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GB/T 29712-2013 English PDF (GBT29712-2013)

GB/T 29712-2013 English PDF (GBT29712-2013)

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GB/T 29712-2013: Non-destructive testing of welds -- Ultrasonic testing -- Acceptance levels

This standard specifies the ultrasonic acceptance level 2 and 3 for full penetration welded joints in ferritic steels, which correspond to the quality levels B and C welds in GB/T 19418. Since the level D welds usually do not require ultrasonic testing in GB/T 19418, there is no ultrasonic testing acceptance level corresponding to the quality level D weld requirements in GB/T 19418. The acceptance levels of this standard apply to ultrasonic testing in accordance with GB/T 11345.
GB/T 29712-2013
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 25.160.40
J 33
Non-destructive testing of welds -
Ultrasonic testing - Acceptance levels
ISSUED ON. SEPTEMBER 18, 2013
IMPLEMENTED ON. JUNE 01, 2014
Issued by. General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Measurement of indication length ... 5
4 Sensitivity setting and levels ... 5
5 Acceptance levels ... 6
5.1 General ... 6
5.2 Longitudinal indications ... 6
5.3 Transverse indications... 7
5.4 Grouping of indications... 7
5.5 Cumulative length of acceptable indications ... 8
Appendix A (Normative) Level ... 10
Appendix B (Normative) Fixed amplitude level technique ... 22
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009. This standard, through the redrafting method, modifies and adopts the ISO 11666.2010 ?€?Non-destructive testing of welds - Ultrasonic testing - Acceptance levels?€? (English version).
As compared with ISO 11666.2010, the main technical differences of this standard and their causes are as follows.
- Regarding the normative reference documents, in order to adapt to the technical conditions of China, the following adjustments were made.
?€? USE GB/T 19418 which equivalently adopts international standard to
replace ISO 5817 (see 5.1);
?€? USE GB/T 11345 which equivalently adopts international standard to
replace ISO 17640 (see 1, 5.1, 5.2);
?€? USE GB/T 29711 which equivalently adopts international standard to
replace ISO 23279 (see 5.1);
?€? DELETE the ISO 17635 standard, INCLUDE its relevant content directly
to the text (see 5.1).
This standard was proposed and shall be under the jurisdiction of the National Welding Standardization Technical Committee (SAC/TC 55).
Drafting organizations of this standard. Shanghai Materials Research Institute, China Special Equipment Inspection and Research Institute, Jiangsu Fangtian Power Technology Co., Ltd., Jining Ruixiang Mould Co., Ltd. (Shandong Jining Mould Factory).
The main drafters of this standard. Ding Jie, Jin Yufei, Jiang Wei, Zhuang Zhiqiang, Zheng Hui, Ma Junpeng, Wei Zhongrui, Wang Sen, Zhang Wenjie,
Ma Jun, Xi Lifeng.
Non-destructive testing of welds -
Ultrasonic testing - Acceptance levels
1 Scope
This standard specifies the ultrasonic acceptance level 2 and 3 for full penetration welded joints in ferritic steels, which correspond to the quality levels B and C welds in GB/T 19418. Since the level D welds usually do not require ultrasonic testing in GB/T 19418, there is no ultrasonic testing acceptance level corresponding to the quality level D weld requirements in GB/T 19418.
The acceptance levels of this standard apply to ultrasonic testing in accordance with GB/T 11345.
This standard applies to the examination of full penetration ferritic steel welds, with thicknesses from 8 mm to 100 mm. It can also be used for other types of welds, materials and thicknesses above 100 mm, provided that the
examinations have been performed with necessary consideration of the
geometry and acoustic properties of the component, and an adequate
sensitivity can be employed to enable the acceptance levels of this standard to be applied. Unless attenuation or requirements for higher resolution call for other frequencies, the nominal frequency of probes used in this standard is between 2M Hz and 5 MHz. The use of these acceptance levels in conjunction with frequencies outside this range needs to be considered carefully.
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 11345 Non-destructive testing of welds - Ultrasonic testing -
Techniques, testing levels, and assessment (GB/T 11345-2013, ISO
17640.2010, MOD)
GB/T 19418 Arc-welded joints in steel - Guidance on quality levels for
imperfections (GB/T 19418-2003, ISO 5817.1992, IDT)
GB/T 29711 Non-destructive testing of welds - Ultrasonic testing -
Characterization of indications in welds (GB/T 29711-2013, ISO 23279.2010, IDT)
3 Measurement of indication length
The length of an indication shall be determined by measuring the distance along the length over which the echo amplitude is above the evaluation level, using the fixed amplitude level technique as specified in Appendix B.
Alternative techniques for measuring indication length may be used when specified.
4 Sensitivity setting and levels
The sensitivity setting and subsequent weld examination shall use the same techniques. The setting of sensitivity may select one of the following techniques. a) Side-drilled hole technology. based on a 3 mm diameter side-drilled hole; b) Flat-bottom hole technology. distance-gain-size (DGS) curve based on flat-bottom holes;
c) Rectangular notch technology. a distance-amplitude-corrected (DAC)
curve of a rectangular notch of 1 mm depth and 1 mm width;
d) Tandem technology. a tandem technique based on a 6 mm diameter flat- bottom hole.
This standard uses four levels as specified in GB/T 11345.
1) Reference level;
2) Evaluation level;
3) Recording level (corresponding to two acceptance levels, the values are all derived from the relevant acceptance level - 4 dB);
4) Acceptance level (corresponding to two quality levels).
The specifications for all levels corresponding to the reference reflector are given in Table A.1.
The provisions for the levels are given in Appendix A.
a) t, for the plate thickness range 8 mm ??? t ??? 15 mm;
b) t/2 or 15 mm, whichever is greater, for the plate thickness t > 15 mm. Further testing shall be preferred, which requires the use of probes from other angles, as well as tandem testing (if agreed).
The final assessment shall be based on the highest echo amplitude indicated and the measured length.
5.3 Transverse indications
When it is specified to detect the transverse indication, the acceptance level is applied as described in 5.2.
5.4 Grouping of indications
The grouping is based on the length and the separation of the two individually acceptable indications which have amplitudes above the recording level. The length of a group shall not be used for further grouping.
For evaluation, a group of indications shall be considered as a single one, if. a) The distance dx, is less than 2 times the length of the longer indication (see Figure 1);
b) The distance dy, is less than half of the thickness of the plate but not more than 10 mm;
c) The distance dz, is less than half of the thickness of the plate but not more than 10 mm.
The combined length (see Figure 2) is shown in formula (1).
l12 = l1 + l2 + dx ...(1)
The combined length l12, and the larger maximum amplitude of the two
indications shall then be assessed against the applicable acceptance levels as given in Table A.1.

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