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GB/T 31925-2015 PDF in English


GB/T 31925-2015 (GB/T31925-2015, GBT 31925-2015, GBT31925-2015)
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GB/T 31925-2015: PDF in English (GBT 31925-2015)

GB/T 31925-2015
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.20
H 26
Ultrasonic Test Methods of Heavy Wall
Thickness Seamless Steel Pipes and Tubes
ISSUED ON. SEPTEMBER 11, 2015
IMPLEMENTED ON. JUNE 1, 2016
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative References ... 4 
3 Terms and Definitions ... 5 
4 Test Principles ... 5 
5 Test Methods ... 5 
6 Reference Pipes ... 7 
7 Flaw Detection Device ... 10 
8 Test Conditions ... 11 
9 Test Procedures ... 11 
10 Result Assessment ... 12 
11 Test Report ... 13 
Foreword
This Standard was drafted as per the rules specified in GB/T 1.1-2009.
This Standard was proposed by China Iron and Steel Association.
This Standard shall be under the jurisdiction of National Technical Committee for
Standardization of Steel (SAC/TC 183).
Drafting organizations of this Standard. Hengyang Valin Steel Tube Co., Ltd.,
Zhongxing Energy Equipment Co., Ltd., Jiangsu Wujin Stainless Steel Pipe Group Co.,
Ltd., and China Metallurgical Information and Standardization Institute.
Chief drafting staffs of this Standard. Peng Shanyong, Deng Shirong, Qiu Yunlong,
Song Jianxin, Zhao Bin, Dong Li, Lai Chuanli, Zhao Haiying, and Zhang Li.
. Ultrasonic Test Methods of Heavy Wall
Thickness Seamless Steel Pipes and Tubes
1 Scope
This Standard specifies the piezoelectric ultrasonic test principles, test methods,
comparison specimen, flaw-detection equipment, test procedure, result assessment,
test report of seamless stainless steel pipe with the ratio of wall-thickness to outside
diameter in the range of 0.2~0.3.
This Standard is applicable to ultrasonic test of longitudinal and horizontal defects on
heavy wall seamless steel pipe for all kinds of uses, with the outside diameter no less
than 6mm. This Standard’s flaw-detection method is mainly against the test of metallic
discontinuities defects within the steel pipe, which is not applicable to the test of
laminar defects.
For the test of pipe with ratio of wall-thickness to outside diameter equals and is
greater than 0.3, it shall be carried out through the coordination between the buyer
and the seller.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) are applicable to this Standard.
GB/T 5777-2008 Seamless Steel Pipe and Tubing Methods for Ultrasonic Testing
GB/T 9445 Non-Destructive Testing - Qualification and Certification of NDT
Personnel
YB/T 4082 Measurement Method of Comprehensive Properties for Automatic
Ultrasonic Flaw Detection System for Steel Tubes
JB/T 10061 Commonly Used Specification for A-Mode Ultrasonic Flaw Detector
Using Pulse Echo Technique
5.4 When taking the automatic or manual test, select the coupling medium that has
good coupling effect and doesn’t damage the steel pipe surface.
6 Reference Pipes
6.1 Use
Reference pipes are used for the commissioning of flaw-detection device,
comprehensive performance test, and fixed-time calibration. The artificial defects on
the reference pipes serve as the assessment basis for the natural defect equivalence,
however, which shall not be understood, when the signal amplitude of the tested
natural defects equals to that of the artificial defects, the size of the two kinds of
defects equals absolutely; neither can it be understood the minimum defect size that
can be detected by this device.
6.2 Materials
Reference pipes and the tested steel pipes shall have the same nominal size, and
have the same or similar surface state, delivery state and acoustic performance.
Reference pipes shall not have the natural defects that may influence the calibration f
the test equipment.
6.3 Length
The length of reference pipes shall meet the requirements of test methods and test
equipment.
6.4 Artificial defect
6.4.1 Shape
The artificial defect for testing the longitudinal and transverse defects shall be the
longitudinal notch paralleling to the pipe axis and the transverse notch perpendicular
to the pipe axis; while their shapes of the cross-section shall be rectangular or
V-shaped (see Figure 3, and 4). The two side surfaces of rectangular notch shall be
parallel to each other and perpendicular to the bottom surface of the notch. When
processing through the electric erosion method, the notch’s bottom surface and
corners on the bottom surface are allowed to be slightly rounded. The angle of
V-shaped notch shall be 60°.
Figure 1 Heavy Wall Steel Pipe
Longitudinal Internal Defects
Ultrasonic Testing Schematic Diagram
Figure 2 Heavy Wall Steel Pipe
Longitudinal External Defects
Ultrasonic Testing Schematic Diagram
Artificial defects can be processed through the electronic erosion, mechanical and
other methods.
Longitudinal artificial defect shall be parallel to the steel pipe axis, the notch shall be
perpendicular to the steel pipe surface; transverse artificial defect shall be
perpendicular to the steel pipe axis, the notch shall be perpendicular to the steel pipe
surface.
Geometric dimension and shape of artificial defects shall be verified as per the
national measurement regulation. The depth of artificial defect can be measured
through optical, overriding and other methods.
The reference pipes shall have obvious label or number.
7 Flaw Detection Device
7.1 Flaw detector
7.1.1 Flaw detector shall be pulse reflective multi- or single-channel ultrasonic flaw
detector; its performance shall conform to the provisions of JB/T 10061; its attenuator
(gain) accuracy, vertical linearity and dynamic rang shall be calibrated qualified.
7.1.2 Flaw detector repletion frequency’s adjustable range shall meet the
requirement of flaw detection.
7.1.3 Flaw detector has the automatic alarm or defect signal output functions.
7.2 Probe
7.2.1 Piezoelectric ultrasonic probe’s working frequency can be selected within
1MHz~15 MHz; single probe’s wafer length or diameter shall be no more than 25mm;
but when the artificial defect length is less than 20mm, it shall be no more than 12mm.
7.2.2 Piezoelectric ultrasonic flaw detection can use line-focus or point-focus probe.
7.3 Detection device
The detection device for automatic inspection shall be equipped with high precision
adjustable mechanism for probe against the steel pipe’s relative location; and can
reliably lock or achieve good mechanical tracking; so as to ensure, under the dynamic
state, unchanged incident condition for acoustic beam against the steel pipe.
7.4 Transmission device
Transmission device for automatic inspection shall make the steel pipe pass through
the detection device at a uniform speed; and ensure, in the test, the steel pipe has
detection device’s circumferential sensitivity difference, the test result shall conform to
the provision of this Standard. When the longitudinal internal and external defects are
tested for twice, the length of blind area shall only be determined by testing the
longitudinal external defect.
9.2.2 The operating speed of the device during the test period shall be the same as
that during the normal inspection period. For multi-channel flaw detection device, if
whose every channel is tested independently, then the test speed can equal to the
ratio of normal inspection speed to the number of channels of the device.
9.3 Flaw detection
9.3.1 After the test results conform to the requirement of 9.2.1, can the flaw
detection be carried out. Flaw detection shall be implemented batch by batch, and
piece by piece.
9.3.2 Flaw detecting staff shall, during the inspection period, take reliable monitoring
measures for the defect indication signals, so as to prevent the undetected defects.
9.4 Device calibration
9.4.1 For the same-specification steel pipe, during its continuous flaw detection
period, use the reference pipes to conduct fixed-time calibration against the flaw
detection device, and the calibration time interval shall not exceed 4h. For the
same-specification steel pipe, during the commencement, completion, and
intermediate of continuous flaw detection period, if the device operators are changed,
then the device needs calibration, too. The calibration content can refer to 9.1.4 and
9.2.
9.4.2 If calibration result doesn’t conform to the requirement, then conduct
re-commissioning and re-test against the device; after it meets the requirement, then
the tested steel pipe after the previous calibration need repeat the flaw-detec...
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.