NB/T 20003.2-2021 Non-destructive testing for mechanical components in nuclear island of nuclear power plants - Part 2: Ultrasonic testing
1 Scope
This document specifies the ultrasonic testing methods and quality grading for raw materials or parts of mechanical components in nuclear island of nuclear power plants.
This document is applicable to ultrasonic testing during the manufacturing and installation of raw materials or parts such as castings, plates/sheets, forgings, bars, bolt materials, and pipes, as well as welded joints, surfacing layers, and buttering in mechanical components in nuclear island of nuclear power plants.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 12604.1 Non-destructive testing - Terminology - Ultrasonic testing
JB/T 8428 Non-destructive testing - General specification for ultrasonic blocks
JB/T 9214 Non-destructive testing - Test methods for evaluating performance characteristics of A-scan pulse-echo ultrasonic testing systems
NB/T 20003.1 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 given in GB/T 12604.1 and NB/T 20003.1 and the following apply.
3.1
reduction of back wall echo caused by the presence of discontinuities
BG/BF
ratio of the amplitude of the first back wall echo, BG, in an intact area near the flaw to the amplitude of the first back wall echo, BF, in the flaw area during forgings testing, expressed in decibels (dB)
3.2
reference sensitivity
sensitivity for adjusting the echo height of the reference reflector on the reference block or the back wall echo height of the tested workpiece to a certain reference level
3.3
scanning sensitivity
sensitivity used in actual testing, which is appropriately increased in decibels (dB) (gain) based on the reference sensitivity (3.2), according to the requirements for flaw testing, the type of probe, etc.
3.4
echodynamic patterns
envelope line representing the variation in the amplitude of the echo from a corresponding flaw reflector as the probe moves over a distance
4 General requirements
4.1 Testing personnel
Unless otherwise specified, ultrasonic testing personnel shall comply with the relevant requirements of NB/T 20003.1.
4.2 Testing documents
4.2.1 Basic requirements
The testing procedures or other testing documents shall meet the requirements of NB/T 20003.1. The testing shall be conducted according to valid testing procedures.
4.2.2 Testing procedures
The testing procedures shall include at least the essential and non-essential variables listed in Table 1, as well as the following content:
——Scope of application: Type, size, testing range and material of the tested workpiece;
——Reference laws, codes, standards, design documents, etc.;
——Qualification of testing personnel;
——Testing equipment and apparatus: Ultrasonic instrument, probe, couplant, automatic testing instrument (if applicable), standard block and (or) reference block;
——Testing conditions: Testing time, testing area and surface conditions;
——Testing method: Testing technique and scanning (test surface, testing range, and scanning direction);
——Recalibration method and requirements;
——Recording and evaluation requirements;
——Acceptance criteria;
——Content and format of the testing report.
When the content of the procedures changes, the procedures shall be revised and updated accordingly.
Table 1 Essential and non-essential variables in the procedures
Item Essential variable Non-essential variable
Material type, geometric shape, thickness, product type, etc., of the tested workpiece × —
Test surface × —
Testing techniques (contact method, liquid immersion method, etc.) × —
Angle and mode of acoustic waves propagating in the material × —
Type, frequency, and size of probe × —
Special probe, wedge, and probe shoe (when in use) × —
Model of ultrasonic instrument × —
Standard block and reference block × —
Scanning direction and range × —
Scanning method (manual or automatic) × —
Scanning coverage (only when coverage decreases) × —
Data recording method × —
Indication signal discrimination method × —
Method for measuring indication amplitude and size × —
Recalibration method × —
Data acquisition software (for automatic testing) × —
Data acquisition parameters (for automatic testing) × —
Personnel operation requirements (when specified) × —
Surface conditions (test surface, and reference block surface) — ×
Couplant grade or type — ×
Automatic alarm and/or recording device (when in use) — ×
Data to be recorded, including verification data (e.g., instrument settings) — ×
4.3 Testing range
The testing range and proportion of the test object shall comply with the requirements of relevant technical specifications, product design documents, or procurement technical documents.
4.4 Procedure demonstration
4.4.1 Scope of application
Testing procedure demonstration shall be conducted when required by relevant product design documents or procurement technical documents.
In addition, testing procedure demonstration should be carried out in the following situations:
——This type of test object is subjected to ultrasonic testing for the first time;
——Changes in characteristics of test object, testing conditions, and testing parameters significantly affect the testing results.
4.4.2 General principle
The testing procedure demonstration shall follow the following principle:
a) The testing in the process of demonstration shall take the test piece with representative flaw as the test object. The representative flaw may be an artificial reference reflector or actual manufacturing defect, and it shall be representative in nature, location, distribution, size, orientation, etc., and be capable of meeting the purpose and requirements of the demonstration testing.
b) The non-destructive testing unit shall carry out testing in accordance with valid testing procedures to prove whether the methods, techniques, testing systems, etc. described in the procedures can meet the testing purposes and requirements in terms of flaw testing and evaluation.
c) The non-destructive testing unit shall record the testing requirements, testing procedures, test pieces under demonstration, and testing results during demonstration and document them in writing.
4.4.3 Re-demonstration
When the values or value ranges of the essential variables listed in Table 1 of the procedures are changed, the procedures shall be re-demonstrated; when the values or value ranges of the non-essential variables listed in Table 1 of the procedures are changed, the procedures may be exempt from re-demonstration.
4.5 Equipment and apparatus
Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Ultrasonic testing methods for materials
6 Ultrasonic testing methods for full penetration welded joints
7 Ultrasonic testing method for surfacing layers and buttering
8 Testing report and records
Annex A (Informative) Methods for measurement and calculation of attenuation coefficient of workpiece material
Annex B (Informative) Recommended determination method for curved surface compensation
Annex C (Informative) Ultrasonic angle-beam probe testing method for castings
Annex D (Informative) Ultrasonic angle-beam probe testing method for plates/sheets
Annex E (Informative) Ultrasonic testing method for composite steel plates
Annex F (Informative) Ultrasonic shear wave circumferential scanning for forgings
Annex G (Informative) Ultrasonic testing method for austenitic stainless steel butt joints
Annex H (Informative) Judgment of flaw nature
Annex I (Informative) Thickness measurement with ultrasonic pulse-echo contact method
Bibliography
