NB/T 47013.11-2023 Nondestructive testing of pressure equipments - Part 11: Digital radiographic testing
1 Scope
1.1 This document specifies the DR testing technology and quality classification requirements for fusion welded joints of pressure elements made of metallic materials in pressure equipment. The metallic materials used to produce welded 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 DR testing of butt welds of butt joints for plates and tubes (hereinafter referred to as "butt welds") in the manufacture, installation, and in-service testing of pressure elements of pressure equipment.
1.3 The imaging devices applicable to this document are digital detector arrays.
1.4 The ray sources applicable to this document are X-ray sources and Ir192 and Se75 γ ray sources, where the maximum tube voltage of the X-ray machine does not exceed 600 kV.
1.5 This document may also serve as a reference for DR testing of butt welds for welded joints of supporting members and structural members and those for fillet joints of plug-in nozzles and mounted nozzles of the pressure equipment (hereinafter referred to as "fillet weld of socket").
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 14058 Apparatus for gamma radiography
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
GB/T 23901.5 Non-destructive testing - Image quality of radiographs - Part 5: Determination of the image quality unsharpness and basic spatial resolution value using duplex wire-type image quality indicators
JB/T 7902 Non-destructive testing - Specification for wire-type image quality indicators
JB/T 11608 Non-destructive testing instruments - Industrial X-ray apparatus for radiographic testing
NB/T 47013.1 Nondestructive testing of pressure equipments - Part 1: General requirements
NB/T 47013.2 Nondestructive testing of pressure equipments - Part 2: Radiographic testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in NB/T 47013.1 and the following apply.
3.1
pixel
basic component units of digital radiographic image, i.e., the dots composing a digital radiographic image
3.2
digital detector array, DDA
electronic device converting ray photon to digital signal, hereinafter referred to as "DDA"
3.3
image sensitivity
capability of the testing system to detect the minimum details in the image of the object
3.4
digital radiographic system
system composed of DDA and its processing units, which can convert ray photons into digital images, hereinafter referred to as "DR system"
3.5
resolution ratio
capacity of distinguishing the minimum distance between two adjacent details in unit length, which is expressed in lp/mm
3.6
resolution
capacity of distinguishing the minimum distance between two adjacent details, which is expressed in mm, and which is mutually numerically reciprocal to resolution by two times
3.7
system resolution ratio
capacity of DR system to distinguish the minimum distance between two adjacent details in unit length, also known as the basic spatial resolution ratio of the system, which is expressed in lp/mm
3.8
image resolution ratio
capacity of the testing system to distinguish the minimum distance between two adjacent details in unit length in the image of the object, also known as image spacial resolution ratio, which is expressed in lp/mm
3.9
image resolution
capacity of testing system to distinguish the minimum distance between two adjacent details in object image, which is expressed in mm
3.10
grey level
quantitative description for the brightness degree of black and white images obtained by DR system, 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 16 bit, the collected grey level is 216＝ 65536.
3.11
dark image
image output without ray radiography, which is also known as dark current image
3.12
dynamic range
ratio of the maximum grey value of the output image of DR system to the standard deviation of dark image
3.13
non-uniform responsivity
non-uniformity of output image brightness due to the inconsistent response of DDA to ray in case of uniform radiographing of an object or empty screen
3.14
bad pixel
white point or black point with overhigh or overlow grey value compared with adjacent pixel in dark image, which also refers to the anomaly point of the corrected image whose output value is far away from the average value of the image Bad pixels exist in the form of: single point, two adjacent points and multiple adjacent points, rows or columns.
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Foreword iii
Introduction vi
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Testing methods
6 Image quality and evaluation
7 Flaw identification and measurement
8 Result evaluation and quality grading
9 Image preservation and storage
10 Testing records and report
Annex A (Normative) Verification method of system resolution ratio
Annex B (Informative) Typical radiography modes
Annex C (Normative) Calculation of value b
Annex D (Informative) Calculation of the minimum radiography times of circumferential weld
Annex E (Normative) Recognition of IQI (duplex wire type)
Annex F (Normative) Test method for normalized signal-to-noise ratio
Bibliography
