NB/T 47013.11-2015 English PDF (NB/T47013.11-2015)

NB/T 47013.11-2015: Nondestructive testing of pressure equipments - Part 11: Standard practice for X-ray digital radiography [Including 2018XG1]
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NB/T 47013.11-2015
ENERGY INDUSTRY STANDARD OF
THE PEOPLE’S 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’s 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 i...