they are essentially normal to the radiation beam.
Shallow tight surface cracks in thick sections usually can not be detected at all, even when properly oriented.
Laminations are nearly impossible to detect because their orientation does not permit sufficient differences in the amount of radiation absorbed through the piece being examined to show the defect on film.

56. Air or water pressure testing (LEAK TEST)
Pressure testing or leak testing can be performed with either gasses or liquids.
Voids that allow gasses or liquids to escape from the component can be classified as gross (large) or fine leaks.
Extremely small gas leaks measured in PPM (parts per million) require a “Mass Spectrometer” to Sniff for tracer gases

57. APPLICATION OF A LOAD Used to test pressure vessels Pipe lines
The item for testing is filled with water or oil it is then pressurised using a pump
A safety valve is set 1.5 to 2 times below the working pressure.

58. PRESSURE TEST
Pressure Gauge
Pump
Test Specimen

60. Quiz time
True or False ?
Dye penetrate inspections can only be used on non magnetic material.
Answer: False

61. Quiz time
True or False ?
X-Rays can only be used to locate flaws at or near the surface of a weld.
Answer: False

62. Quiz time
True or False ?
Virtually all welds have flaws.
Answer: True

63. Quiz time
True or False ?
Magnetic particle testing can only detect flaws at or near the surface.
Answer: True

64. Quiz time
True or False ?
Magnet particle testing can only be done on materials that can be magnetized.
Answer: True

65. Quiz time The letters NDE Mean ___________ ?
A: nondestructive inspection
B: nondestructive evaluation
C: nondisruptive evaluation
D: nondestructive examination

66. Quiz time
The method most often used to check for leaks as small as one part per million (PPM) from a gas line or cylinder is the _________ Method ?
A: hydrostatic
B: mass spectrometer
C: soap suds bubble
D: scleroscope

67. Modern Welding York County School of Technology