Transcript NozzleInspect

NDT Technology Group
TWI Ltd
Best Practice
Conduct of NDT
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www.twi.co.uk
What is NDT?
A method of determining …
• the integrity of a material,
component or structure
• or the characteristic of an object
… without rendering it unfit for further
use!
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Conventional NDT methods
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Ultrasonic Testing (UT)
Magnetic Particle Inspection/Testing (MPI/MT)
Penetrant Testing (PT)
Eddy Current Testing (ET)
Radiographic Testing (RT)
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Advanced NDT methods
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Time of Flight Diffraction (TOFD)
Phased Array Ultrasonic Testing (PAUT)
Digital Radiography
Alternating Current Field Measurement
(ACFM)
Acoustic Emission (AE)
Laser Shearography
Remote Field Eddy Current
Magnetic Flux Leakage (MFL)
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Use of NDT methods – WHY?
• Flaw Detection and Evaluation
• Dimensional Measurements
• Structure and Microstructure
Characterization
• Estimation of Mechanical and Physical
Properties
• Material Sorting and Chemical Composition
Determination
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Application of NDT methods
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Application of NDT methods
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Application of NDT methods
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HSE Best Practice Guides
• Part 1 – Manual Ultrasonic Inspection
• Part 2 – Magnetic Particle and Dye
Penetrant Inspection
• Part 3 – Radiographic Inspection in
Industry
• Part 4 – Ultrasonic Sizing Errors and their
Implication for Defect Assessment
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HSE Best Practice Guides – Scope
• The measures contained in the documents ‘are
recommended by the HSE’ for the conduct of UT,
MT, PT & RT
• ‘They are intended to promote the adoption of
good practice and apply to in-service inspection
of existing plant and to repairs’
• ‘The guidelines could also be applicable to the
inspections carried out during the manufacture of
new or replacement plant’
• They contain ‘notes on good practice which are
not compulsory but which you may find helpful in
considering what you need to do’
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HSE Best Practice Guide
Sources
• Existing literature regarding the reliability of the application of each
method.
• Collective experience and expertise of the committee.
Conclusions
• If incorrectly chosen or incorrectly applied, inspection methods can
be ineffective. Defects may be overlooked or, alternatively, spurious
indications may be mistaken for genuine defects, leading to
unnecessary rejection of components or repairs.
Content
• An analysis of potential problems in method / technique application
together with a list of the measures which can be adopted in
response.
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HSE Best Practice Guide – MT & PT
3. CURRENT PRACTICE FOR DESIGN AND CONTROL OF
INSPECTIONS
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Many inspections are designed on the basis of a national or international
standard.
Procedure for the inspection is frequently written to reflect simply the
requirements of the standard in terms of the application of the equipment and
the consumables. However, technique sheets are often provided to reflect plant
and technique details.
The authority to approve a procedure for a specific inspection based on the
more general requirements of a code or standard requires skills and
qualifications additional to those required of the operators who apply the
inspection in the field.
Such qualifications are denoted as MT or PT Level 3 and involve demonstrating
a greater understanding of the particular inspection method than expected of the
Level 1 or 2 operators who normally carry out the inspection.
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HSE Best Practice Guide – MT & PT
4. THE NEED FOR ADDITIONAL REQUIREMENTS (selected items)
• Defect type
– Inspection design should be based on defect descriptions (why?)
– Inspection procedures should be designed or approved by an MT or PT Level 3
inspector as appropriate.
• Component Geometry
– The specific geometry and magnetic properties (for MT) of the component
should be considered when designing the inspection procedure.
• Component Material
– Inspection procedures for non-standard materials should be designed or
approved by MT/PT Level 3 inspectors as appropriate with specific knowledge
of such inspections. The procedure should be developed using representative
test pieces in the same material as the component if the Level 3 judges that this
is necessary.
• Operator performance
– Operators should be given practice on realistic test pieces prior to the
inspection if judged beneficial by the Level 3 inspector.
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HSE Best Practice Guide
5. INSPECTION IMPROVEMENTS AND COMPONENT RISK
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A major factor in determining which additional measures should be used is the
role of the inspection and the effectiveness required from it in reducing the risk
of component failure.
The risk of component failure is determined by a combination of both the
consequence and the probability of failure.
Inspection effectiveness is assigned a value of 1 (low), 2 or 3 (high) according to
the reduction of probability of failure that it produces in a particular case.
To reduce the probability of a component failure from high to low would require
a high level of inspection effectiveness, whereas to reduce the probability from
medium to low would require a medium level inspection effectiveness
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POD
• Probability of Detection
Probability of detecting a defined flaw type and size in the
area covered by the inspection method.
'the probability of detecting a crack in a given size group under
the inspection conditions and procedures specified'
‘…what is the smallest flaw that can be detected by an NDT method?’
‘…what is the largest flaw that can be missed?’
• Inspection Effectiveness
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Procedure
Content
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Scope
Standards and References
Definitions
Safety
Personnel
Identifications and datum points
Surface preparation
Extent of inspection
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Equipment specification
Equipment calibration
Equipment checks
Assessment of test results
Reporting of test results
Non-compliance statement
Attachments
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Technique
Content
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Foreword, status and authorization
Personnel
Apparatus to be used
Product/area to be tested
Test conditions
Detailed instructions for
application of test
Recording and classifying results
Reporting
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Codes – BS EN ISO 583-1
For any ultrasonic examination an examination procedure shall be established.
….at least the following shall be included as applicable
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Description of component
Reference documents
Qualification and certification of examination personnel
State of examination
Preparation of examination surfaces
Coupling medium
Description of examination equipment
Environmental conditions
Calibration and settings
Scanning plan
Description and sequence of examination operations
Evaluation and recording levels
Characterisation of imperfections
Acceptance criteria
Examination report
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Codes – ASME Article 4 - UT
Procedure shall establish a single value or range for each requirement
Requirement
Essential
Weld configurations to be examined, (thickness, dimensions and
base material product form (pipe, plate, etc.)
X
The surfaces from which the examination shall be performed
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Technique(s) (straight beam, angle beam, contact, immersion
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Angle(s) and mode(s) of wave propagation in the material
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Search unit type, frequencies, and element size(s)/shape(s)
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Special search units, wedges, shoes, or saddles, when used
X
Ultrasonic instrument(s)
Calibration [calibration block(s) and technique(s)]
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Directions and extent of scanning
Scanning (manual vs. automatic)
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Codes – ASME Article 4 – UT
Requirement
Scanning (manual vs. automatic)
Method for discriminating geometric from flaw
indications
Method for sizing indications
Computer enhanced data acquisition, when used
Scan overlap (decrease only)
Personnel performance requirements, when
required
Personnel qualification requirements
Surface condition (examination surface,
calibration block)
Couplant: brand name or type
Automatic alarm and/or recording equipment,
when applicable
Records, including minimum calibration data to
be recorded (e.g., instrument settings)
Essential
Non essential
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Codes – ASME Article 6 – PT
ASME V, Article 6, Requirements of an PT examination procedure
Requirement
Essential
Identification of change in type/family group of penetrant materials
(developers, emulsifiers, etc.)
Surface preparation (finishing and cleaning, including cleaning
solvent)
Method of applying penetrant
Method of removing excess surface penetrant
Hydrophilic or lipophilic emulsifier concentration and dwell time
Hydrophilic emulsifier concentration if sprayed
Method of applying developer
Min. and max. time periods between steps and drying aids
Decrease in penetrant dwell time (interpretation time)
Minimum light intensity
Surface temperature outside 5C to 52C or as previously qualified
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Codes – ASME Article 6 – PT
ASME V, Article 6, Requirements of an PT examination procedure
Requirement
Performance demonstration, when required
Materials, shapes, or sizes to be examined and the extent of
examination
Post-examination cleaning technique
Non-essential
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Codes – ASME Article 7 –MT
ASME V, Article 7, TABLE T-721
Requirements of an MAGNETIC PARTICLE examination procedure
Requirement
Essential
Magnetizing technique
Magnetizing current type or amperage outside range specified by
this Article or as previously qualified
Surface preparation
Magnetic particles (fluorescent/visible, particle size, wet/dry)
Method of particle application
Method of excess particle removal
Minimum light intensity
Existing coatings, greater than the thickness demonstrated
Nonmagnetic surface contrast enhancement, when utilized
Performance demonstration, when required
Examination part surface temperature outside of the temperature
of the temperature range recommended by the manufacturer of
the particles or as previously qualified
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Procedure Qualification
ASME Code Case 2235 – Enables use of UT in lieu of RT for ASME
VIII Division 1 and 2 vessels
• Requires the procedure to be demonstrated on a
qualification block representative of the components to
be inspected (dimensions, configuration, material)
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NDT Certification
Central Certification
Employer Based
Certification
• Standardisation
• Harmonisation
• Independence
• Training and
certification directed
closely at the needs
of the particular
company's NDT
business.
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NDT Certification
Central Certification
• EN 473
• ISO 9712
Employer Based
• EN 4179
• SNT-TC-1A
• CP 189
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TWI’s NDT Services
• Levels 2 and 3 services eg UT and LRUT:
 Procedure approval
 Procedure qualification/validation
 eg to ENIQ or ASME methodology
 Procedure
 Audits
 Working practice assessments
 SNT-TC1A supervision.
• NDT as part of Inspection, Assessment and Repair
 Critical defect sizing for ECAs
 Procedure development
 Inspection of repairs
 Defect monitoring
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