Non-destructive testing for mechanical components in nuclear island of nuclear power plants - Part 2: Ultrasonic testing
1 Scope
This part of NB/T 20003 specifies:
——general technical requirements for ultrasonic testing, and relevant supplementary requirements and acceptance criteria for specific types of workpieces;
——technical requirements for measuring workpiece thickness by ultrasonic pulse-echo contact method.
This part is applicable to ultrasonic testing of raw materials and parts such as castings, sheets, forgings, pipes and bars of mechanical components in nuclear island of nuclear power plants, as well as welded joints, isolation layers, surfacing layers, composite plates and other materials during the fabrication and installation process.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 12604.1 Non-destructive testing - Terminology - Terms used in ultrasonic testing (GB/T 12604.1-2005, ISO 5577: 2000, IDT)
JB/T 8428-2006 Non-destructive testing - Blocks for ultrasonic testing
JB/T 9214-1999 Practice for evaluating performance characteristics of A scope ultrasonic pulse-echo testing systems
JB/T 10061-1999 Commonly used specification A-mode ultrasonic flaw detector using pulse echo technique
JB/T 10062-1999 Testing methods for performance of probes used in ultrasonic flaw detection
NB/T 20003.1-2010 Non-destructive testing for mechanical components in nuclear island of nuclear power plants - Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions established in GB/T 12604.1 and NB/T 20003.1-2010 and the following apply.
3.1
probe shoe
certain shape of material block inserted between the probe and the test object to improve coupling or protect the probe
3.2
wedge
special wedge piece that is placed between the transducer and the test object and can refract the ultrasonic beam at a given angle into the test object in case of acoustic contact with the above two
Note: it is commonly made of engineering plastics.
3.3
transducer
active component of the probe that can convert electrical energy into ultrasonic energy or vice versa
Note: it is also called crystal.
3.4
nominal angle of probe
refraction angle of probe indicated by a given material and temperature
3.5
nominal frequency
frequency of the probe indicated by the manufacturer
3.6
centre frequency
arithmetic average value of the corresponding frequency when the amplitude is 6dB lower than that of the peak frequency during the testing by pulse echo method
3.7
squint angle
the squint angle of the normal probe is the angle between the geometric axis of the probe and the main beam axis
The squint angle of the angle probe is the angle between the geometric axis of the probe and the projection of the main beam axis on the test surface.
3.8
standard block
material block with specified chemical composition, surface roughness, heat treatment and geometric shape, which is used to evaluate and calibrate ultrasonic testing equipment
3.9
reference block
test block with the same or similar material or chemical composition and the same or similar acoustic characteristics as the test object, and a specific reflector, which is used to adjust the sensitivity or time base range of ultrasonic testing equipment and compare the detected discontinuous signals with signals generated by known reflectors
3.10
reflector
an interface at which an ultrasonic beam encounters a change in acoustic impedance
3.11
time base range
ultrasonic path length that is displayed on a particular time base
3.12
creeping wave
wave generated at the first critical angle of incidence and propagated along the surface of the medium as a longitudinal wave
Note: Its sound velocity is basically equivalent to that of longitudinal wave.
3.13
DGS diagram
a series of curves describing the relationship between distance, echo amplitude (gain) and equivalent size of regular reflectors
Note: The X-axis usually represents the distance, while Y-axis represents the echo amplitude or gain. It is also known as AVG diagram.
3.14
DGS method
method of characterizing the equivalent size of the to-be-evaluated reflector by the diameter of the disc-shaped reflector with the same echo height as the to-be-evaluated reflector, using DGS diagram
Note: it is also known as AVG method.
Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 General requirements 4.1 Testing personnel 4.2 Testing documents 4.3 Testing range 4.4 Verification of procedures 5 Apparatus 5.1 Ultrasonic flaw detector 5.2 Probe 5.3 Coupling medium 5.4 Test blocks 5.5 Performance test 6 Testing conditions 6.1 Testing time 6.2 Testing area 6.3 Test surface 6.4 Surface preparation 6.5 Accessibility 6.6 Requirements for environment conditions 6.7 Test object 7 System calibration and recalibration 7.1 General requirements 7.2 Recalibration during testing 7.3 Precautions 8 Testing techniques 8.1 Scope 8.2 Normal beam wave testing and angle beam wave testing 8.3 Contact method and immersion method 8.4 Special techniques or new techniques 9 Testing 9.1 Scanning 9.2 Adjustment of time base range 9.3 Adjustment of sensitivity 9.4 Sensitivity compensation 9.5 Determination of indication 10 Evaluation 11 Acceptance 12 Castings 12.1 Scope 12.2 General requirements 12.3 Testing time 12.4 Testing area 12.5 Scanning 12.6 Reference block 12.7 Detectability evaluation 12.8 DAC curve 12.9 Supplementary testing 12.10 Record 12.11 Evaluation and quality grade 12.12 Acceptance criteria 13 Sheets 13.1 Scope 13.2 General requirements 13.3 Testing technique 13.4 Probe 13.5 Reference block 13.6 Testing time 13.7 Scanning 13.8 Basic sensitivity 13.9 Measurement of loss of back echo 13.10 Measurement of record of indications 13.11 Evaluation 13.12 Quality grade 13.13 Acceptance criteria 14 Forgings 14.1 Scope 14.2 General requirements 14.3 Classification of forgings 14.4 Apparatus 14.5 Test conditions 14.6 Testing 14.7 Evaluation and quality grade 14.8 Acceptance criteria 15 Forged and rolled bars 15.1 Scope 15.2 General requirements 15.3 Testing time 15.4 Reference block 15.5 Probe 15.6 Testing 15.7 Sensitivity 15.8 Record 15.9 Quality grade and acceptance criteria 16 Bolt materials 16.1 Scope 16.2 General requirements 16.3 Reference block 16.4 Probe 16.5 Testing time 16.6 Scanning 16.7 Sensitivity 16.8 Record 16.9 Quality grade and acceptance criteria 17 Pipes 17.1 Scope 17.2 General requirements 17.3 Testing time 17.4 Testing area 17.5 Testing technique 17.6 Probe 17.7 Coupling medium 17.8 Scanning method 17.9 Reference block 17.10 Automatic testing equipment 17.11 Calibration and recalibration 17.12 Additional requirements for automatic testing 17.13 Determination of indication 17.14 Record and acceptance criteria 18 Full penetration welded joints 18.1 Scope 18.2 General requirements 18.3 Testing conditions 18.4 Testing 18.5 Record and acceptance criteria 18.6 Testing of repair welding zone 19 Isolation layers, surfacing layers and composite plates 19.1 Scope 19.2 General requirements 19.3 Testing conditions 19.4 Reference block 19.5 Testing 19.6 Record and acceptance criteria 19.7 Testing of repair welding zone 20 Thickness measurement by ultrasonic pulse-echo contact method 20.1 Scope 20.2 General requirements 20.3 Apparatus 20.4 Testing conditions 20.5 System calibration and recalibration 20.6 Measuring method 20.7 Measurement 20.8 Records and reports of thickness measurement 21 Testing report and record 21.1 Testing report 21.2 Testing records Annex A (Normative) Screen height linearity Annex B (Normative) Testing of horizontal linearity and vertical linearity Annex C (Informative) Method for ultrasonic shear wave testing of steel castings Annex D (Informative) Ultrasonic shear wave circumferential scanning for forgings Annex E (Informative) Scanning of key forgings Annex F (Informative) Determination and calculation of attenuation coefficient of workpiece material Annex G (Informative) Ultrasonic testing of the centrifugal casting austenite main piping Annex H (Informative) Ultrasonic testing of dissimilar metal welded joints Annex I (Informative) Plotting of outline drawing at welded joint Annex J (Informative) Judgment of flaw nature
