NB/T 47013.14-2023 English PDF (NBT47013.14-2023)

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NB/T 47013.14-2023: Nondestructive testing of pressure equipments - Part 14: X-ray computed radiographic testing
NB/T 47013.14-2023
NB
ENERGY INDUSTRY STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.20
CCS H 26
Replacing NB/T 47013.14-2016
Nondestructive Testing of Pressure Equipment – Part 14:
Computed Radiographic Testing
ISSUED ON: OCTOBER 11, 2023
IMPLEMENTED ON: APRIL 11, 2024
Issued by: National Energy Administration
Table of Contents
Foreword ... 4
Introduction ... 7
1 Scope ... 8
2 Normative References ... 8
3 Terms and Definitions ... 9
4 General Requirements ... 12
5 Testing Process and Its Selection ... 18
6 Image Quality Requirements ... 30
7 Defect Identification and Measurement ... 36
8 Image Storage and Preservation ... 36
9 Evaluation of Inspection Results and Quality Grading ... 37
10 Testing Records and Reports ... 37
Appendix A (Informative) Test Method of Min. Grey Value ... 39
Appendix B (Normative) Determination of Resolution (Ratio) ... 41
Appendix C (Normative) Determination of Normalized Signal-to-Noise Ratio ... 44
Bibliography ... 45
Nondestructive Testing of Pressure Equipment – Part 14:
Computed Radiographic Testing
1 Scope
1.1 This Document specifies the radiographic computer-aided imaging inspection technology
and quality grading requirements for fusion welding joints of metal material pressure
components of pressure-bearing equipment. Metal materials used to make welding joints
include steel, copper and copper alloys, aluminum and aluminum alloys, titanium and titanium
alloys, nickel and nickel alloys.
1.2 This Document is applicable to the radiographic computer-aided imaging inspection of butt
welds of plates and tubes (hereinafter referred to as "butt welds") during the manufacture,
installation and in-service inspection of pressure components of pressure-bearing equipment.
1.3 The imaging device applicable to this Document is the imaging plate.
1.4 The radioactive source applicable to this Document is the X-ray source and the Ir192 and
Se75γ radioactive source, where the maximum tube voltage of the X-ray machine does not
exceed 600kV.
1.5 The radiographic computer-aided imaging inspection of welding joints of pressure-bearing
equipment supports and structural parts and plug-in and placement tubes can be used as a
reference.
2 Normative References
The provisions in following documents become the essential provisions of this Document
through reference in this Document. For the dated documents, only the versions with the dates
indicated are applicable to this Document; for the undated documents, only the latest version
(including all the amendments) is applicable to this Document.
GB/T 14058 Apparatus for gamma radiography
GB/T 21356 Non-destructive testing - Qualification and long-term stability of computed
radiology systems
GB/T 23901.1 Non-destructive testing - Image quality of radiographs - Part 1:
Determination of the image quality value using wire-type image quality indicators
spacing of the laser scanner scanning the imaging plate, and the ratio of the laser point scanning
speed to the operating frequency of the analog-to-digital converter.
3.16 Signal-to-noise ratio (SNR)
In a digital image, the ratio of the linearized grey mean to the standard deviation of a selected
area.
3.17 Normalized signal-to-noise ratio (SNRn)
Signal-to-noise ratio that is normalized based on resolution ratio.
3.18 Penetrated thickness (W)
The nominal thickness of the material in the direction of the ray penetration. In case of multi-
layer penetration, the penetrated thickness is the sum of the nominal thickness of each layer of
material.
3.19 Effective length of a single exposure
The maximum effective testing length of a single exposure is in accordance with the standard.
3.20 Ratio between max. and min. penetrated thicknesses (K)
The ratio of the maximum thickness and the minimum thickness of the parent material that the
radiation beam penetrates within an effective length of a single exposure is also called the ratio
between max. and min. penetrated thicknesses.
3.21 Digital image processing
Methods and techniques for processing digital images by computers.
3.22 Standard sample
A specimen of known size that is used to calibrate the size of features in an image.
3.23 Raw image
The image that is formed by the latent image on the imaging plate is scanned by a scanner.
3.24 Round flaw
Volume defects such as pores, slag inclusions and tungsten inclusions with an aspect ratio of
no more than 3.
3.25 Stripy flaw
Volume defects such as pores, slag inclusions and tungsten inclusions with an aspect ratio of
requirements. The system performance testing conditions and testing methods shall be
implemented in accordance with the provisions of GB/T 21356. The system shall at least meet
the following performance indicators:
a) The image geometric distortion rate shall be less than ±2%;
b) There shall be no jitter or sliding between the scanner and the imaging plate, or the jitter
shall be lower than the system noise level;
c) On the same horizontal line of the image, the grey change rate between the center area
and the edge background shall not exceed ±10%;
d) Other performance indicators include signal-to-noise ratio, laser beam function, shadow,
image erasure, artifacts, etc.
4.2.3.1 Imaging plate
The supplier shall provide the quality certification documents of the imaging plate, which shall
at least include the type and specifications, excitation response time, chemical composition and
other main performance parameters of the imaging plate. Users shall use and store it according
to the temperature and humidity conditions recommended by the manufacturer, and avoid
unnecessary exposure.
4.2.3.2 Scanner
The supplier shall provide the quality certification documents of the scanner, which shall at
least include the specifications, scanning size, photomultiplier tube voltage or gain, scanning
resolution ratio, laser beam focus size and other main performance parameters; and its functions
and performance shall at least meet the following requirements:
a) The scanner shall have the scanning and erasing functions, and the residual latent image
grey value after erasing shall not exceed 5% of the maximum greyscale of the system;
b) The scanning laser power shall meet the requirements of signal acquisition;
c) The photomultiplier tube voltage or gain and scanning resolution ratio of the scanner shall
be adjustable;
d) The laser beam shall be free of vibration, and there shall be no artifacts or scanning line
loss.
4.2.4 Computer system
The basic configuration of the computer system is determined according to the performance
and scanning speed requirements of the adopted CR system. It should be equipped with a
memory of no less than 512MB, a hard disk of no less than 40GB, a high-brightness and high-
resolution ratio display, a CD writer, a network card, etc.
The display shall meet the following minimum requirements:
a) Minimum brightness of 250 cd/m2;
b) The display has at least 256 grey levels;
c) The minimum displayable light intensity ratio is 1:250;
d) The display has at least 1M pixels and the pixel size is less than 0.3 mm.
4.2.5 System-specific software
4.2.5.1 The system software is the core unit of the computed radiographic testing system, which
controls the scanner to complete the conversion of the imaging plate acquisition information to
the digital image, as well as the functions of latent image erasure, image storage, auxiliary ...