NB/T 20003.7-2021 Non-destructive testing for mechanical components in nuclear island of nuclear power plants - Part 7: Visual testing
1 Scope
This document specifies the technical requirements for visual testing of mechanical components in nuclear island of nuclear power plants during the manufacturing and installation process.
This document is applicable to the visual testing of nuclear materials, parts, welded joints, and surfaces for mechanical components in the nuclear island, and is used to determine the surface state, alignment of mating surfaces, deformation or leakage, integrity, etc., of components under test.
This document does not involve visual observations for the recognition of other non-destructive testing results.
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 11533 Standard for logarithmic visual acuity charts
GB/T 20968 Non-destructive testing - Aids to visual inspection - Selection of low-power magnifiers
NB/T 20003.1-2021 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 NB/T 20003.1-2021 and the following apply.
3.1
direct visual testing
visual testing method where there is a continuous light path between the testing personnel's eyes and the testing area
Note: The testing can be conducted without the aid of any equipment, or with the assistance of mirrors, or lenses (but not including telescopes).
3.2
remote visual testing
visual testing method where there is a discontinuous and intermittent light path between the testing personnel's eyes and the testing area
Note: The testing can be conducted using photography, video systems, automated systems, and robots.
3.3
neutral gray card
cardboard providing 18% reflectance neutral gray
Note: The neutral gray card used for visual testing typically features black lines with a width of less than or equal to 0.8 mm, used for verifying resolution.
4 General requirements
4.1 Visual testing personnel
The requirements specified in 5.1 of NB/T 20003.1-2021 shall apply.
Testing personnel shall undergo an examination of visual acuity annually. Their uncorrected or corrected near and far visual acuity shall not be less than 4.8, and the test method shall meet the requirements of GB 11533.
The testing personnel shall undergo color vision examination annually, and such examination shall not reveal color blindness or color weakness.
4.2 Testing documents
4.2.1 The testing documents shall include testing procedures, process cards, testing checklists, and other detailed testing documents, which shall meet the requirements of 5.4 in NB/T 20003.1-2021. Visual testing shall be carried out according to the effective written testing procedures.
4.2.2 The testing procedures shall cover at least the following contents:
——scope of application: type, size, testing range, and material of the workpiece under test;
——quoted laws, regulations, standards, design documents, etc.;
——qualification of testing personnel;
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Equipment and apparatus for visual testing
6 Visual testing method
7 Testing process
8 Evaluation and record
9 Testing report
Annex A (Informative) Typical appearance defects of steel fusion welded joints
Bibliography
