1100 gorman rt-ut presentation for ctms oct 07

8/4/2019 1100 Gorman RT-UT Presentation for CTMS Oct 07

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Alternat ives to RadiographicWeld Inspection

October 2007

Puget Sound Naval Shipyard & IMF


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Radiographic Testing

Definition:

Radiography is a method fornondestructive inspection ofcomponents and assemblies that is

based on differential absorption ofpenetrating radiation by the partbeing inspected.


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Radiography

Top view of developed film

X-ray film

The part is placed between the

radiation source and a piece of film.

The part will stop some of theradiation. Thicker and more dense

sections stop more of the radiation.

= more exposure

= less exposure

The film darkness(density) will vary with

the amount of radiation

reaching the filmthrough the test object.


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Radiographic Images


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Advantages:

a) Volumetric inspection. Magnetic Particle and Liquid Penetrant are forsurface inspections even when applied to eachlayer.

b) Can be used on a variety ofmaterials.

c) Film provides a permanent record.

d) Gamma radiography does notrequire electrical power.


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Radiographic Testing PSNS Applications:

a) Piping Welds. b) Structural Welds.

c) Castings. d) Various components for internal

structure (info).


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Detectable Flaws:

a) Slag. b) Porosity.

c) Cracks. d) Inclusions.

e) ID Root Conditions (contour

and oxidation)


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Structural


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Piping


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Slag


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Porosity


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Casting Cracks and Inclusions


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Butt Weld RTPipe Size and Material

Pipe sizes (IPS)

Range - in to 20 Inches Material

Carbon Steel 2-1/2 to 16 inches CuNi (70:30 & 90:10) Mostly 2 to

5 inch

NiCu (Monel) Mostly 2 to 5 inch

Grade 300 Series CRES - 4 inch and

less Inconnel 4 inch and less


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Field Radiography

In the field and

shipboard, structures

are radiographed using

radioactive sources


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Radiography Challenges

Limitations:

Safety considerations lead to: Large, expensive crews needed to guardRT areas.

Limited (1 or 2) joints inspected per shift.

Disruption of other work.

Potential safety hazard.

Certain types of flaws are difficult

to detect. Film interpretation requires skill.


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Further Limitations:

Crew size is approximately 15people; can be as many as 30 onaircraft carriers.

Training personnel: 80 hours initialtraining; 24 hours of trainingannually to maintain proficiency.

Cost/Schedule impact on projects.


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Global Pacific Operations

Designing/installing shielding toreduce crew size is costly.

Exposure devices are shielded with

depleted uranium; some foreigncountries do not allow the exposuredevices on their soil.

Shipping expenses involved withperforming RT in other countries.

Access to spaces by foreign

nationals.


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Could crew sizes be smaller?

Could exposure devices be shieldedwith a different material?

Could X-ray machines be more

portable to facilitate performing x-rayshipboard? (i.e., source-film distance

difficult to maintain with shipboardinterferences, weight of machine ~400lbs.)

What digital equipment is available?


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Ultrasonic Testing

Definition:

Ultrasonic inspection introducesbeams of high frequency soundinto the piece. The sound reflected

at material interfaces is analyzed todefine the presence and location ofdiscontinuities.


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High frequency sound waves are introduced into a material andthey are reflected back from surfaces or flaws.

Reflected sound energy is displayed versus time, and theinspector can visualize a cross section of the specimen showingthe depth of features that reflect sound.

f

Oscilloscope, or flaw

detector screen

plate

crack

0 2 4 6 8 10

initialpulse

crack

echo

back surfaceecho

Ultrasonic Inspection


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Ultrasonic Testing

Uses:

Detect internal flaws Bonding of materials

Measure material thickness.


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Ultrasonic Testing

Advantages.

Deep penetration, for thickmaterials.

Detects extremely small flaws.

Only one surface needs to beaccessible.

Volumetric scanning Portable.


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UT

PSNS Applications: Thickness gauging.

Pipe/tank liquid level. Silver Braze joint bond. Welds for discontinuities.

Detectable Flaws: Cracks.Voids. Porosity. Laminations.

Unbond in materials. Thickness variations.


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Ultrasonic Testing

Limitations:

Requires experienced technicians. Rough, irregular or thin parts are

difficult to test.

Surface flaws may not bedetectable.

Requires direct coupling. Reference standards are required.


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Ultrasonic Inspection

Angle beam ultrasonic

flaw detection is used

to inspect welds using

the shear wave mode

of transmission to

detect welding

discontinuities such as

lack of fusion and slag

inclusions.


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Ultrasonic Challenges

A-scan must be recordable.

Samples with known defects arerequired to prove new processes. Root convexity, oxidation, porosity.

Surface/ID detection ofdiscontinuities.

False positives (too sensitive). Joint configuration (fittings, elbows,

wall thicknesses).


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Ultrasonic Specifications

Military Specifications 1688,

1689, 2035A, TP-278 are similarto ASME, API, and ABS.

Current acceptance criteria is forstructural welds not piping welds.


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Points of Contact

Engineering Ole Hovland

360.476.7418 Dennis Yeats

360.476.8744

Radiography (RT)

Primary - Richard Franklin360.476.2990

Secondary - Christina Klinkert360.476.3321

Ultrasonic (UT) Primary - William Robbins

360.476.2990 Secondary - Nona Brown

360.476.3321

1100 gorman rt-ut presentation for ctms oct 07

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