Section 5 Non-destructive examination
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules for the Manufacture, Testing and Certification of Materials, July 2022 - Chapter 1 General Requirements - Section 5 Non-destructive examination

Section 5 Non-destructive examination

Parent topic: Chapter 1 General Requirements

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):
  1. a quality management system covering all necessary and relevant information and processes, enabling effective NDE operations;
  2. training and certification of NDE personnel;
  3. responsibilities of Supervisors and Operators;
  4. equipment
  5. procedures and work instructions;
  6. control and use of sub-contractors (as applicable); and
  7. 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:
  1. organisation and management structure, including any subsidiaries;
  2. quality management system;
  3. procedures and work instructions;
  4. details of training requirements, and Written Practice (if applicable) according to SNT-TC-1A;
  5. roles and responsibilities of supervising and practitioner personnel;
  6. company experience;
  7. equipment controls, including guidelines for use of equipment; and
  8. customer feedback, relevant complaints, and any legal proceedings against the company (historical or present); and
  9. 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:
  1. Training and certification processes, including visual acuity;
  2. Work procedures and instructions;
  3. Maintenance of documents, records and standards;
  4. Maintenance, control, and calibration of equipment;
  5. Processes for supervision and effective control of operations;
  6. Traceability of records and equipment;
  7. Code of conduct for activities;
  8. Corrective and preventive actions; and
  9. 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:

  1. 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.

  2. Procedures are to specify the qualification and certification requirements of the inspection personnel to be employed.

  3. Procedures are to state the degree of surface preparation required and the methods of preparation to be used before the examinations are made.

  4. Procedures are to state the reference standards for testing and the acceptance criteria to be applied to the results of the inspections.

  5. 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.

  6. Procedures are to identify any requirements for increasing the extent of applied NDE where defects have been found during spot examination.

  7. Procedures are to identify reporting requirements.

  8. Procedures are to be reviewed by the Surveyor to ensure that they are appropriate for the product type.

  9. Procedures are to include the method and requirements for equipment calibrations and functional checks.

  10. 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.

  11. 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:

  1. Date of test, and date of test report (if different from test).
  2. Name and qualification of Operator with signatures of the Operator.
  3. Details of the component identification, ship hull number (where applicable), description of test location, purpose of test and volume examined.
  4. Material type, grade, stage of manufacture (where applicable), product form, geometrical configuration, dimensions and thickness.
  5. Heat treatment status, where applicable.
  6. 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.
  7. Surface condition and surface test temperature.
  8. Test procedure, testing standards, and testing level (as applicable).
  9. Equipment used, including instrument manufacturer, type of instrument, and any identification numbers (as applicable).
  10. 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.
  11. Reference to acceptance criteria and evaluation in accordance with these criteria.
  12. Calibration details of the equipment and reference samples, as appropriate to the test method.
  13. Viewing conditions.
  14. Details of software used (where applicable).
  15. Method and values used for range and sensitivity settings (where applicable).
  16. Details of any signal processing and scan increment settings (where applicable).
  17. Access limitations and any deviations from standards or procedures.
  18. 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:

  1. Type of penetrant, cleaner, and developer used.
  2. Penetration and development timings.
  3. 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:

  1. Type of magnetisation.
  2. Magnetic field strength.
  3. Detection media.
  4. Viewing/lighting conditions.
  5. 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:

  1. Type and size of radiation source (width of radiation source), X-ray voltage.
  2. Type of film/designation and number of films in each film holder/cassette.
  3. Number of exposures or radiographs.
  4. Type of intensifying screens where applicable.
  5. Exposure technique, time of exposure and source to film distance.
  6. Distance from radiation source to weld.
  7. Distance from source side of the weld to the radiographic film.
  8. Approximate angle of radiation beam through the weld.
  9. Sensitivity, type and position of IQI.
  10. Optical density.
  11. Geometric un-sharpness.
  12. Specific acceptance class criteria for RT.
  13. 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:

  1. 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).
  2. Sensitivity levels calibrated and applied for each transducer.
  3. Amount of transfer loss correction applied and type of reference blocks used.
  4. Signal response used for defect detection.
  5. 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):
  1. 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).
  2. Any variation to applying the standard (e.g. IQI placement of standard or duplex wire IQI) shall be agreed with LR.
  3. 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.

5.12.5 The acceptance standard for steel welds shall be the same as for film radiography and is shown in Table 13.2.6 Acceptance criteria for radiographic testing. Further requirements for the examination of welds are specified in Ch 13, 2.12 Non-destructive examination of steel welds.

5.12.6 The acceptance standard for aluminium welds shall be the same as for film radiography and is shown in Table 13.8.3 Radiographic acceptance criteria for internal imperfections of aluminium. Further requirements for the examination of welds are specified in Ch 13, 2.12 Non-destructive examination of steel welds.

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:

  1. 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.
  2. Radiation source, type and size of focal spot and identification of equipment used.
  3. Detector, screens, filters (where applicable) and detector basic spatial resolution.
  4. Detector position plan, and source-to-detector distance.
  5. Tube voltage and current, or source type and activity, as applicable.
  6. Exposure duration.
  7. Type and position of image quality indicators (IQIs), including duplex wire IQIs.
  8. 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.
  9. For RT-S: type and parameters such as gain, frame time, frame number, pixel size, calibration procedure.
  10. For RT-CR: scanner type and parameters such as pixel size, scan speed, gain, laser intensity, laser spot size.
  11. Image processing parameters used, e.g. of the digital filters.
  12. Details of any software used, such as evaluation software, or defect simulation software (where applicable).
  13. 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:
  1. 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.
  2. 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)
  3. 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.
  4. 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):
  1. 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.
  2. 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.
  3. 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
  4. 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.
  5. The purpose of the testing and the volume to be inspected is to be defined in the testing procedure.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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:

  1. Manufacturer, type, frequency of phased array probes including number and size of elements, material and angle(s) of wedges, with identification numbers, where applicable.
  2. Details of reference block(s) with identification numbers, where applicable.
  3. Type of couplant used.
  4. Increment (E-scans), and/or angular increment (S-scans).
  5. Element pitch and gap dimensions.
  6. Focus (calibration should be the same as scanning).
  7. Virtual aperture size, i.e. number of elements and element width.
  8. Element numbers used for focal laws.
  9. Manufacturer documentation on the permitted wedge angular range.
  10. Documented calibration, TCG and angle gain compensation.
  11. Scan plan.
  12. 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.
  13. Reference points and details of the coordinate system.
  14. 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:
  1. 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.
  2. 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.
  3. 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.
  4. 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):
  1. 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).
  2. 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.
  3. 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.
  4. 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.
  5. The purpose of the testing and the volume to be inspected is to be defined in the testing procedure.
  6. 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.
  7. 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.
  8. Indications detected when applying the testing procedure are usually to be evaluated by length and height.
  9. 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.
  10. The sizing of indications is to be as per the requirements of ISO 10863, or recognised equivalent standards acceptable to LR.
  11. 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:

  1. Manufacturer, type, frequency, element size and beam angle(s) of probes, with identification numbers, where applicable.
  2. Details of reference block(s) with identification numbers, where applicable.
  3. Type of couplant used.
  4. Details of TOFD setups.
  5. Scan plan, and details of offset scans (if required).
  6. 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.
  7. Reference points and details of the coordinate system.
  8. 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:
  1. 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.
  2. The operating methodology and detailed extent of utilisation, including all product forms, thickness, and weld configurations (as applicable).
  3. 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):
  1. Review of available performance data for the inspection system (detection capability and defect sizing accuracy).
  2. Identification and evaluation of significant parameters, and their variability in determining accurate results.
  3. 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.
  4. Documentation of results from the test program, to demonstrate the effective repeatability and reliability of the ANDE method.
  5. 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.
  6. 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.
  7. 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.
  8. The onsite demonstration process shall be witnessed by LR.
  9. 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:
  1. Performance demonstration of the proposed ANDE method on the agreed test welds/test pieces/qualification blocks, as appropriate.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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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