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NB/T 47013.11-2015 English PDF (NBT47013.11-2015)

NB/T 47013.11-2015 English PDF (NBT47013.11-2015)

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NB/T 47013.11-2015: Nondestructive testing of pressure equipments - Part 11: Standard practice for X-ray digital radiography [Including 2018XG1]

This Part of NB/T 47013 specifies the X-ray digital radiographic testing technology and quality grading requirements of fusion welded joints for metal pressure parts of pressure equipment.
NB/T 47013.11-2015
ENERGY INDUSTRY STANDARD OF
THE PEOPLE REPUBLIC OF CHINA
ICS 77.040.20
H 26
Nondestructive testing of pressure equipment -
Part 11: Standard practice for X-ray digital radiography
[Including Modification 2018XG1]
ISSUED ON: APRIL 2, 2015
IMPLEMENTED ON: SEPTEMBER 1, 2015
Issued by: National Energy Administration
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 General requirements ... 8
5 Testing methods ... 12
6 Image quality and evaluation ... 18
7 Testing result assessment and quality grading (acceptance) ... 27
8 Image preservation and storage ... 27
9 Testing records and reports ... 27
Annex A (Normative) Verification method of the system resolution ratio ... 29 Annex B (Informative) Typical trans-illumination modes ... 31
Annex C (Normative) Recognition of the image quality indicator (duplex wire type) ... 34
Annex D (Normative) Normalized SNR test method ... 36
Annex E (Informative) Format of the testing report ... 37
Modification Notification of Industry Standard NB/T 47013.11-2015 (2018XG1) ... 39
Foreword
This Standard NB/T 47013 Nondestructive testing of pressure equipment is divided into the following 13 parts:
?€? Part 1: General requirements;
?€? Part 2: Radiographic testing;
?€? Part 3: Ultrasonic testing;
?€? Part 4: Magnetic particle testing;
?€? Part 5: Penetrant testing;
?€? Part 6: Eddy current testing;
?€? Part 7: Visual examination;
?€? Part 8: Leak testing;
?€? Part 9: Acoustic emission testing;
?€? Part 10: Ultrasonic time of flight diffraction technique;
?€? Part 11: Standard practice for X-ray digital radiography;
?€? Part 12: Magnetic flux leakage testing;
?€? Part 13: Pulsed eddy current testing.
This Part is Part 11 of NB/T 47013: Standard practice for X-ray digital radiography.
This Part was drafted in accordance with the provisions given in GB/T 1.1-2009 Directives for standardization - Part 1: Structure and drafting of standards. This Standard was proposed by and shall be under the jurisdiction of the National Technical Committee for Standardization of Boiler and Pressure Vessels (SAC/TC 262).
Drafting organizations of this Part: China Special Equipment Inspection and Research Institute, Guangdong Yingquan Steel Products Co., Ltd, Special Equipment Safety Supervision Inspection Institute of Jiangsu Province, Special Equipment Safety Supervision Bureau of General Administration of Quality Supervision Inspection and Quarantine of the PEOPLE Republic of China, North University of China, Beihang University, Sichuan Ruidi X-ray Digital Imaging Technology Co., Ltd, National X-ray Digital Imaging Instrument Center, Sichuan Chuanguo Boiler Co., Ltd, Beijing Jiasheng Guoan Technology Co., Ltd, and Chengdu Huayu Inspection Technology Co., Ltd.
Main drafters of this Part: Liang Lihong, Lin Shuqing, Ding Keqin, Zeng Xiangzhao, Qiang Tianpeng, Zheng Hui, Chen Guang, Wang Xiaomei, Xiu
Changzheng, Han Yan, Fu Jian, Xiang Qian, Chen Hao, Yan Chunsong, Shuai Jiasheng, and Tang Liangming.
This Part is first formulated.
Nondestructive testing of pressure equipment - Part
11: Standard practice for X-ray digital radiography
1 Scope
1.1 This Part of NB/T 47013 specifies the X-ray digital radiographic testing technology and quality grading requirements of fusion welded joints for metal pressure parts of pressure equipment.
1.2 This Part is applicable to the manufacturing and installation of pressure parts of pressure equipment as well as the X-ray digital radiographic testing of welded joints in testing. For the metal materials used to make welded joints, including steel, copper and its alloys, aluminum and its alloys, iron and its alloys, nickel and its alloys, this Part shall also apply.
1.3 A digital detector shall be used as the imaging device in this Part. The applicable X-ray machine shall have a maximum tube voltage of not exceeding 600kV.
1.4 For the X-ray digital radiographic testing of welded joints for relevant supporting members and structural members of pressure equipment, this Part may be used for reference.
2 Normative references
The following documents are essential to the application of this document. For dated references, only the editions with the dates indicated are applicable to this document. For undated references, only the latest editions (including all the amendments) are applicable to this document.
GB 18871 Basic standards for protection against ionizing radiation and for the safety of radiation sources
GB/T 23901.1 Non-destructive testing - Image quality of radiographs - Part 1: Image quality indicators (wire type) - Determination of image quality value GB/T 23901.5 Non-destructive testing - Image quality of radiographs - Part 5: Image quality indicators (duplex wire type) - Determination of image unsharpness value
GB/T 23903 Resolution indicators for ray image
GBZ 117 Radiological protection standards for industrial X-ray detection NB/T 47013.1 Nondestructive testing of pressure equipment - Part 1:
General requirements
NB/T 47013.2 Nondestructive testing of pressure equipment - Part 2:
Radiographic testing
3 Terms and definitions
For the purposes of this Part, the terms and definitions defined in NB/T 47013.1 and the following ones apply.
3.1 Pixel
Basic components of X-ray digital images. X-ray digital images are made up of dots. Each dot that makes up an image is called a pixel.
3.2 Image sensitivity
The ability of the testing system to discover the smallest details in the image of the tested object.
3.3 Resolution ratio
The ability of distinguishing the minimum distance between two adjacent details per unit length, expressed in 1p/mm.
3.4 Resolution
Resolution capability of the minimum distance between two adjacent details. 3.5 System resolution ratio
The ability of the testing system to distinguish the minimum distance between two adjacent details per unit length, when the geometric magnification of trans- illumination is close to 1, in the absence of a tested object, reflecting the characteristics of the testing system itself, also known as the system?€?s basic spatial resolution ratio.
3.6 Image resolution ratio
The ability of the testing system to distinguish the minimum distance between two adjacent details per unit length in the image of the tested object, also known as the image?€?s spatial resolution ratio.
3.7 Digital detector
An electronic device that converts X-ray photons into digital signals, hereinafter referred to as the detector.
3.8 Gray level
A quantitative description of the brightness of a black-and-white image obtained by an X-ray digital radiography system, which is determined by the number of bits in the system?€?s A/D converter (analog-to-digital converter). The higher the bits of the A/D converter, the higher the gray level. For instance, in the case of a 12-bit A/D converter, the gray level acquired is 212 = 4 096.
3.9 Dark image
An image that is output in the absence of X-ray trans-illumination, also known as the dark current image.
3.10 Dynamic range
The ratio of the maximum gray level of the X-ray digital radiography system to the standard deviation of the dark image within the linear output range. 3.11 Non-uniform responsivity
The inherent characteristics of the detector. The output image brightness is presented with non-uniform fringe due to the inconsistent response of the detector to the X-rays, under the condition of uniform trans-illumination of homogeneous objects or blank screen.
3.12 Bad pixel
The occurrence of white or black dots in a dark image that are either much higher or much lower than the gray level of an adjacent pixel, also referred to the situation that the output value of the corrected image is far away from the outlier of the image mean. Bad pixels exist in the form of a single point, two adjacent points and multiple adjacent points, a few rows or a few columns. 3.13 Signal noise ratio (SNR)
The ratio of the mean value of the signal to the standard deviation of the signal in the ROI image.
3.14 Static imaging
X-ray digital radiography when there is no relative continuous motion between the testing system and the tested object. The imaging results are presented in a single image.
3.15 Dynamic imaging
X-ray digital radiography when there is relative continuous motion between the testing system and the tested object. The imaging results are presented in a sequential image.
3.16 Limiting resolution
The maximum resolution of the testing system, in the absence of physical (geometric) amplification.
3.17 Digital image processing
Digital transformation method for improving the contrast, resolution ratio and detail recognition capability of X-ray digital radiography.
3.18 Non-planar object
Other objects described in this Part except for the planar object.
4 General requirements
4.1 Testing personnel
4.1.1 Personnel engaged in X-ray digital radiographic testing shall receive the training on radiation safety knowledge prior to work, and obtain the Radiologic Worker Certificate.
4.1.2 Personnel engaged in X-ray digital radiographic testing shall obtain the special qualification for X-ray digital radiography in nondestructive testing of special equipment, before testing the corresponding items.
4.1.3 Testing personnel shall understand the computer and digital image processing knowledge related to the X-ray digital radiography, and shall master basic computer operation methods accordingly.
4.2 Testing system
4.2.1 X-ray machine
4.2.1.1 The energy range of the X-ray machine shall be selected based on the thickness and material of the tested object as well as the focal length. 4.2.1.2 The selected focus shall match the detector in use.
4.2.2 Detector system
4.2.2.1 It includes the planar array detector, linear array detector and their accessories.
4.2.2.2 The dynamic range shall not be less than 2 000: 1.
4.2.2.3 The bits of the A/D converter shall not be less than 12bit.
4.2.2.4 The detector supplier shall provide the bad pixel table and bad pixel correction method along with the detectors.
4.2.2.5 The detectors shall be corrected in accordance with the specific image correction method specified by the detector system.
4.2.3 Computer system
The basic configurations of the computer system shall be determined according to the performance and speed requirements of the X-ray digital radiographic components. The computer system should be equipped with a RAM of not less than 512MB, a hard drive of not less than 40GB, a high-brightness high- resolution display, a recorder, a network card, etc.
The display shall meet the following minimum requirements:
a) Brightness shall not be less than 250cd/m2;
b) Gray level shall not be less than 8bit;
c) Image display resolution shall not be less than 1 024 ?? 768;
d) The display?€?s pixel pitch shall not be greater than 0.3mm.
4.2.4 System software requirements
4.2.4.1 The system software is the core unit of the X-ray digital radiography system, with the functions such as image acquisition, image processing, defect geometric dimension measurement, defect marking, image storage, auxiliary evaluation, testing report printing and other auxiliary functions, which is an important factor to ensure the testing accuracy and safety.
4.2.4.2 It shall include basic digital image processing functions such as superimposed noise reduction, adjustment of window width and window level, contrast enhancement, etc.
4.2.4.3 It shall include such functions as SNR measurement, defect marking, size measurement and size calibration.
4.2.4.4 It should have a magnification of not less than 4 times.
4.2.4.5 It shall be able to browse and search the relevant information of the acquired images.
4.2.4.6 The test report may be generated according to the evaluation results. 4.2.4.7 The original images shall be stored. It is allowed to process
accordingly during observation and evaluation.
4.2.4.8 Smoothing and other means of image processing of the original
images shall be agreed upon by both parties and recorded in the relevant documents.
4.2.4.9 Other special requirements shall be determined through consultation by both parties.
4.2.5 Testing tooling
4.2.5.1 It shall be designed according to the tested object and meet the testing requirements.
4.2.5.2 The carrying capacity of the testing tooling shall be selected according to the weight of the tested object.
4.2.5.3 It should have such functions as translation, rotation, continuous adjustable speed, etc., and shall ensure high operating accuracy and stability. 4.2.5.4 The motion of the testing tooling shall be synchronized with the data acquisition of the detector.
4.2.5.5 For the testing of in-service equipment, the testing instruments and equipment shall be fixed in a reasonable manner according to the site
environment and testing conditions.
4.2.6 Acceptance and verification of the testing system
4.2.6.1 The performance test certificates of the testing system shall be provided. Prior to the first use, the testing system shall be conducted with performance acceptance. It may be used only after acceptance.
4.2.6.2 Verification shall be carried out in the following cases. Verification mainly refers to the testing of system resolution ratio. The verification method shall be in accordance with Annex A.
a) when there is a change in the testing system;
b) under normal operating conditions, it shall be verified at least once every three months;
c) when the system is reused one month after it is out of use.
4.3 Testing technology levels
The levels of X-ray testing technology specified in this Part are divided as follows: Level AB - medium-sensitivity technology; Level B - high-sensitivity technology.
4.4 Testing process documents
4.4.1 The testing process documents include the process procedures and
operating instructions.
4.4.2 The contents of the process procedures shall meet not only the
requirements of NB/T 47013.1, but also the specific range or requirements of relevant factors listed in Table 1. In the event of changes in relevant factors beyond the requirements, the process procedures shall be re-prepared or revised.
Table 1 -- Relevant factors involved in the process procedures
Serial No. Relevant factors
1 Type and specifications (shape, size, wall thickness and material) of the tested object 2 Pursuant regulations and standards
3 Testing equipment and calibration, verification, operational verification or inspection requirements 4 Testing process (trans-illumination modes, trans-illumination parameters, geometric parameters, motion parameters, etc.) 5 Testing technologies
6 Process test report
7 Defect evaluation and quality grading
4.4.3 The operating instructions shall be prepared according to the contents of the process procedures and the testing requirements of the tested object. The contents shall not only meet the requirements of NB/T 47013.1, but also include:
a) testing technology levels;
b) testing equipment [including the X-ray machine (specifications), detector (specifications), filter board, image quality indicator, marks, testing tooling, computer, display, system software, etc.];
c) testing process parameters (including the tube voltage, exposure,
geometric parameters of trans-illumination, material and thickness of the filter board, relative position of the testing equipment and the testing area, motion form and speed of the tested object, trans-illumination modes, etc.); d) requirements for the testing identification;
e) operating procedures of testing;
f) testing records;
g) image evaluation (including the gray level, signal noise ratio, image resolution ratio, image sensitivity, marks, etc.);
h) testing quality rating.
4.4.4 Process verification of the operating instructions
4.4.4.1 The operating instructions shall be conducted with process verification prior to the first application.
4.4.4.2 The verification modes may be carried out by using an image quality indicator, simulation test block or actual testing object.
4.4.4.3 Verification may be carried out through a special trans-illumination test, or may use the first batch of images of the product as a basis for verification. In both cases, the verification images to be based shall be identified.
4.5 Safety requirements
4.5.1 The testing environment shall meet the requirements of system
operation for the environment (temperature, humidity, grounding,
electromagnetic radiation, vibration, etc.).
4.5.2 The X-ray radiation protection conditions shall meet the relevant requirements of GB 18871 and GBZ 117.
4.5.3 In the case of X-ray digital radiographic testing on the site, the control area and the management area shall be delineated in accordance with the requirements of GBZ 117. The warning signs shall be set as well. The testing personnel shall wear a personal dosimeter and carry a dose alarm device. 5 Testing methods
5.1 Trans-illumination modes
5.1.1 Appropriate trans-illumination modes shall be selected according to the structural characteristics of the tested object and the requirements for technical conditions. GIVE priority to the single-wall trans-illumination mode. Double-wall trans-illumination mode is allowed only when the single-wall trans-illumination cannot be carried out. REFER to Annex B for typical trans-illumination modes. 5.1.2 When dynamic imaging mode is used for image acquisition, the motion speed of the tested object shall be matched with the frame frequency of image acquisition. Meanwhile, it is necessary to ensure that the X-ray main beam trans-illuminates the tested object vertically (or in alignment) and reaches the effective imaging area of the detector.
5.1.3 In the case of image acquisition by static imaging, the length of overlapped area of image acquisition shall not be less than 10mm.
5.1.4 Small-diameter tubes shall be arranged in double-wall double-shadow trans-illumination mode. When the following conditions are met at the same time, the oblique trans-illumination mode shall be used for elliptical imaging: a) T (wall thickness) ??? 8mm;
b) g (weld width) ??? Do / 4.
Where: Do - Outer diameter of the tube.
The opening width (the maximum distance between the upper and lower weld projections) of the images shall be controlled at about 1 times the weld width. In the case of failing to meet the above conditions or elliptical imaging difficulties, vertical trans-illumination mode may be used for overlapping imaging.
5.2 Selection of imaging geometric parameters
5.2.1 The distance from the selected X-ray machine to the surface of the tested object, f, shall meet the following requirements:
a) Level AB X-ray digital radiographic testing technology: f ??? 10d?€?b2/3; b) Level B X-ray digital radiographic testing technology: f ??? 15d?€?b2/3. The diagram of imaging geometric trans-illumination is described in Figure 1. The effective focus size, d, shall be calculated in accordance with the relevant requirements of NB/T 47013.2. b represents the distance from the surface of the tested object to the detector.
Explanation:
1 - Detector;
2 - Tested object.
Figure 1 -- Diagram of imaging geometric trans-illumination
5.2.2 In the ev...

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