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)
GB/T 19799.1-2005 Non-destructive testing - Ultrasonic testing - Calibration block No.1 (ISO 2400: 1972, IDT)
GB/T 19799.2-2005 Non-destructive testing - Ultrasonic testing - Calibration block No.2 (ISO 7963: 1985, 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.
NB/T 20003.2-2010 The following standards are cited：
