Section
5 Non-destructive examination
5.1 General NDE requirements
5.1.1 Prior to
the final acceptance of materials, surface inspection and verification
of dimensions, non-destructive examination is to be carried out in
accordance with the requirements detailed in this Section and subsequent
Chapters of these Rules.
5.1.2 It is the
manufacturer’s responsibility for maintaining the required tolerances
and making the necessary measurements. Periodic surveys by the Surveyor
do not absolve the manufacturer from this responsibility.
5.1.3 When there
is visible evidence to doubt the soundness of any material or component,
such as flaws in test specimens or suspicious surface marks, the manufacturer
is expected to prove the quality of the material by a suitable method.
5.1.4 Acceptance
criteria are detailed in subsequent Chapters of these Rules. Alternative
specifications may be submitted for consideration, provided they demonstrate
equivalence to these Rules.
5.1.5 It is the manufacturer’s responsibility to ensure that all NDE and visual
inspections are carried out in a controlled and consistent manner by certified
personnel, in accordance with the approved and applicable NDE procedures, for all
methods. This responsibility includes the collation and provision of accurate reports,
which shall be transmitted as appropriate to LR, and in all cases be available upon
request to the Surveyor.
5.1.6 NDE testing may be witnessed at the discretion of the LR Surveyor and wherever
specifically stated within LR Rules.
5.2 Personnel qualifications
5.2.1 Personnel carrying out non-destructive examination and interpreting the
results of non-destructive examination shall be certified to the appropriate level of a
nationally recognised scheme. This requirement also extends to advanced methods, which
include, but are not limited to, Phased Array Ultrasonic Testing (PAUT), Time of Flight
Diffraction (TOFD), and digital radiography (RT-D). Schemes such as ISO 9712, ACCP (ASNT
Central Certification Program) or SNT-TC-1A fulfil this certification requirement. Other
nationally recognised schemes may be acceptable, and shall be agreed with LR.
Furthermore, the personnel shall be certified to the appropriate industry sector for the
product type which they are examining.
5.2.2 Level 1 personnel are not permitted to interpret results to Codes or Standards.
5.2.3 When certification of personnel is made on an in-house basis under a scheme
such as SNT-TC-1A, practical examinations are to be relevant to material, product type,
joint configuration, material thickness and acceptance criteria of items inspected for
Classification purposes.
5.2.4 Personnel qualifications of NDE operators are to be randomly checked by the
Surveyor.
5.3 Requirements for suppliers of NDE services
5.3.1 The shipyard, fabricator, or manufacturer may have internal NDE services
(e.g. internal NDE department), or may acquire external provision of these services
from an NDE firm. The NDE provision, whether from internal resource, or external
provider, hereinafter shall be known as the supplier.
5.3.2 The supplier carrying out NDE services shall document all controls
necessary to ensure that competent and appropriate NDE services can be provided.
These include (but are not limited to):
- a quality management system covering all necessary and
relevant information and processes, enabling effective NDE operations;
- training and certification of NDE personnel;
- responsibilities of Supervisors and Operators;
- equipment
- procedures and work instructions;
- control and use of sub-contractors (as applicable); and
- reporting.
5.3.3 Documents detailing control of NDE operations and processes shall be
available to the Surveyor upon request. These include items such as:
- organisation and management structure, including any
subsidiaries;
- quality management system;
- procedures and work instructions;
- details of training requirements, and Written Practice
(if applicable) according to SNT-TC-1A;
- roles and responsibilities of supervising and
practitioner personnel;
- company experience;
- equipment controls, including guidelines for use of
equipment; and
- customer feedback, relevant complaints, and any legal
proceedings against the company (historical or present); and
- any information on other activities which may present a
conflict of interest.
5.3.4 The quality management system shall contain details covering, as a
minimum, the following items:
- Training and certification processes, including visual
acuity;
- Work procedures and instructions;
- Maintenance of documents, records and standards;
- Maintenance, control, and calibration of equipment;
- Processes for supervision and effective control of
operations;
- Traceability of records and equipment;
- Code of conduct for activities;
- Corrective and preventive actions; and
- internal and supplier audits (as applicable).
5.3.5 The supplier of NDE services should satisfy the requirements of a Type A
or Type B inspection body, as described in ISO/IEC 17020; however, formal
certification to ISO/IEC 17020 is not required.
5.3.6 The supplier shall have employed at least one Level III in the
organisation, who is deemed a Supervisor, with applicable responsibilities
commensurate with this title, and as described in the quality management system and
work processes. The Level III Supervisor shall be certified to an externally
accredited scheme, i.e. they shall not be appointed under an ‘in-house’ scheme.
5.3.7 The supplier may acquire external provision of independent Level III
services to supplement any additional NDE methods which the Level III Supervisor may
not be certified for.
5.4 Non-destructive examination methods
5.4.1 Non-destructive examination methods are to comply with the relevant
requirements of these Rules.
5.4.2 The surfaces under inspection are to be clean, dry and free from scale, oil,
grease, dirt or paint so that there are no contaminants or entrapped material that may
impede the inspection media, especially penetrant media, and are to be free of
irregularities that may mask or interfere with interpretation of results.
5.4.3 Visual testing personnel are to confirm that the surface condition is acceptable prior
to carrying out any further NDE inspections. Visual testing shall be conducted in
accordance with a recognised National or International standard agreed between the
Shipbuilder and Surveyor.
5.5 Non-destructive examination procedures and
work instructions
5.5.1 All non-destructive
examinations are to be carried out to a procedure that is representative
of the item under inspection. As a minimum the procedures are to be
in accordance with the following:
-
Procedures are to identify the component to be examined, the NDE
method, the equipment to be used and the full extent of the examinations including
any test restrictions.
-
Procedures are to specify
the qualification and certification requirements of the inspection
personnel to be employed.
-
Procedures are to state
the degree of surface preparation required and the methods of preparation
to be used before the examinations are made.
-
Procedures are to state
the reference standards for testing and the acceptance criteria to
be applied to the results of the inspections.
-
Procedures are to include
the requirement for components to be positively identified and for
a datum system or marking system to be applied to ensure repeatability
of inspections.
-
Procedures are to identify
any requirements for increasing the extent of applied NDE where defects
have been found during spot examination.
-
Procedures are to identify
reporting requirements.
-
Procedures are to be reviewed by the Surveyor to ensure that they are
appropriate for the product type.
-
Procedures are to include
the method and requirements for equipment calibrations and functional
checks.
-
Procedures are to be approved by an Operator or Supervisor qualified
to Level III in accordance with a recognised certification scheme or body. The
Level III shall be certified in the method which is relevant to the testing
procedure.
-
The Surveyor will review
procedures for compliance with this Section.
5.5.2 The shipyard,
fabricator or manufacturer may submit other Codes or Standards for
consideration by LR, providing they are equivalent to these Rules.
Where no agreed acceptance standard is in place, the acceptance levels
contained in the subsequent Chapters of these Rules are to apply.
5.5.3 In the event
that proposed acceptance criteria are not considered to be equivalent
to these Rules, the criteria may be submitted for special consideration.
5.6 Non-destructive examination reports
5.6.1 NDE reports are to include all information required to identify how the
examination was executed and are to include the following information where
appropriate:
- Date of test, and date of test report (if different from test).
- Name and qualification of Operator with signatures of the
Operator.
- Details of the component identification, ship hull number
(where applicable), description of test location, purpose of test and volume
examined.
- Material type, grade, stage of manufacture (where applicable), product
form, geometrical configuration, dimensions and thickness.
- Heat treatment status, where applicable.
- Weld type, weld location, length of inspected weld, weld
process and procedure, and weld configuration, where applicable to welded structures
or components. Additionally, for ship hull welds, the number of repairs is to be
recorded if a specific area is repaired more than twice.
- Surface condition and surface test temperature.
- Test procedure, testing standards, and testing level (as
applicable).
- Equipment used, including instrument manufacturer, type of
instrument, and any identification numbers (as applicable).
- Test results with a map or record of reportable and/or reject
indications, giving location, datum (and any appropriate coordinate system),
dimensions and nature of indications, and a statement of acceptance/non-acceptance,
as appropriate.
- Reference to acceptance criteria and evaluation in accordance
with these criteria.
- Calibration details of the equipment and reference samples,
as appropriate to the test method.
- Viewing conditions.
- Details of software used (where applicable).
- Method and values used for range and sensitivity settings (where
applicable).
- Details of any signal processing and scan increment settings
(where applicable).
- Access limitations and any deviations from standards or
procedures.
- Reference to the raw data file(s) (where applicable).
5.6.2 Non-destructive examination inspection records are to be maintained for at least 7
years.
5.7 Liquid penetrant testing
5.7.1 Liquid penetrant testing (PT) is to be conducted in accordance with ISO
3452-1 or a recognised National or International Standard with the extent of the PT
being in accordance with the approved plans and to the satisfaction of the
Surveyor.
5.7.2 The temperature of parts examined is to typically be between 5ºC and 50ºC. Outside
this temperature range, special high/low temperature penetrant and reference
comparator blocks are to be used upon agreement with LR.
5.7.3 In addition to any of the general requirements of Ch 1, 5.6 Non-destructive examination reports, PT reports
are to include the following specific items:
- Type of penetrant, cleaner, and developer used.
- Penetration and development timings.
- Viewing/lighting conditions.
5.7.4 The PT acceptance criteria for welds are based on the general requirements of ISO
23277 Level 2.
5.8 Magnetic particle testing
5.8.1 Magnetic particle testing (MT) is to be conducted in accordance with ISO 17638 or a
recognised National or International Standard with the extent of the MT being in
accordance with the approved plans and to the satisfaction of the Surveyor
5.8.2 In addition to any of the general requirements of Ch 1, 5.6 Non-destructive examination reports, MT
reports are to include the following specific items:
- Type of magnetisation.
- Magnetic field strength.
- Detection media.
- Viewing/lighting conditions.
- Demagnetisation, if required.
5.8.3 The MT acceptance criteria for welds are based on the general requirements of ISO
23278 Level 2.
5.9 Radiographic testing
5.9.1 Radiographic testing (RT) is to be conducted in accordance with ISO 17636-1 or a
recognised National or International Standard with the extent of the RT being in
accordance with the approved plans and to the satisfaction of the Surveyor.
5.9.2 Procedures for radiography are to specify the acceptable optical density within the
area of interest on the radiograph.
5.9.3 The minimum optical density within the area of interest on a radiograph is to be
equal to or greater than 2,0 for gamma ray and 1,8 for X-ray. A maximum density of
4,0 is acceptable if a suitable radiographic film viewer is capable of providing a
sufficiently high intensity light source.
5.9.4 In addition to any of the general requirements of Ch 1, 5.6 Non-destructive examination reports, RT
reports are to include the following specific items:
- Type and size of radiation source (width of radiation
source), X-ray voltage.
- Type of film/designation and number of films in each film
holder/cassette.
- Number of exposures or radiographs.
- Type of intensifying screens where applicable.
- Exposure technique, time of exposure and source to film
distance.
- Distance from radiation source to weld.
- Distance from source side of the weld to the radiographic
film.
- Approximate angle of radiation beam through the weld.
- Sensitivity, type and position of IQI.
- Optical density.
- Geometric un-sharpness.
- Specific acceptance class criteria for RT.
- Film development process and details.
5.9.5 The control of documentation, unprocessed original images and digitally processed
images (where applicable) is to be in accordance with the approved procedure and
quality management system.
5.9.6 The RT acceptance criteria for welds are based on the general requirements of ISO
10675-1 Level 2, and Level 3 for Lack of Fusion type defect.
5.10 Ultrasonic testing
5.10.1 Ultrasonic testing (UT) is to be conducted in accordance with ISO 17640 (testing
procedure), ISO 23279 (characterisation, where applicable) and ISO 11666 (acceptance
levels) or to a recognised accepted National or International standard.
5.10.2 In addition to any of the general requirements of Ch 1, 5.6 Non-destructive examination reports, UT
reports are to include the following specific items:
- Type and identification of ultrasonic equipment used
(instrument manufacturer, model and serial number), transducers (instrument
manufacturer, serial number, angle and frequency) and type of couplant
(brand).
- Sensitivity levels calibrated and applied for each
transducer.
- Amount of transfer loss correction applied and type of
reference blocks used.
- Signal response used for defect detection.
- Indications interpreted as failing to meet acceptance
criteria.
5.10.3 For satisfactory quality control, the method of reviewing and evaluating UT reports
is to be in accordance with the approved procedure and to the satisfaction of the
Surveyor.
5.10.4 The UT acceptance criteria for welds are based on the general
requirements of ISO 11666 Quality Level C and Acceptance Level 3 and apply to the
examination of full penetration ferritic steel welds with thickness from 8 mm to 100
mm. The nominal frequency of transducers/probes is to be between 2 MHz and 5 MHz.
Examination procedures for other types of welds, material, thicknesses above 100 mm,
assessment of indications not covered in these rules and examination conditions are
to be submitted for consideration by LR.
5.10.5 Sensitivity settings/ levels are based on technique 1 of ISO 11666 based on 3 mm
diameter side drilled holes and the acceptance criteria for welds are based on the
general requirements of ISO 11666 Level 3.
5.11 Advanced NDE methods
5.11.1 Advanced NDE (ANDE) methods may be utilised instead of, or complementary to, existing
NDE methods, as applicable and as referenced throughout these Rules. The technical
requirements and acceptance standards for each of the methods are described within
the appropriate sections of these Rules.
5.11.2 ANDE may be performed, as applicable, on base materials, welds, and components. The
acceptance criteria when using ANDE methods shall be the same as for existing NDE
methods, unless explicitly stated within the appropriate chapters.
5.11.3 The following terms and definitions for advanced NDE will be referred to hereinafter
within these Rules:
- ANDE: Advanced non-destructive examination.
- RT-D: Digital radiography (a term for digital
radiographic testing and image storage, other than film radiography. This
method utilises digital detectors).
- RT-S (an RT-D method): Radioscopic testing with
digital image acquisition (dynamic ≥12bit). For the purposes of these Rules,
this method is taken to mean a digital detector utilising DDAs (digital
detector arrays), usually consisting of a flat panel detector (or a series
of detectors).
- RT-CR (an RT-D method): Testing with computed
radiography using storage phosphor imaging plates.
- PAUT: Phased Array Ultrasonic Testing.
- TOFD: Time of Flight Diffraction (an ultrasonic
testing method).
- AUT: Automated Ultrasonic Testing/Examination. A
technique for ultrasonic examination performed with equipment and search
units that are mechanically mounted and guided, remotely operated, and
motor-controlled (driven) without adjustments by the technician. The
equipment used to perform the examinations is capable of recording the
ultrasonic response data, including the scanning positions, by means of
integral encoding devices such that imaging of the acquired data can be
performed. Furthermore, post-testing image analysis with respect to
positional location may be obtained from the captured and stored data.
- SAUT: Semi-Automated Ultrasonic
Testing/Examination. A technique of ultrasonic examination performed with
equipment and search units that are mechanically mounted and guided,
manually assisted (driven), and which may be manually adjusted by the
technician. The equipment used to perform the examinations is capable of
recording the ultrasonic response data, including the scanning positions, by
means of integral encoding devices such that imaging of the acquired data
can be performed. Furthermore, post-testing image analysis with respect to
positional location may be obtained from the captured and stored data.
5.12 Digital radiography
5.12.1 RT-D methods may be of the RT-S (DDA) type or RT-CR type, as applicable
to the component or configuration of the test item.
5.12.2 RT-D methods may be used on any material grade and in general on any
thickness range, as applicable to the penetrating capability of the radiation energy
and the radiation source, and within any limits as identified in the procedure.
5.12.3 All examinations utilising RT-D methods are to be undertaken using an
approved procedure. In addition to the general procedural requirements, as specified
in Ch 13, 2.12 Non-destructive examination of steel welds
instructions, procedures for RT-D shall conform to, and specify the following
requirements (where applicable):
- Technical requirements concerning digital radiography
are to be based on ISO 17636-2 and standards referenced therein, or other
recognised standards acceptable to LR (upon agreement).
- Any variation to applying the standard (e.g. IQI
placement of standard or duplex wire IQI) shall be agreed with LR.
- The procedure is to include the technical information
(as applicable) shown in Table 1.5.1 Specific requirements of a
digital radiography procedure.
Table 1.5.1 Specific requirements of a
digital radiography procedure
Requirement:
|
Material types or weld configurations to be
examined, including thickness dimensions and material product
form (castings, forgings, pipe, plate, etc.)
|
Digitising system description:
|
Manufacturer and model no. of digitising
system
|
Physical size of the usable area of the image
monitor
|
Film size capacity of the scanning device
|
Spot size(s) of the film scanning system
|
Image display pixel size as defined by the
vertical/horizontal resolution limit of the monitor
|
Illuminance of the video display
|
Data storage medium
|
Digitising technique:
|
Digitiser spot size (in microns) to be used
|
Loss-less data compression technique, if
used
|
Method of image capture verification
|
Image processing operations
|
Time period for system verification
|
Spatial resolution used:
|
Contrast sensitivity (density range
obtained)
|
Dynamic range used
|
Spatial linearity of the system
|
Material type and thickness range
|
Source type or maximum X-ray voltage used
|
Detector type
|
Detector calibration
|
Minimum source-to-object distance
|
Distance between the test object and the
detector
|
Source size
|
Test object scan plan (if applicable)
|
Image quality measurement tools
|
Image Quality Indicator (IQI)
|
Wire image quality indicator
|
Duplex image quality indicator
|
Image Identification Indicator
|
Testing levels, acceptance levels and/or recording
levels
|
Personnel qualification requirements
|
Surface condition
|
Records, including minimum calibration data to be
recorded
|
Environmental and safety issues
|
5.12.4 The testing class for RT-D methods is to be class B techniques, as per ISO 17636-2.
For circumferential weld testing, the minimum number of exposures may correspond to
the requirements of class A.
5.12.7 The acceptance criteria for other products, components, or base materials, are to be
the same for film radiography (where applicable).
5.12.8 A test report is to be issued for all examinations utilising RT-D
methods. In addition to the general reporting requirements, as specified in Ch 1, 5.6 Non-destructive examination reports, reports for
RT-D additionally record the following information, as applicable:
- System of marking used on the test item. Where the nature of
the material and/or its service conditions do not permit permanent marking, the
location may be recorded by means of accurate sketches or photographs.
- Radiation source, type and size of focal spot and
identification of equipment used.
- Detector, screens, filters (where applicable) and detector
basic spatial resolution.
- Detector position plan, and source-to-detector
distance.
- Tube voltage and current, or source type and activity, as
applicable.
- Exposure duration.
- Type and position of image quality indicators (IQIs),
including duplex wire IQIs.
- Procedural requirements and achieved normalised
signal-to-noise ratio (SNRN) for RT-S, or procedural requirements and achieved
grey values and/or SNRN for RT-CR, as applicable.
- For RT-S: type and parameters such as gain, frame time,
frame number, pixel size, calibration procedure.
- For RT-CR: scanner type and parameters such as pixel size,
scan speed, gain, laser intensity, laser spot size.
- Image processing parameters used, e.g. of the digital
filters.
- Details of any software used, such as evaluation software,
or defect simulation software (where applicable).
- Details of any image magnification or image enhancing
parameters within the evaluation software.
5.13 Phased array ultrasonic testing (PAUT)
5.13.1 PAUT may generally be used be used on any material, configuration, and thickness
range, as applicable to ultrasonic testing, and within any limits as identified in
the procedure and as per specific requirements in LR Rules.
5.13.2 The following requirements are to be taken into consideration when using the PAUT
method:
- Depending on the complexity of the item under test and
the access to surfaces, there may be a requirement for additional scans
and/or complementary NDE techniques to ensure that full coverage of the item
is achieved.
- PAUT of welds is normally to include an ‘E’ scan (or
linear scan) of the fusion face, together with other scans as defined in the
specific test technique. Exceptions to this requirement concerning linear
scans are given in Ch 1, 5.13 Phased array ultrasonic testing (PAUT) 5.13.3.(g)
- The surface preparation for utilising the PAUT method is
to satisfy the requirements for ultrasonic testing. In exceptional cases
where there is a requirement to carry out PAUT through paint, the
suitability and sensitivity of the test is to be confirmed through an
appropriate transfer correction method defined in the procedure. In all
cases, if transfer losses exceed 12 dB, the reason is to be considered and
further preparation of the scanning surfaces is to be carried out, if
applicable. If testing is done through paint, then the procedure is to be
qualified on a painted surface.
- PAUT method scanning will usually involve the use of AUT
or SAUT scanning techniques and equipment. Where this is not possible
(perhaps due to the configuration or complexity of the test item), or a
specific requirement necessitates manually operated scanning, PAUT manual
scanning is permitted on agreement with LR, and the reasons documented why
AUT or SAUT cannot be utilised. In all cases, accurate identification of
scans and reference to a datum point is required.
5.13.3 All examinations utilising PAUT are to be undertaken using an approved
procedure. In addition to the general procedural requirements, as specified in Ch 13, 2.12 Non-destructive examination of steel welds, procedures for PAUT shall conform to, and specify the following
requirements (where applicable):
- Technical requirements concerning PAUT are to be based
on ISO 13588, ISO 18563-1, ISO 18563-2, ISO 18563-3, and ISO 19285, and
standards referenced therein, or other recognised standards acceptable to
LR.
- Any variation to applying the standards is to be agreed
with LR. When an essential variable in Table 1.5.2 Specific requirements of a
PAUT procedure changes from the specified
value, or range of values, procedure shall require requalification.
- When a nonessential variable in Table 1.5.2 Specific requirements of a
PAUT procedure changes from the specified
value, or range of values, requalification of the written procedure is not
required
- All changes of essential or nonessential variables from
the value, or range of values, specified by the procedure are to require
revision of, or an addendum to, the procedure.
- The purpose of the testing and the volume to be
inspected is to be defined in the testing procedure.
- A scan plan is to be provided as part of the procedure,
and is to show the beam coverage, probe locations, the weld thickness and
the weld geometry.
- For techniques involving amplitude-only based evaluation
of indications, it is a requirement that an ‘E’ scan (or linear scan) is to
be utilised to scan the fusion faces of welds, so that the sound beam is
perpendicular to the fusion face ± 5º. This requirement may be omitted if an
‘S’ (or sectorial) scan can be demonstrated to verify that discontinuities
at the fusion face can be detected and sized, using the stated procedure.
This demonstration is to utilise reference blocks containing suitable
reflectors in location of the fusion zone.
- A reference block shall be used to determine the
adequacy of the testing (e.g. coverage, sensitivity setting). The design and
manufacture of reference blocks is to be in accordance with ISO 13588 or
recognised equivalent standards acceptable to LR.
- Indications detected when applying the testing procedure
are usually to be evaluated by length and amplitude. Evaluation of
indications by length and height are usually for project specific or ECA
(Engineering Critical Assessment) requirements and shall be specially agreed
with LR.
- Indication assessment and acceptance standard for steel
welds is to be the same as for ultrasonic testing and is shown in Table
13.2.7 Acceptance criteria for ultrasonic and Phased Array testing, which is
equivalent to ISO 19285 and ISO 11666 level 3. Other acceptance criteria may
be specially considered by LR upon request.
- The sizing techniques include reference levels, Time
Corrected Gain (TCG), Distance Gain Size (DGS) and 6 dB drop. The 6 dB drop
method is only to be used for measuring the indications larger than the beam
width.
- The procedure is to include the technical information
(as applicable), shown in Table 1.5.2 Specific requirements of a
PAUT procedure.
Table 1.5.2 Specific requirements of a
PAUT procedure
Requirement
|
Essential Variable
|
Nonessential Variable
|
Material types or weld
configurations to be examined, including thickness dimensions
and material product form (castings, forgings, pipe, plate,
etc.)
|
X
|
…
|
The surfaces from which the
examination shall be performed
|
X
|
…
|
Technique(s) (straight
beam, angle beam, contact, and/or immersion)
|
X
|
…
|
Angle(s) and mode(s) of
wave propagation in the material
|
X
|
…
|
Search unit type,
frequency, element size and number, pitch and gap dimensions,
and shape
|
X
|
…
|
Focal range (identify
plane, depth, or sound path)
|
X
|
…
|
Virtual aperture size
(i.e., number of elements, effective height1 and
element width)
|
X
|
…
|
Focal laws for E-scan and
S-scan (i.e. range of element numbers used, angular range used,
element or angle increment change)
|
X
|
…
|
Special search units,
wedges, shoes, or saddles, when used
|
X
|
…
|
Ultrasonic
instrument(s)
|
X
|
…
|
Calibration [calibration
block(s) and technique(s)]
|
X
|
…
|
Directions and extent of
scanning
|
X
|
…
|
Scanning (manual or
automatic)
|
X
|
…
|
Method for sizing
indications and discriminating geometric from flaw indications
|
X
|
…
|
Computer enhanced data
acquisition, when used
|
X
|
…
|
Scan overlap (decrease
only)
|
X
|
…
|
Personnel performance
requirements (where required)
|
X
|
…
|
Testing levels, acceptance
levels and/or recording levels
|
X
|
…
|
Personnel qualification
requirements
|
…
|
X
|
Surface condition
(examination surface, calibration block)
|
…
|
X
|
Couplant (brand name or
type)
|
…
|
X
|
Post-examination cleaning
technique
|
…
|
X
|
Automatic alarm and/or
recording equipment, when applicable
|
…
|
X
|
Records, including minimum
calibration data to be recorded (e.g. instrument
settings)
|
…
|
X
|
Environmental and safety
issues
|
…
|
X
|
Note 1.
Effective height is the distance from the outside edge of the
first to last element used in the focal law.
|
5.13.4 The acceptance criteria for other products, components, or base
materials, is to be the same for ultrasonic testing (where applicable).
5.13.5 A test report is to be issued for all examinations utilising PAUT. In
addition to the general reporting requirements, as specified in Ch 1, 5.6 Non-destructive examination reports,
reports for PAUT are to record the following information, as applicable:
- Manufacturer, type, frequency of phased array probes
including number and size of elements, material and angle(s) of wedges, with
identification numbers, where applicable.
- Details of reference block(s) with identification numbers,
where applicable.
- Type of couplant used.
- Increment (E-scans), and/or angular increment
(S-scans).
- Element pitch and gap dimensions.
- Focus (calibration should be the same as scanning).
- Virtual aperture size, i.e. number of elements and element
width.
- Element numbers used for focal laws.
- Manufacturer documentation on the permitted wedge angular
range.
- Documented calibration, TCG and angle gain
compensation.
- Scan plan.
- Phased array images of at least those locations where
relevant indications have been detected (printed on the report), and
additionally, all images and data available in soft copy format.
- Reference points and details of the coordinate system.
- Details of any software used, including (but not limited to)
scan plan set-up and component testing coverage (e.g. ray-tracing software),
evaluation software, defect simulation software (where applicable).
5.14 Time of Flight Diffraction (TOFD)
5.14.1 TOFD may generally be used on any material, configuration, and thickness range, as
applicable to ultrasonic testing, and within any limits as identified in the
procedure and as per specific requirements in LR Rules. Generally, the TOFD method
is more limited in its application than PAUT.
5.14.2 The following requirements are to be taken into consideration when using the TOFD
method:
- Depending on the complexity of the item under test and
the access to surfaces, there may be a requirement for additional scans
and/or complementary NDE techniques to ensure that full coverage of the item
is achieved.
- Due to the nature of the TOFD method, there is a
possibility that the scan plan may reveal weld volume zones that will not
receive full TOFD coverage (commonly known as dead zones, either in the
lateral wave, back wall, or both). If the scan plan reveals that these dead
zones are not adequately inspected, then further TOFD scans and/or
complementary NDE methods are to be applied to ensure full inspection
coverage.
- The surface preparation for utilising the TOFD method is
to satisfy the requirements for ultrasonic testing. In exceptional cases
where there is a requirement to carry out TOFD through paint, the
suitability and sensitivity of the test is to be confirmed through an
appropriate transfer correction method defined in the procedure. In all
cases, if transfer losses exceed 12 dB, the reason is to be considered and
further preparation of the scanning surfaces shall be carried out, if
applicable. If testing is done through paint, then the procedure is to be
qualified on a painted surface.
- TOFD method scanning will usually involve the use of AUT
or SAUT scanning techniques and equipment. Manual scanning is not usually
appropriate to the TOFD method due to the nature of the equipment and
scanning technique; however, it will be specially considered if demonstrated
to be effective for specific applications.
5.14.3 All examinations utilising TOFD are to be undertaken using an approved
procedure. In addition to the general procedural requirements, as specified in Ch 13, 2.12 Non-destructive examination of steel welds, procedures for TOFD are to conform to, and specify the following
requirements (where applicable):
- Technical requirements concerning TOFD are to be based
on ISO 10863 and ISO 15626, and standards referenced therein, or other
recognised standards acceptable to LR (upon agreement).
- Any variation to applying the standards is to be agreed
with LR. When an essential variable in Table 1.5.3 Specific requirements of a
TOFD procedure changes from the specified value, or range of values,
procedure shall require requalification.
- When a nonessential variable in Table 1.5.3 Specific requirements of a
TOFD procedure changes from the specified value, or range of values,
requalification of the written procedure is not required.
- All changes of essential or nonessential variables from
the value, or range of values, specified by the procedure are to require
revision of, or an addendum to, the procedure.
- The purpose of the testing and the volume to be
inspected is to be defined in the testing procedure.
- A scan plan is to be provided as part of the procedure,
and is to show the beam coverage, probe locations, the weld thickness and
the weld geometry.
- A reference block shall be used to determine the
adequacy of the testing (e.g. coverage, sensitivity setting). The design and
manufacture of reference blocks is to be in accordance with ISO 10863 or
recognised equivalent standards acceptable to LR.
- Indications detected when applying the testing procedure
are usually to be evaluated by length and height.
- Indication assessment and acceptance standard for welds
is shown in Table 13.2.8 Acceptance criteria for TOFD
testing1, which is equivalent to ISO 15626 level 2. Other
acceptance criteria, including project specific or ECA (Engineering Critical
Assessment) requirements are to be specially agreed with LR.
- The sizing of indications is to be as per the
requirements of ISO 10863, or recognised equivalent standards acceptable to
LR.
- The procedure is to include the following technical
information (as applicable), as shown in Table 1.5.3 Specific requirements of a
TOFD procedure.
Table 1.5.3 Specific requirements of a
TOFD procedure
Requirement
|
Essential Variable
|
Nonessential Variable
|
Weld configurations to be examined, including
thickness dimensions and material product form
|
X
|
…
|
The surfaces from which the examination shall be
performed
|
X
|
…
|
Angle(s) of wave propagation in the
material
|
X
|
…
|
Search unit type(s), frequency (or frequencies),
and element size(s)/shape(s)
|
X
|
…
|
Special search units, wedges, shoes, or saddles,
when used
|
X
|
…
|
Ultrasonic instrument(s) and software(s)
|
X
|
…
|
Calibration [calibration block(s) and
technique(s)]
|
X
|
…
|
Directions and extent of scanning
|
X
|
…
|
Scanning method (including manual or
automatic)
|
X
|
…
|
Data sampling spacing (increase only)
|
X
|
…
|
Method for sizing indications and discriminating
geometric from flaw indications
|
X
|
…
|
Computer enhanced data acquisition, when
used
|
X
|
…
|
Scan overlap (decrease only)
|
X
|
…
|
Personnel performance requirements, when
required
|
X
|
…
|
Testing levels, acceptance levels and/or recording
levels
|
X
|
…
|
Personnel qualification requirements
|
…
|
X
|
Surface condition (examination surface, calibration
block)
|
…
|
X
|
Couplant (brand name or type)
|
…
|
X
|
Post-examination cleaning technique
|
…
|
X
|
Automatic alarm and/or recording equipment, when
applicable
|
…
|
X
|
Records, including minimum calibration data to be
recorded (e.g. instrument settings)
|
…
|
X
|
Environmental and safety issues
|
…
|
X
|
5.14.4 Generally, TOFD is not suitable or applicable to cast copper alloys, steel castings,
or steel forgings. However, where it is used on steel and aluminium base materials,
the acceptance criteria are to be the same for ultrasonic testing (where
applicable).
5.14.5 A test report is to be issued for all examinations utilising TOFD. In
addition to the general reporting requirements, as specified in Ch 1, 5.6 Non-destructive examination reports,
reports for TOFD are to record the following information, as applicable:
- Manufacturer, type, frequency, element size and beam
angle(s) of probes, with identification numbers, where applicable.
- Details of reference block(s) with identification numbers,
where applicable.
- Type of couplant used.
- Details of TOFD setups.
- Scan plan, and details of offset scans (if required).
- TOFD images of at least those locations where relevant TOFD
indications have been detected (printed on the report), and additionally, all
images and data available in soft copy format.
- Reference points and details of the coordinate system.
- Details of any software used, including (but not limited to) scan plan set-up
and component testing coverage (e.g. ray-tracing software), evaluation software,
defect simulation software (where applicable).
5.15 ANDE method and procedure qualification
5.15.1 All ANDE is to undergo a qualification and demonstration program to determine the
suitability and the effectiveness of the proposed method, for the detection and
sizing of discontinuities. The intent of this program is to determine the general
capability of the ANDE methods, in demonstrating reasonable equivalence to the
existing NDE methods. Project specific requirements may require a more extensive
program than described herein.
5.15.2 The extent of the qualification demonstration is dependent upon the method and the
complexity of the testing regime, and the components under test.
5.15.3 The following documentation shall be submitted for review:
- All technical documentation of the ANDE, including
method procedure, history of previous method utilisation and qualification
program (where applicable), probability of detection (PoD) capability (where
applicable), agreed test samples and/or test blocks used for validation and
comparators, and any other technical information to support the
qualification programme, as requested by LR.
- The operating methodology and detailed extent of
utilisation, including all product forms, thickness, and weld configurations
(as applicable).
- Result of software simulation, where applicable.
5.15.4 Software simulation may be required, where applicable, for PAUT or TOFD techniques.
The simulation may include initial test set-up, scan plan, volume coverage, and
result image of the artificial flaw. In some circumstances, artificial defect
modelling/simulation may be needed or required by the project, and to be agreed with
LR.
5.15.5 The procedure qualification test for ANDE methods is to include the following steps
(as applicable):
- Review of available performance data for the inspection
system (detection capability and defect sizing accuracy).
- Identification and evaluation of significant parameters,
and their variability in determining accurate results.
- Planning and execution of a repeatable and reliable test
programme, which includes onsite demonstration, as per Ch 1, 5.15 ANDE method and procedure qualification 5.15.6.
- Documentation of results from the test program, to
demonstrate the effective repeatability and reliability of the ANDE
method.
- The data from the repeatability and reliability test
program is to be analysed with respect to the test samples or test blocks,
as agreed as part of the qualification program, and is to be presented in a
qualification program report.
- For PAUT and TOFD, the qualification block should
generally satisfy the requirements of ASME V, Article 14, Mandatory
Appendix II (intermediate level). Other test blocks may be used upon
agreement with LR. If accurate PoD or sizing error distributions need to be
evaluated, then the high-level qualification blocks are to be used, as per
ASME V, Article 14, Mandatory Appendix II.
- For PAUT and TOFD, other test samples containing actual
defects may also be used to determine method capability and accuracy, in
addition to the qualification blocks. These are to be agreed as part of the
initial documentation submission for the scope of the procedure
qualification program.
- The onsite demonstration process shall be witnessed by
LR.
- The manufacturer is to issue a final report detailing
the steps of the qualification program, including all technical details, and
results of the ANDE methods with respect to the qualification blocks and
test pieces.
5.15.6 An on-site demonstration of the ANDE capability shall be performed, and witnessed by
LR, and is to include, where applicable:
- Performance demonstration of the proposed ANDE method on
the agreed test welds/test pieces/qualification blocks, as appropriate.
- For the agreed qualification program test welds,
supplementary NDE is to be performed on an agreed proportion of these welds,
for cross checking and comparison with proposed and supplementary methods.
As an alternative to supplementary NDE cross-checking, other documented
reference techniques may be applied for comparison with ANDE results, upon
agreement with LR.
- Data analysis is to be performed in accordance with the
on-site demonstration activities. Where applicable and specially agreed, PoD
and sizing accuracy is also to be established.
- Where the results of inspection reviews do not conform
to the approved procedure, the inspection is to be suspended, and additional
qualification and demonstration is to be undertaken to account for any
identified nonconformity. This may include additional procedure development
and supporting technical information, as applicable.
- In such cases where nonconformities are identified, LR
may reject the results of ANDE activities until successful demonstration of
the method is achieved, and method application is performed successfully.
- LR may request a further cross-checking using other NDE
methods, should any nonconformities arise either during the qualification
program, or application of ANDE methods during normal testing
activities.
5.15.7 The procedure qualification shall be considered approved upon successful completion
of documentation and report review, data analysis, and witness of on-site
demonstration activities, as described in these Rules.
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