标准编号:	NB/T 47013.14-2016
中文名称:	承压设备无损检测 第14部分：X射线计算机辅助成像检测
英文名称:	Nondestructive testing of pressure equipments Part 14: X-ray Computed radiographic testing
行业分类:	NB    能源行业标准
发布机构:	国家能源局
发布日期:	2016-08-16
实施日期:	2016-12-1
标准状态:	被替代
被新标准替代:	NB/T 47013.14-2023 承压设备无损检测 第14部分：射线计算机辅助成像检测
被替代日期:	2024-4-11
翻译语言:	英文
文件格式:	PDF
中文字符数:	21000 字
翻译价格(元):	1020.00 元
交付时间:	付款后 1 个工作日

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.



NB/T 47013 consists of the following fourteen parts under the general title Nondestructive testing of pressure equipment:



——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;



——Part 14: X-ray computed radiographic testing.



This is Part 14 X-ray computed radiographic testing of NB/T 47013.



This standard is developed in accordance with the rules given in GB/T 1.1-2009 Directives for standardization - Part 1: Structure and drafting of standards.



This part was proposed by and is under the jurisdiction of the National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).



This part is issued for the first time.





Nondestructive testing of pressure equipment - Part 14: X-ray computed radiographic testing



1 Scope



1.1 This part of NB/T 47013 specifies the technical and quality classification requirements for fusion welded joints of metal pressure parts of pressure equipment subjected to 450kV and below X-ray computed radiographic testing (hereinafter referred to as CR testing).



1.2 This part is applicable to CR testing of fusion welded joints of steel, copper and copper alloy, aluminum and aluminum alloy, titanium and titanium alloy, nickel and nickel alloy materials. The type of welded joint is butt weld of butt joint of plate or pipe (hereinafter referred to as "butt weld").



1.3 This part may also serve as a reference for CR testing on welded joint of other materials, supporting members and structural members of the pressure equipment.



2 Normative references



The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.



GB 11533 Standard for logarithmic visual acuity charts

GB/T 12604.2 Non-destructive testing - Terminology - Terms used in radiographic testing

GB 18871 Basic standards for protection against ionizing radiation and for the safety of radiation sources

GB/T 21356 Non-destructive testing - Qualification and long-term stability of computed radiology systems

GB/T 23901.5 Non-destructive testing - Image quality of radiographs - Part 5: Image quality indicators (duplex wire type) - Determination of image unsharpness value

GBZ 117 Radiological protection standards for industrial X-ray detection

JB/T 5075 Non-destructive testing - Metal intensifying screens for radiographic testing

JB/T 7902 Non-destructive testing - Image quality indicators (wire type) for radiographic testing

NB/T 47013.1 Nondestructive testing of pressure equipment - Part 1: General requirements

NB/T 47013.2-2015 Nondestructive testing of pressure equipment - Part 2: Radiographic testing

3 Terms and definitions



For the purposes of this document, the terms and definitions given in GB/T 12604.2, NB/T 47013.1 and NB/T 47013.2 and the following apply.



3.1

imaging plate, IP

flexible board coated with photo-excited phosphorescent crystal and capable of storing information in the form of latent image after exposure and replacing film for radiography testing



3.2

X-ray computed radiography system, CRS

system consisting of IP, special laser scanner, computer hardware and special software, etc. and capable of converting the information on IP into digital images, which is referred to as "CR system"



3.3

object-to-IP distance, b

distance between the surface of the tested object (at the side of the radiation source) and the IP measured in the direction of the radiation beam



3.4

source-to-IP distance, F

distance between the radiation source and the IP measured in the direction of the radiation beam, i.e. the focal distance



3.5

source-to-object distance, f

distance between the radiation source and the surface of the tested object (at the side of radiation source) measured along the centerline of the radiation beam



3.6

contrast sensitivity, CS

sensitivity represented by gray difference of digital image caused by radiography thickness difference, which is generally expressed by line diameter or line diameter number of image quality indicator (wire type)



3.7

structure noise of IP

intrinsic noise of digital image caused by uneven structure of photosensitive layer and IP surface



 

3.8

grey level, GL

quantitative description for the brightness degree of black and white images, which is determined according to the number of bits of the system A/D converter (analog-to-digital converter). The higher of the number of bits of A/D converter, the higher of the grey level. For example, when the A/D converter is 12bit, the collected grey level is 212＝4 096



3.9

pixel

basic component units of an X-ray digital image. A X-ray digital image is composed of dots which are referred to as pixels



3.10

grey value, GV

value representing the brightness degree of pixels in a digital image



3.11

linearized grey value, GVlin

grey value proportional to the exposure of IP



3.12

basic spatial resolution of a CR system, SRb

ability of the digital image of a CR system to display the minimum details per unit length obtained according to standard test conditions when there is no tested object, which is referred to as "resolution of a CR system”



3.13

spatial resolution of a digital image, SRbi

ability of the digital image to display the minimum details per unit length obtained according to actual testing conditions when there is tested object, which is referred to as "resolution of a digital image”



3.14

signal-to-noise ratio, SNR

ratio of the average grey value to the standard deviation of the selected area in a digital image



3.15

normalized signal-to-noise ratio, SNRN

signal-to-noise ratio after normalization based on the resolution of a CR system SRb



3.16

effective length of a single exposure, Leff

effective testing length of a single exposure in conformity with the standard



3.17

scanning resolution

pixel geometry size of digital image determined by scanning, which depends on the line spacing of IP scanned by laser scanner and the ratio of the laser point scanning travel speed to the working frequency of analog-to-digital converter



3.18

digital image processing

methods and techniques of processing digital images by computer. Common processing methods of CR digital images include enlargement, reduction, grey scale transformation, contrast transformation and so on



4 General requirements



4.1 Testing personnel



4.1.1 Personnel engaged in CR testing shall meet the relevant requirements of NB/T 47013.1.



4.1.2 CR testing personnel shall be subjected to training on radiation safety knowledge, special CR theory and practical operation before taking up their posts, and obtain corresponding qualifications.



4.1.3 The uncorrected and corrected near vision and distant vision of CR testing personnel shall not be less than 5.0 (decimal record value is 1.0) and the testing method shall meet the requirements of GB 11533. Personnel engaged in the evaluation of digital images shall be subjected to an eye test once a year.



4.2 Testing equipment and apparatus



4.2.1 Radiation source



X-ray machines with focus size, tube voltage range and rated power suitable for the tested objects and meeting the technical requirements shall be selected.



4.2.2 CR system



The appropriate CR system shall be selected based on the tested object and technical requirements. System performance testing conditions and methods shall be in accordance with the requirements of GB/T 21356. The system shall at least meet the following performance indexes:



 

a) the image geometric distortion shall be less than ±2%;



b) there shall be no jitter or slippage between the scanner and the imaging plate (IP), or the jitter shall be lower than the system’s noise level;



c) on the same horizontal line of the image, the background grey of the central area and the edge shall not exceed ±10%;



d) other performance indexes include: signal-to-noise ratio, laser beam function, shadow, image erasure, artifacts, and so on.



4.2.2.1 Imaging plate (IP)



The IP quality certificate shall include at least the main performance parameters such as IP type and specification, dynamic range, excitation response time, and chemical composition. Users shall use and preserve the IP under the temperature and humidity conditions recommended by manufacturers and avoid unnecessary radiation. For the less-thick tested objects, IP with slower ISO speed shall be selected, and for thick tested objects, IP with faster ISO speed may be selected.



4.2.2.2 Scanner



The quality certificate of the laser scanner shall include at least the main performance parameters such as specification, scan size, input voltage, scanning resolution, laser beam focus size, scanning step speed, etc., and its functions and performance shall meet at least the following requirements:



a) the scanner shall have scanning and erasing function, and the grey value of the residual latent image after erasing shall not be higher than 5% of the maximum grey value of the system;



b) the scanning laser power shall meet the requirements of signal acquisition;



c) the photomultiplier voltage or gain, and the scanning resolution of the scanner shall be adjustable;



d) the laser beam shall be free of vibration and such phenomena as artifact or scan line loss.



4.2.2.3 Display



It shall meet the following requirements:



a) the minimum brightness shall be 250cd/m2;



b) the grey level of the displayer shall be at least level 256;



c) the minimum light intensity ratio that can be displayed shall be 1:250;



d) it shall display at least 1M pixel with a pixel size less than 0.3mm.



4.2.2.4 System specific software



It shall at least cover the following functions:



a) measurement functions: including grey scale measurement, spatial resolution measurement, measurement of signal-to-noise ratio, measurement of signal-to-noise ratio, etc.;



b) adjustment functions: including gray scale transformation, contrast adjustment, image scaling, etc.;



c) marking function.



4.2.3 Image quality indicator (IQI)



4.2.3.1 IQI (wire type)



a) The IQI (wire type), which is used to determine the contrast sensitivity of digital images, is classified into general-purpose IQI and equal-diameter IQI, of which the model and specification shall meet the requirements of JB/T 7902.



b) The range of tested object materials, which are applicable to the material code and material of IQI (wire type) as well as Indicator (wire type) made of different materials, may be in accordance with those specified in Table 1; the absorption coefficient of the materials of IQI (wire type) shall be close to or identical with the absorption coefficient of the materials under test as much as possible and shall not be higher than the absorption coefficient of the materials under test in any case.



Table 1 Range of materials applicable to IQI (wire type) made of different materials

Material code of

IQI (wire type) Al Ti Fe Ni Cu

Material of IQI (wire type) Commercially pure aluminum Commercially pure titanium Carbon steel Nickel-chromium alloy 3# pure copper

Range of applicable materials Aluminum and aluminum alloy Titanium and titanium alloy Steel Nickel and nickel alloy Copper and copper alloy



 

4.2.3.2 IQI (duplex wire type)



a) The IQI (duplex wire type) is used to measure CR system resolution and digital image resolution.



b) The model and specification of IQI (duplex wire type) shall meet the requirements of GB/T 23901.5.



4.2.4 The functions and performance of the testing equipment and apparatus shall meet the requirements above and corresponding supporting documents shall be provided.



4.2.5 Calibration or operation verification



4.2.5.1 Geometric distortion, jitter, uniformity, laser beam function, shadow, artifact, etc. among the performance of the CR system shall be calibrated or checked at least once a year and recorded.



4.2.5.2 The in-service exposure curve shall be verified at least once every year. The exposure curve shall be redrawn in the case any important component of the X-ray machine is replaced or repaired.



4.2.5.3 Operation verification



The CR system shall be checked and recorded in the following cases. Refer to GB/T 21356 for the checking method :



a) in the case of system changes (including repair and replacement of each component as well as software upgrade, etc.);



b) where the system is reused after shutdown for over 3 months;



c) under normal use conditions, the user can specify the verification frequency in the process documents according to the product specifications and use frequency, and implement verification according to the regulations.



4.3 Testing technology level



4.3.1 The CR testing technology is classified into three grades: Grade A - low sensitivity technology; Grade AB - intermediate sensitivity technology; and Grade B - high sensitivity technology.



4.3.2 The grade selection for CR testing technology shall meet the requirements of relevant regulations, standards and design technical documents and meanwhile shall also meet other technical requirements agreed between the contracting parties. As for the butt weld of pressure equipment, it is recommended to adopt Grade AB testing technology in general. As for butt welds of important equipment and structures, as well as those with special materials and special welding process, Grade B testing technology may be adopted.



4.3.3 In case that certain testing conditions fail to meet the requirements of Grade AB (or Grade B) testing technology, as agreed between contracting parties, and under the premise that effective remedy measures (e.g. increase the exposure or adopt a system with higher signal-to-noise ratio) are taken, if the digital image quality meets the requirements of Grade AB (or Grade B) testing technology, then it can be considered that testing has been conducted in accordance with Grade AB (or Grade B) testing technology.



4.3.4 If the source-to-object distance f does not meet the requirements of 5.7, the provisions of 4.3.3 shall not apply.



4.3.5 In case that certain testing conditions fail to meet the requirements of Grade AB testing technology in the CR testing of in-service pressure equipment, as agreed between contracting parties, and under the premise that effective remedy measures (e.g. increase the exposure or adopt a system with higher signal-to-noise ratio) are taken, the Grade A testing technology may be adopted for testing, while other non-destructive testing methods shall also be adopted for supplementary testing.



4.4 Testing process documents



4.4.1 The testing process documents include process procedure and operating instructions.



4.4.2 In addition to meeting the requirements of NB/T 47013.1, the process procedure shall also specify the specific scope or requirements of the following related factors. If the changes of related factors exceed the provisions, the process regulations shall be re-compiled or revised:



a) applicable structure, material category and thickness;



b) energy range and focus size of the radiation source;



c) testing technology grade;



d) radiography mode;



e) IP type and model;



f) model of IQI (wire type) and IQI (duplex wire type);



g) type and thickness of metal screen;



h) model and parameter setting of scanner;



i) digital image displayer.



4.4.3 The operating instructions shall be prepared according to the process procedure and the testing requirements for the tested object. Its content not only shall meet the requirements of NB/T 47013.1, but also shall at least include:



a) testing equipment and apparatus: radiation source (focus size), IP, metal screen (type and thickness), IQI (type and model), backscattering shield lead plate, mark, scanner and observation equipment, etc.;



b) testing technology and process: the grade of testing technology used, radiography mode (relative position between the radiation source and the tested object and IP), parameter selection (radiation source, IP, exposure conditions), IQI and mark type and arrangement, etc.;



c) parameters of the scanner;



d) image processing technology;



e) digital image quality requirements: resolution, contrast sensitivity, normalized signal-to-noise ratio, mark, etc.;



f) acceptance criteria;



g) verification requirements for operating instructions.



4.4.4 Initially used operating instructions shall be subject to process verification so as to verify whether the digital image quality can meet the requirements specified in the standard. Verification may be conducted via special radiography test or the first batch of digital images of the product may be taken as the verification basis. The digital images verified shall be marked.

Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Testing process and its selection
6 Testing result evaluation and quality grading
7 Testing record and report
Annex A (Informative) Testing method for the minimum grey value
Annex B (Normative) Determination of spatial resolution
Annex C (Normative) Determination of normalized signal-to-noise ratio

承压设备无损检测
第14部分：X射线计算机辅助成像检测
1 范围
1.1 NB/T 47013的本部分规定了承压设备金属材料受压元件的熔化焊焊接接头采用450kV以下X射线计算机辅助成像检测(以下简称“CR检测”)技术和质量分级要求。
1.2本部分适用于钢、铜及铜合金、铝及铝合金、钛及钛合金、镍及镍合金材料熔化焊焊接接头的CR检测。焊接接头的型式为板或管的对接接头对接焊缝(以下简称“对接焊缝”)。
1.3承压设备其他材料、支承件和结构件的焊接接头的CR检测，可参照使用。
2规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。
GB 11533 标准对数视力表
GB/T 12604.2 无损检测 术语 射线照相检测
GB 18871 电离辐射防护及辐射源安全基本标准
GB/T 21356 无损检测 计算机射线照相系统的长期稳定性与鉴定方法
GB/T 23901.5 无损检测 射线照相底片像质 第5部分：双线型像质计图像不清晰度的测定
GBZ 117 工业X射线探伤放射卫生防护标准
JB/T 5075 无损检测射线照相检测用金属增感屏
JB/T 7902 射线照相用线型像质计
NB/T 47013.1 承压设备无损检测 第1部分：通用要求
NB/T 47013.2—2015承压设备无损检测 第2部分：射线检测
3术语和定义
GB/T 12604.2、NB/T 47013.1和NB/T 47013.2界定的以及下列术语和定义适用于本文件。
3.1
成像板IP imaging plate
一种涂有光致激发磷光晶体的柔性板，曝光后能以潜影形式储存信息，可以代替胶片用于射线照相检测。
3.2
X射线计算机辅助成像系统CRS X-ray computed radiography system
由IP、专用激光扫描仪、计算机硬件和专用软件等组成，能将IP上的信息转换成数字图像的系统，简称“CR系统”。
3.3
被检工件至IP距离b object-to-IP distance
沿射线束中心线方向上测量的被检工件表面(射线源侧)至IP之间的距离。
3.4
射线源至IP距离F source-to-IP distance
沿射线束中心线方向上测量的射线源至IP之间的距离，即焦距。
3.5
射线源至被检工件距离f source-to-object distance
沿射线束中心线方向上测量的射线源至被检工件表面(射线源侧)之间的距离。
3.6
对比灵敏度CS contrast sensitivity
由透照厚度差造成数字图像灰度差所表征的灵敏度，一般用线型像质计的线径或线径编号表示。
3.7
IP的结构噪声 structure noise of IP
由感光层和IP表面的结构不均匀导致的数字图像的固有噪声。
3.8
灰度等级GL grey level
对黑白数字图像明暗程度的定量描述，它由系统A/D转换器(模/数转换器)的位数决定。A/D转换器的位数越高，灰度等级越高。例如，A/D转换器为12bit时，采集的灰度等级为212＝4 096。
3.9
像素pixel
X射线数字图像的基本组成单元。X射线数字图像由点组成，组成图像的点称为像素。
3.10
灰度值GV grey value
表征数字图像中像素明暗程度的数值。
3.11
线性灰度值GVlin linearized grey value
与IP的曝光量成正比的灰度值。
3.12
CR系统的基本空间分辨率SRb basic spatial resolution of a CR system
在无被检工件情况下，按照标准测试条件获得的、单位长度上CR系统数字图像所能显示的最小细节的能力，简称“CR系统分辨率”。
3.13
数字图像的空间分辨率SRbi spatial resolution of a digital image
在有被检工件情况下，按照实际检测条件得到的、单位长度上数字图像所能显示的最小细节的能力，简称“数字图像分辨率”。
3.14
信噪比SNR signal-to-noise ratio
在数字图像中，选定区域的灰度平均值与标准差的比值。
3.15
归一化信噪比SNRN normalized signal-to-noise ratio
基于CR系统分辨率SRb，经归一化处理后的信噪比。
3.16
一次透照长度Leff effective length of a single exposure
符合标准规定的单次曝光有效检测长度。
3.17
扫描分辨率scanning resolution
由扫描决定的数字图像的像素几何尺寸，它取决于激光扫描仪扫描IP的行间距，以及激光点扫描行走速度与模数转换器工作频率之比。
3.18
数字图像处理digital image processing
通过计算机对数字图像进行处理的方法和技术。CR数字图像常用的处理方法包括放大、缩小、灰度变换、对比度变换等。
4一般要求
4.1 检测人员
4.1.1 从事CR检测的人员应满足NB/T 47013.1的有关规定。
4.1.2 CR检测人员应在上岗前接受辐射安全知识、专门的CR理论和实际操作培训，并取得相应的资格。
4.1.3 CR检测人员未经矫正或经矫正的近(距)视力和远(距)视力应不低于5.0(小数记录值为1.0)，测试方法应符合GB 11533的规定。从事数字图像评定的人员应每年接受一次视力检查。
4.2检测设备和器材
4.2.1 射线源
应选择焦点尺寸、管电压范围和额定功率等满足检测对象和技术要求的X射线机。
4.2.2 CR系统
应根据检测对象和技术要求选择适用的CR系统。系统性能测试条件及测试方法按GB/T 21356的规定执行。系统至少应满足以下性能指标：
a)图像几何畸变应小于±2％；
b)扫描仪和IP板之间不应存在抖动、滑动，或抖动低于系统噪声水平；
c)图像同一水平线上，中心区域与边缘背景灰度变化应不超过±10％；
d)其他性能指标包括：信噪比、激光束功能、阴影、影像擦除、伪影等。
4.2.2.1成像板(IP)
IP的质量合格证中至少应包括IP的类型和规格、动态范围、激发响应时间、化学成分等主要性能参数。用户应按制造商推荐的温度和湿度条件予以使用和保存，并避免不必要的照射。对厚度较小的被检工件应选择感光速度较慢的IP，对厚度较大的被检工件可选择感光速度较快的IP。
4.2.2.2扫描仪
激光扫描仪的质量合格证中至少应包括规格、扫描尺寸、输入电压、扫描分辨率、激光束焦点尺寸、扫描步进速度等主要性能参数，且其功能和性能至少满足以下要求：
a)扫描仪应具有扫描和擦除功能，擦除后残留潜影灰度值不得高于系统最大灰度的5％；
b)扫描激光功率应满足信号采集的要求；
c)扫描仪的光电倍增管电压或增益、扫描分辨率应可调；
d)激光束应无颤动，且不存在伪影和扫描线丢失现象。
4.2.2.3显示器
应满足以下最低要求：
a)最低亮度250cd/m2；
b)显示器至少256灰度级；
c)可显示的最低光强比1：250；
d)显示至少1M像素，像素尺寸小于0.3mm。
4.2.2.4系统专用软件
应至少包括如下功能：
a)测量功能：包括灰度测量、空间分辨率测量、信噪比测量、几何尺寸测量等；
b)调整功能：包括灰度变换、对比度调节、图像缩放等；
c)标记功能。
4.2.3像质计
4.2.3.1线型像质计
a)线型像质计用于测定数字图像的对比灵敏度，包括通用线型像质计和等径线型像质计两种，其型号和规格应符合JB/T 7902的规定；
b)线型像质计的材料代号、材料和不同材料的线型像质计适用的被检工件材料范围可按表1的规定执行，线型像质计材料的吸收系数应尽可能接近或等同于被检材料的吸收系数，任何情况下不能高于被检材料的吸收系数。
表1 不同材料的线型像质计适用的材料范围
线型像质计材料代号 Al Ti Fe Ni Cu
线型像质计材料 工业纯铝 工业纯钛 碳素钢 镍-铬合金 3#纯铜
适用材料范围 铝，铝合金 钛，钛合金 钢 镍、镍合金 铜，铜合金

4.2.3.2双线型像质计
a)双线型像质计用于测量CR系统分辨率和数字图像分辨率；
b)双线型像质计的型号和规格应符合GB/T 23901.5的要求。
4.2.4检测设备器材的功能及性能应符合上述要求，且应提供相应的证明文件。
4.2.5校准或运行核查
4.2.5.1 每年至少对CR系统性能中的几何畸变、抖动、均匀性、激光束功能、阴影、伪影等进行1次校准或核查，并记录。
4.2.5.2 每年至少应对使用中的曝光曲线进行l次核查。当射线机重要部件更换或经过修理后，应重新制作曝光曲线。
4.2.5.3运行核查
存在如下情况应进行CR系统核查并记录，核查方法可参照GB/T 21356：
a)系统改变时(包括各部件的维修、更换、软件升级等)；
b)在系统停止使用3个月以上，重新使用时；
c)正常使用条件下，用户可根据产品说明书和使用频率，在工艺文件中规定核查频次，并按规定实施核查。
4.3检测技术等级
4.3.1 CR检测技术分为三级：A级——低灵敏度技术；AB级——中灵敏度技术；B级——高灵敏度技术。
4.3.2 CR检测技术等级选择应符合相关法规、标准和设计技术文件的要求，同时还应满足合同双方商定的其他技术要求。对承压设备对接焊缝，一般推荐采用AB级检测技术进行检测。对重要设备和结构的，以及以特殊材料和特殊焊接工艺制作的对接焊缝，可采用B级检测技术进行检测。
4.3.3 当某些检测条件不能满足AB级(或B级)检测技术的要求时，经合同双方商定，在采取有效补偿措施(例如增加曝光量或选用信噪比更高的系统等)的前提下，若数字图像质量达到了AB级(或B级)检测技术的规定，则可认为按AB级(或B级)检测技术进行了检测。
4.3.4如果检测中射线源至被检工件表面的距离f不满足5.7的要求，则4.3.3规定不适用。
4.3.5在用承压设备CR检测中，检测的某些条件不能满足AB级检测技术的要求时，经合同双方商定，在采取有效补偿措施(例如增加曝光量或选用信噪比更高的系统等)前提下可采用A级检测技术进行检测，但应同时采用其他无损检测方法进行补充检测。
4.4检测工艺文件
4.4.1 检测工艺文件包括工艺规程和操作指导书。
4.4.2工艺规程除满足NB/T 47013.1的要求外，还应规定下列相关因素的具体范围或要求，如相关因素的变化超出规定时，应重新编制或修订工艺规程：
a)适用的结构、材料类别及厚度；
b)射线源能量范围及焦点尺寸；
c)检测技术等级；
d)透照方式；
e)IP种类及型号；
f)线型像质计和双线型像质计型号；
g)金属屏种类及厚度；
h)扫描仪型号及参数设置；
i)数字图像显示器。
4.4.3 应根据工艺规程的内容以及被检工件的检测要求编写操作指导书，其内容除满足NB/T 47013.1的要求外，至少还应包括：
a)检测设备器材：射线源(焦点尺寸)、IP、金属屏(种类和厚度)、像质计(种类和型号)、背散射屏蔽铅板、标记、扫描仪和观察设备等；
b)检测技术与工艺：采用的检测技术等级、透照方式(射线源与被检工件以及IP之间的相对位置)、参数选择(射线源、IP、曝光条件)、像质计与标记的类型和放置等；
c)扫描仪参数；
d)图像处理技术；
e)数字图像质量要求：分辨率、对比灵敏度、归一化信噪比、标记等；
f)验收标准；
g)操作指导书的验证要求。
4.4.4首次使用的操作指导书应进行工艺验证，以验证数字图像质量是否能达到标准规定的要求。验证可通过专门的透照试验进行或以产品的第一批数字图像作为验证依据，验证数字图像应做出标识。
4.5 安全要求
4.5.1 检测环境应满足系统运行对环境(温度、湿度、接地、电磁辐射、振动等)的要求。
4.5.2辐射防护应符合GB 18871和GBZ 117的有关规定。
4.5.3现场进行CR检测前，应按GBZ 117的规定为其划定辐射控制区和管理区、设置警告标志。检测工作人员应佩戴个人剂量计，并携带剂量报警仪。
5检测工艺及其选择
5.1 检测时机
5.1.1 检测时机应满足相关法规、标准和设计技术文件的要求，同时还应满足合同双方商定的其他技术要求。
5.1.2 除非另有规定，CR检测应在焊接完成后进行，对有延迟裂纹倾向的材料，至少应在焊接完成24h后进行CR检测。
5.2检测区
5.2.1 检测区宽度应满足相关法规、标准和设计技术文件的要求，同时还应满足合同双方商定的其他技术要求，检测区包括焊缝金属及相对于焊缝边缘至少为5mm的相邻母材区域。
5.2.2对于电渣焊对接焊缝，其检测区宽度应由合同双方商定或通过实际测量热影响区确定。
5.3表面要求
在CR检测之前，对接焊缝的表面应经目视检测合格。表面的不规则状态在数字图像上的影像不得掩盖或干扰缺陷影像，否则应对表面作适当修整。
5.4射线能量
5.4.1 在保证穿透力的前提下，CR检测宜选用较低的管电压。在采用较高管电压时，应保证适当的曝光量。图1规定了不同材料、不同透照厚度允许采用的最高X射线管电压。
5.4.2对截面厚度变化大的承压设备，在保证数字图像质量满足5.16要求的前提下，允许采用超过图1规定的X射线管电压。但对钢、铜及铜合金、镍及镍合金材料，管电压增量应不超过50kV；对钛及钛合金材料，管电压增量应不超过40kV；对铝及铝合金材料，管电压增量应不超过30kV。
5.4.3按照B级检测技术检测时，宜选用结构噪声较低的IP。如选用结构噪声较高的IP，采用的最高X射线管电压宜比图1所示值低20％。
5.5 IP和金属屏
5.5.1 应根据被检工件材质、透照厚度和管电压选择合适的IP和金属屏。表2和表3分别给出了常用金属材料CR检测时前金属屏的材料和厚度选择要求，金属屏应符合JB/T 5075的要求。
5.5.2 当使用金属屏时，IP涂层面和前屏之间应当良好接触；IP背面可使用铅屏，当被检工件较薄时，使用钢或铜屏能取得更好的效果。

允许的最高管电压，kV
透明厚度W/mm
说明：
1——铜及铜合金、镍及镍合金；
2——钢；
3——钛及钛合金；
4——铝及铝合金。
图1 不同透照厚度允许的最高X射线管电压
表2前金属屏的材料和厚度——钢、铜及铜合金、镍及镍合金
射线能量 前金属屏的类型和厚度/mm
管电压≤50kV 无
50kV<管电压≤250kV ≤0.1(Pb)
250kV<管电压≤450kV ≤0.3(Pb)
注：铅屏可完全或部分由Fe或Cu屏代替，厚度为铅屏的3倍。

表3前金属屏的材料和厚度——铝及铝合金、钛及钛合金
射线能量 前金属屏的类型和厚度/mm
管电压≤150kV ≤0.03(Pb)
150kV<管电压≤450kV ≤0.2(Pb)
注：可在被检工件与IP暗盒之间使用0.1mm铅质滤光板，暗盒内使用0.1mm铅金属屏，替代0.2mm铅金属屏。

5.6透照布置
5.6.1 透照方式
应根据被检工件特点和技术条件的要求选择适宜的透照方式。在可实施的情况下，应优先选用单壁透照方式。只当单壁透照不能实施时，才允许采用双壁透照方式。典型的透照方式参见NB/T 47013.2—2015附录E。
5.6.2透照方向
透照时射线束中心一般应垂直指向透照区中心，并与工件表面法线重合，需要时也可选用有利于发现缺陷的方向透照。
5.6.3一次透照长度
5.6.3.1 一次透照长度通过透照厚度比K进行控制。不同检测技术等级和不同类型对接焊缝的K值应符合表4的规定。通过K值确定的整条环向对接焊缝所需的透照次数可参照NB/T 47013.2—2015附录F的曲线图确定。
5.6.3.2采用射线源在内偏心透照(F0.12时，相隔120°或60°透照3次。垂直透照重叠成像时，一般应相隔120°或60°透照3次。
按照上述规定进行多次透照时，相邻数字图像有效评定区的重叠应保证覆盖被检测区的整个体积范围，如最少曝光次数不能满足100％覆盖要求，则应增加曝光次数。
5.6.5.3特殊情况
由于结构原因不能按5.6.5.2规定的间隔角度进行多次透照，经合同双方商定，可不再强制执行5.6.5.2规定的透照间隔角度，但应采取措施尽量扩大缺陷可检出范围，同时应保证在评定范围内图像质量满足本部分要求，并在检测报告中对有关情况进行说明。
5.6.5.4局部检测
不要求100％检测的小径管环向焊接接头的透照次数由合同双方商定。