GB/T 17925-2024 PDF English
US$560.00 · In stock · Download in 9 secondsGB/T 17925-2024: Practice for X-ray digital radioscopic examination of cylinder weld Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedureStatus: Valid GB/T 17925: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB/T 17925-2024 | English | 560 |
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Practice for X-ray digital radioscopic examination of cylinder weld
| Valid |
| GB/T 17925-2011 | English | 689 |
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Standard practice for X-ray digital radioscopic examination of cylinder weld
| Valid |
| GB 17925-1999 | English | 559 |
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4 days
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Standard practice for X-ray real-time examination of cylinders weld
| Obsolete |
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GB/T 17925-2024: Practice for X-ray digital radioscopic examination of cylinder weld---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT17925-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.020.30
CCS J 74
Replacing GB/T 17925-2011
Practice for X-ray digital radioscopic examination of
cylinder weld
Issued on: DECEMBER 31, 2024
Implemented on: JULY 01, 2025
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword... 3
1 Scope... 6
2 Normative references... 6
3 Terms and definitions... 7
4 Symbols... 8
5 General requirements... 9
6 Testing environment and working conditions... 12
7 Testing timing and workpiece surface preparation... 13
8 Testing technology and process... 13
9 Image information marking... 18
10 Image quality index measurement and requirements... 18
11 Image observation, processing and dimensional measurement... 22
12 Quality classification of radiographic testing of gas cylinder butt joints... 23
13 Image storage... 23
14 Test record and report... 23
Appendix A (Normative) Determination of exposure-grayscale response curve of flat
panel detector... 24
Appendix B (Normative) Minimum number of penetrations for the entire
circumferential weld... 27
Appendix C (Normative) Determination of basic spatial resolution... 31
Appendix D (Informative) Test report and record form... 34
Practice for X-ray digital radioscopic examination of
cylinder weld
1 Scope
This document specifies the flat panel detector X-ray digital radioscopic (DR)
examination technology, equipment, process and image quality requirements for fusion
welded butt joints of gas cylinders during manufacturing.
This document is applicable to DR examination of cylinder weld made of steel and
nonferrous metal materials with a nominal thickness of 1.5 mm ~ 16.0 mm and a
nominal diameter of 100 mm ~ 1 200 mm.
This document can be used as a reference for DR examination of other gas cylinders of
similar specifications, sizes, and materials, as well as fusion-welded butt joints of in-
use gas cylinders.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this
document and are indispensable for its application. For dated references, only the
edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
GB/T 12604.11, Non-destructive testing - Terminology - Terms used in X-ray
digital radioscopic testing
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 unsharpness and basic spatial resolution value using
duplex wire-type image quality indicators
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
JB/T 7902, Non-destructive testing - Specification for wire-type image quality
indicators
3 Terms and definitions
For the purpose of this document, terms and definitions given in GB/T 12604.11, NB/T
47013.1 and NB/T 47013.2, as well as the following apply.
3.1
system resolution ratio
The measured value of a duplex wire image quality indicator placed directly on the
detector surface.
3.2
image resolution ratio
The measured value of a duplex wire image quality indicator placed on the base material
on the source side of the weld being inspected.
3.3
total unsharpness
The image unsharpness composed of the inherent unsharpness of the detector and the
geometric unsharpness.
3.4
normalized signal-to-noise ratio
Normalized signal-to-noise ratio based on resolution ratio.
3.5
amount of exposure during single frame
The product of tube current and the time of exposure during single frame.
3.6
multiframe superposition
The signal processing process of superimposing and averaging the gray-scale values of
multiple images collected while keeping the relative positions of the radiation source,
workpiece and imaging plate unchanged.
3.7
accumulated exposure
5 General requirements
5.1 Detection system
5.1.1 X-ray machine
5.1.1.1 High-frequency constant-voltage small-focus X-ray machine should be selected.
The operating frequency of its high-voltage generator shall not be less than 20 kHz; the
ripple factor (the peak-to-peak value of the AC component in the DC voltage output by
the high-voltage generator of the X-ray machine) shall be less than 1%; the effective
focal spot size shall not be greater than 1.5 mm.
5.1.1.2 The energy range of the X-ray machine shall be selected based on the material,
penetrated thickness and arrangement of the gas cylinder being inspected, combined
with the process requirements of high-voltage transillumination.
5.1.2 Flat panel detector
5.1.2.1 A flat panel detector shall be used.
5.1.2.2 The array element size of the detector should not be larger than 160 μm.
5.1.2.3 The analog-to-digital conversion bit number of the detector shall be no less than
12 bits, and the exposure-grayscale linear range should be no less than 75% of the full
grayscale.
5.1.3 Computer system
5.1.3.1 The configuration of the computer host shall be compatible with the flat panel
detector, X-ray machine control system and control system of the inspection tooling
used.
5.1.3.2 The computer system shall be equipped with a large memory and hard disk, and
shall have a data backup system.
5.1.3.3 The computer system shall be equipped with a high-brightness and high-
resolution display and shall meet the following requirements.
a) Brightness not less than 250 cd/m2;
b) Capable of displaying at least 256 gray levels;
c) Capable of displaying at least 2 million pixels, with a pixel size of less than
0.3 mm;
d) The minimum displayable light intensity ratio is 1.250.
5.1.4 System software
5.1.4.1 The system software shall have the functions of image acquisition, image
processing, image measurement and annotation, and image storage.
5.1.4.2 The image acquisition function shall include the adjustment and control of the
X-ray machine, detector, and inspection tooling.
5.1.4.3 The image processing function shall include various noise reduction functions
as well as image scaling, rotation, mirroring, contrast and brightness adjustment
functions.
5.1.4.4 The image measurement and annotation function shall include grayscale
measurement, resolution measurement, signal-to-noise ratio and normalized signal-to-
noise ratio measurement, geometric dimension measurement and defect marking, and
position annotation functions.
5.1.4.5 The image storage function shall include the establishment and classification
management of image libraries, as well as browsing, retrieval and search functions.
5.1.5 Inspection tooling
5.1.5.1 The inspection tooling shall include an X-ray machine-detector tooling, a gas
cylinder conveyor and a gas cylinder inspection platform.
5.1.5.2 The X-ray machine-detector tooling and the gas cylinder inspection platform
shall be able to achieve relative movement in multiple dimensions, such as front and
back, up and down, left and right rotation, and deflection, to achieve the following
functions.
a) Carry out testing on any designated part or range;
b) Adjust the transillumination arrangement according to the needs, such as
selecting appropriate F and b;
c) Adjust the illumination angle for detection.
5.1.5.3 Inspection tooling with automatic position tracking function and positioning
marking function shall meet the following requirements.
b) Testing equipment (X-ray machine, detector, inspection tooling, image quality
indicator, scattered radiation protection equipment, marking, system software,
display, etc.);
c) Testing process (illumination parameters, geometric parameters, acquisition
parameters, etc.);
d) Image quality assessment.
5.3.3 In addition to meeting the requirements of NB/T 47013.1, the operating
instructions shall at least include.
a) Basis for preparation;
b) Type and specification of applicable gas cylinders;
c) Testing equipment (X-ray machine, detector, inspection tooling, image quality
indicator, scattered radiation protection equipment, marking, system software,
display, etc.);
d) Testing process (illumination parameters, geometric parameters, acquisition
parameters, etc.);
e) Testing mark;
f) Image evaluation (gray value, normalized signal-to-noise ratio, image
resolution, image sensitivity, etc.);
g) Process verification image number.
5.3.4 The operating instructions shall be subject to process verification when first used.
The verification is generally carried out on the gas cylinder being tested, and may also
be carried out using a comparison test block or a simulated test block.
6 Testing environment and working conditions
6.1 The indoor temperature of the operating room and the assessment room shall be 15 ℃
~ 25 ℃; the relative humidity shall be less than or equal to 80%.
6.2 The temperature of the X-ray exposure room shall be 5 ℃ ~ 30 ℃; the relative
humidity shall be less than or equal to 80%; there shall be an exhaust device in the room.
6.3 The power supply voltage fluctuation range shall not exceed ±5%.
6.4 The detection equipment housing and the high-voltage generator of the radiation
source shall be effectively grounded, and the grounding resistance shall be less than or
equal to 4 Ω; the high-voltage generator of the radiation source shall have an
independent grounding wire.
7 Testing timing and workpiece surface preparation
7.1 Testing timing
Cylinder weld DR testing shall generally be carried out after welding and before heat
treatment. For products made of materials that are prone to delayed cracking after
welding, testing shall be carried out 24 hours after welding is completed. For products
made of materials prone to reheat cracking, another test shall be carried out after heat
treatment.
7.2 Surface preparation
The weld surface of the gas cylinder under inspection shall not have grease, rust, oxide
scale or other factors that affect the inspection (such as rough welding waves, surface
grooves between multi-layer welding beads, and surface pits, gouges, spatter, weld
scars, welding slag, etc. of the weld). The irregular state of the surface shall not affect
the correctness and completeness of the inspection results. The weld bead height shall
not be greater than 2 mm, otherwise it shall be ground.
8 Testing technology and process
8.1 Testing technology level
The X-ray testing technology level specified in this document shall meet the AB level
specified in NB/T 47013.2 - medium sensitivity technology.
8.2 Imaging method
Imaging shall be performed using a motionless detection method.
8.3 X-ray energy selection
The tube voltage selected for cylinder weld DR examination should be higher than that
selected for film photography.
Note. Using a calibrated X-ray DR system and a higher tube voltage can achieve a
higher signal-to-noise ratio and sensitivity; alternatively, the exposure time can
be significantly reduced without reducing the sensitivity, thus improving the
efficiency.
The curve in Figure 1 can be used as the recommended value of X-ray tube voltage for
different materials and different penetration thicknesses. During testing, the tube
voltage can be selected within the range of ±20% of the recommended value according
to the workpiece and equipment conditions.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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