This standard is applicable to ultrasonic flaw detection of large-area corrosion-resistant cladding layers on the surface of parent materials, including inspection of cladding defects in the weld cladding layer and the fusion condition of the weld cladding layer and the parent material. Ultrasonic flaw detection of other weld cladding layers can also be implemented as a reference. JB/T 8931-1999 Ultrasonic flaw detection method for weld cladding layers JB/T8931-1999 Standard download decompression password: www.bzxz.net

JB/T8931-—1999www.bzxz.net
This standard is equivalent to the content of ultrasonic flaw detection of weld overlay in Chapter T-543 of Volume V of ASME "Boiler and Pressure Vessel Code" in the United States, and has made necessary supplements and improvements based on my country's practical experience in flaw detection in this field. Compared with Volume V T-543 of ASME "Boiler and Pressure Vessel Code", this standard adds the use regulations of dual crystal straight probe and longitudinal wave oblique probe. This standard is formulated for the first time.
This standard is proposed and managed by the National Welding Standardization Technical Committee. The drafting units of this standard are Harbin Welding Research Institute and Boiler and Pressure Vessel Inspection Institute of Daqing Petroleum Administration Bureau. The main drafters of this standard are Pang Fengxiang, Zheng Qingming, Jin Chuanqi, Wei Jingyi, and Wan Jianqing. 405
1 Scope
Standard of the Machinery Industry of the People's Republic of China
Ultrasonic examination for cladding
Ultrasonic examination for claddingJB/T 8931—1999
This standard is applicable to ultrasonic testing of large-area corrosion-resistant cladding on the surface of the parent material, including the inspection of cladding defects in the cladding layer and the fusion condition of the cladding layer and the parent material. Ultrasonic testing of other cladding layers can also be implemented by reference. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. JB/T9404—1999 Probe model naming method for ultrasonic flaw detection JB/T10061—1999 General technical conditions for type A pulse reflection ultrasonic flaw detector JB/T10062—1999 Performance test method for ultrasonic flaw detection probe 3 Flaw detection instrument and probe
3.1 Type A pulse reflection ultrasonic flaw detector should be used, and all technical indicators should comply with JB/T10061. 3.2 The probe should comply with the requirements of JB/T9404 and JB/T10062. The following three types of probes are recommended. 3.2.1 Straight probe
The probe area should generally not exceed 625mm, and the frequency range is 2~5MHz. A 2.25MHz probe is recommended. 3.2.2 Dual crystal oblique probe and dual crystal straight probe
The angle between the two sound beams should be able to meet the effective sound field covering the entire detection area, so that the probe has the maximum sensitivity to the area. The total area of ​​the probe shall not exceed 325mm2, and the frequency is 2.25MHz. In order to achieve the required resolution, other frequencies may also be used, and the insulation between the two crystals shall be ensured to be good.
3.2.3 Longitudinal wave oblique probe
The probe frequency range is 2~5MHz.
4 Test block
The test block shall be made of the same material as the workpiece to be inspected or with similar acoustic properties. The thickness of the parent material shall be at least twice the thickness of the cladding layer, and it shall be made according to the same welding process as the workpiece. The parent material, cladding layer, and fusion surface shall not have defects greater than or equal to 2mm flat bottom hole equivalent. The surface condition of the test block shall be representative of the surface condition of the workpiece to be inspected. When inspecting from the parent material side, the difference between the parent material thickness of the workpiece to be inspected and the parent material thickness of the test block shall not exceed 25mm. Test block A is used to inspect the defects of the cladding layer, and test blocks B and Bz are used to inspect the fusion condition between the parent material and the cladding layer. The two types of test blocks are shown in Figures 1, 2, and 3. Approved by the State Bureau of Machinery Industry on June 24, 1999 406
Implementation on January 1, 2000
Weld overlay
Figure 2 Test block B
5 Calibration of flaw detection system
5.1 Calibration of sensitivity of dual-crystal oblique probe
Weld overlay
JB/T8931—1999
Figure 1 Test block A
Figure 3 Test block B2
Place the probe on the surface of the weld overlay of test block A, move the probe to obtain the maximum reflected wave from the 1.5mm long horizontal hole, adjust the attenuator and gain to make the echo amplitude 80%±5% of the full amplitude of the fluorescent screen, and use this as the benchmark sensitivity. 5.2 Calibration of the sensitivity of the dual crystal straight probe
5.2.1 Place the probe on the surface of the weld layer of test block A, move the probe to obtain the maximum reflected wave from the $3mm flat bottom hole, adjust the attenuator and gain, make the echo amplitude 80%±5% of the full scale of the fluorescent screen, and use this as the reference sensitivity. 5.2.2 Place the probe on the weld layer side of test block B, make the echo amplitude of the 10mm flat bottom hole 80%±5% of the full scale of the fluorescent screen, and use this as the reference sensitivity.
5.3 Calibration of the sensitivity of the longitudinal wave oblique probe
Place the probe on the parent material side of test block A, move the probe to obtain the maximum reflected wave from the g1.5mm long horizontal hole, adjust the attenuator and gain, make the echo amplitude 80%±5% of the full scale of the fluorescent screen, and use this as the reference sensitivity. 5.4 Single straight probe sensitivity calibration
Place the probe on the side of the weld overlay of test block B or the side of the parent material of test block Bz, so that the echo amplitude of the 10mm flat bottom hole is 407
80%±5% of the full width of the fluorescent screen, and use this as the reference sensitivity. 6 Attenuation surface state of weld overlay
JB/T8931—1999
When conducting ultrasonic flaw detection, the surface of the weld overlay should meet the requirements of the inspection process regulations to ensure that the probe can perform normal scanning. 7 Inspection process regulations
7.1 The inspection can be carried out from one side of the weld overlay or one side of the parent material. Good acoustic coupling between the probe and the contact surface should be ensured from either side. Industrial paste or glycerin is recommended as the bonding agent.
7.2 The weld overlay should be inspected using two reference sensitivities calibrated by test block A and test block B, or B. If there is any doubt about the inspection result, additional inspection can be carried out from the other side.
7.3 The scanning sensitivity should be increased by 6dB on the basis of the reference sensitivity. The scanning speed shall not exceed 150mm/s. The coverage rate of each scan shall be greater than 15% of the probe diameter.
7.4 When scanning with a dual crystal probe, the plane separating the piezoelectric crystals shall be parallel to the cladding direction. 7.5 After the instrument has worked continuously for 2 to 4 hours and the flaw detection is completed, the system sensitivity shall be calibrated. If the difference is less than 2dB, the sensitivity shall be recalibrated and the inspected parts shall be re-inspected.
7.6 All reflected signals shall be evaluated according to the reference sensitivity. 8 Inspection report
The inspection report shall at least include the following contents: a) workpiece name, material, cladding material, number and entrusting unit; b) instrument model, probe specifications, test block, sensitivity calibration, coupling agent and coupling compensation; c) inspection part and data, inspection part sketch, inspection standard and inspection results; d) operator and his qualifications, auditor and his qualifications; e) flaw detection date.
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