GB/T 41856.1-2022 English PDF (GBT41856.1-2022)
GB/T 41856.1-2022 English PDF (GBT41856.1-2022)
GB/T 41856.1-2022: Non-destructive testing - Industrial endoscopy visual testing - Part 1: Method
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
CCS J 04
Non-destructive testing - Industrial endoscopy visual testing
- Part 1: Method
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: OCTOBER 12, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 6
4 Method principle ... 6
5 Environmental requirements ... 7
6 Personnel requirements ... 7
7 Testing system ... 7
8 Testing ... 10
9 Result evaluation ... 12
10 Testing report ... 13
Appendix A (Informative) Comparison of structure and performance of three types of endoscopy testing systems ... 14
Appendix B (Informative) Endoscopy measurement methods ... 16
Non-destructive testing - Industrial endoscopy visual testing
- Part 1: Method
This document specifies the method principle, environmental requirements, personnel requirements, testing system, testing, result evaluation, and testing report of industrial endoscopy (hereinafter referred to as endoscopy) visual testing.
This document is applicable to the testing and evaluation of the inner surface state and internal structure of metal or non-metal parts and assembly components of industrial products.
2 Normative references
The contents of the following documents, through normative references in this text, constitute indispensable provisions of this document. Among them, for dated references, only the edition corresponding to that date applies to this document. For undated references, the latest edition (including all amendments) applies to this document. GB/T 9445 Non-destructive testing - Qualification and certification of NDT personnel
GB/T 20737 Non-destructive testing - General terms and definitions
GB/T 41856.2 Non-destructive testing - Industrial endoscopy visual testing - Part 2: Atlas
3 Terms and definitions
The terms and definitions defined in GB/T 20737 apply to this document. 4 Method principle
Without damaging the tested part or the operation of in-service equipment, for the parts or inner surface conditions that are difficult to be observed by direct visual testing, endoscopy visual testing uses an endoscopy testing system to test and evaluate them by means of optical images or photoelectric conversion video images. By changing different endoscopy probes (also known as scope bodies); changing the viewing direction or improving the field of view; and applying optical or photoelectric principles, FIND defects clearly, intuitively and effectively. Compare the measured image with the typical atlas; analyze and evaluate the real situation of the tested area or structure. 5 Environmental requirements
5.1 The ambient temperature and humidity of the testing site shall meet the requirements of the testing system.
5.2 There shall be no electromagnetic interference affecting the testing around the testing site.
5.3 The endoscopy testing system should have its own grounding protection power supply or be grounded independently. It shall be equipped with a voltage stabilizing device, to ensure that there is no static electricity accumulation during the working process. The grounding resistance should not be greater than 4 Ω.
5.4 When testing, it is advisable to avoid strong light or direct sunlight; choose a soft and quiet environment.
6 Personnel requirements
The personnel, who carry out the testing, shall be subject to qualification and certification according to GB/T 9445 or the system recognized by the parties to the contract; it shall obtain relevant qualification certificates for visual testing. Or the employer shall provide job training and operation authorization for them. 7 Testing system
7.1.1 The basic configuration of the endoscopy testing system is mainly composed of endoscopy probe, lighting source, control system, and display system.
7.1.2 Auxiliary functions such as manipulator, image recording transmission system, and video converter can be configured.
Endoscopy testing systems are classified according to imaging principles and light guide materials as follows.
a) Optical straight-rod endoscopy (rigid scope or straight-rod scope). Use the principle of optical imaging. Use the objective lens to generate the image signal. Use a medium to transmit the image. Use the eyepiece to directly observe. It can 7.4 Lighting source
7.4.1 In order to ensure the testing resolution ability of the endoscopy AND truly reflect the state of the inner surface of the tested part, a white light illumination source should be used.
7.4.2 According to the material and inner surface state of the tested part, adjust the illumination and the depth of field and angle of the endoscopy probe, to avoid reflection and glare.
7.5 Control system
The endoscopy testing system should have the function of adjusting focus and illumination. There are automatic and manual adjustments.
7.6 Display system
7.6.1 The resolution of the display system should not be lower than that of the endoscopy testing system.
7.6.2 The imaging quality of the endoscopy testing system should be tested using a resolution test card, to judge the imaging clarity, resolution, barrel-shaped distortion, color distortion, etc.
7.7 Measurement mode
The measurement mode of the endoscopy testing system is divided into two types: comparative measurement and absolute measurement. According to the testing requirements of the tested part, select a measurement mode. See Appendix B. 7.8 Testing software
The testing software should have functions such as image freeze-frame photography, video recording, zoom-in, comparison, etc.; and can perform color setting, brightness adjustment, file naming, image storage and recall, video/video playback, deletion, formatting, lighting color white balance, etc.
7.9 Auxiliary functions
Fiber optic or electronic video endoscopy shall have the following auxiliary functions - such as tool auxiliary channels and externally attached auxiliary tools, etc. - for operations such as foreign objects grasping, deburring, chamfering, diversion, and cleaning.
When grasping foreign objects, according to the material and shape of the excess objects, auxiliary grasping tools can be selected. The length is generally longer than the length of the insertion tube of endoscopy probe. When grabbing excess objects, it is advisable to avoid the auxiliary tools from scratching the surface of the tested part. When the grasping tool enters the working channel of the endoscopy, it shall be in a straightened and tightened state to facilitate grasping.
If burrs are found in the inner hole and inner cavity OR chamfering is required, the endoscopic electric grinding device with built-in tool channel can be selected for visual operation.
8.1 Testing preparation
8.1.1 Before testing, it is advisable to remove impurities and corrosive objects on the surface of the tested part; remove redundant objects that affect the testing and evaluation; so as to ensure the true state of the surface of the tested part.
8.1.2 According to the internal structure characteristics of the inspected part and the testing requirements, select the model and specification of the endoscopy probe. According to the testing steps, unfold and connect the testing system. Check the reliable grounding of the power supply, the stable placement of the instrument, and the normal start-up function of the instrument.
8.1.3 Before testing, the following elements should be paid attention to: a) Avoid dropping, colliding and crushing the lens of the endoscopy probe; b) Avoid cable crushing or sharp object cuts of the endoscopy probe;
c) Before testing, check whether the connection of the endoscopy probe is firm AND whether the surface of the endoscopy probe is intact;
d) Avoid damage or jamming of the endoscopy probe caused by foreign objects, obstacles or edge burrs in the tested part.
8.2 Testing process specification
Before testing, it shall prepare the corresponding testing process specification or testing operation documents. The contents shall at least include:
a) Information of the tested part and the tested range (testing area, location and orientation);
b) Reference to this document and acceptance requirements;
c) Qualification of testing personnel;
b) When manipulating the endoscopy probe for inspection, the bending radius of the tested part shall not be less than the minimum allowable bending radius of the probe. When inspecting or passing through a curved channel, the direction of the probe shall be controlled to keep the correct direction. When necessary, use tooling with rigid conduits to control, to avoid excessive twisting of the direction control knob. When not in use, the probe direction control knob shall be in the release position;
c) Process and analyze the acquired images;
d) When shutting down, operate in the reverse order of step a);
e) Clean the endoscopy probe (scope body).
184.108.40.206 Visual testing by measurable electronic video endoscopy
In addition to meeting the requirements of 220.127.116.11, the testing steps of measurable electronic video endoscopy visual testing shall also include the following elements: a) Select the measurement mode;
b) Use reference geometric measurement datum;
c) When measuring, take a larger magnification for images;
d) It is advisable to repeat the measurement for the same measurement object; take the average value as the measurement value.
18.104.22.168 Visual testing by electronic video endoscopy with tools
In addition to meeting the requirements of 22.214.171.124, the testing steps of the visual testing by electronic video endoscopy with tooling holes shall also include the following elements:
a) When the manipulator (fixture) enters the working channel of the endoscopy, it shall be in a tightened state; and the endoscopy probe shall be straightened; b) According to the material and shape of the excess, correctly select the manipulator to take out the excess. When grasping, the manipulator shall not damage the tested product; and shall not push the excess into a position where it cannot be grasped. 9 Result evaluation
9.1 Identification of defect type
Compare the image determined according to GB/T 41856.2 with the testing image, to identify the type of defect.
9.2 Defect measurement
According to the testing requirements, select the measurement mode and reference geometric measurement datum. When measuring, the image should use a larger magnification. Repeat the measurement on the same measurement object; take the average value as the measured value. See Appendix B for endoscopy measurement methods.
9.3 Result evaluation
According to the acceptance requirements, evaluate the type of defect and measurement data; give the conclusion of acceptance, repair or rejection.
10 Testing report
After endoscopy visual testing, the testing results and related testing parameters shall be recorded in detail. The testing report shall be filled out.
Details regarding format and content should be specified in the application-specific documentation OR agreed between the contracting parties. The testing report shall at least include the following:
a) Entrusting organization and delivery-for-testing date;
b) Information of the tested part, such as name, material designation, and quantity; c) Reference to this document or acceptance requirements;
d) Specification/model, measurement mode, and relevant basis of the testing instrument;
e) Testing area;
f) Testing conclusions (records are given in words or schematic diagrams; photos are provided if necessary);
g) Signatures of testers, report writers and reviewers AND their dates; h) Testing report number and date.
Endoscopy measurement methods
When performing quantitative assessments of regions of interest on images, use endoscopy with measurement capabilities. Measurement dimensions include point-to- point, point-to-line, point-to-surface, surface-to-surface, perimeter, area, etc. Endoscopy measurement methods are divided into two modes: comparative
measurement and absolute measurement.
B.2 Comparative measurement mode
The comparative measurement mode needs to input the known size of the reference object. Through the comparison of relative quantities, after determining the pixel division from the software, it measures the defect size or the region of interest. Some use the notch on the lens or project two laser points to realize it. The size of the notch and the distance between the two laser points are known. When measuring, the lens is relatively perpendicular to the tested part; otherwise it is impossible to judge its relative proportional relationship. The comparative measurement mode has high requirements for device orientation. The measurement accuracy is affected by the pixel resolution. B.3 Absolute measurement mode
The absolute measurement mode is based on the optical field geometry algorithm with the lens as the coordinate system. When measuring, there is no need to compare with the reference object. The mainstream technologies of absolute measurement mode are listed below:
- Single-objective lens laser measurement: The lens emits multiple laser points and projects them onto the surface of the object, to form a dot matrix on the measurement surface. Through the laser dislocation trigonometric function, calculate the three-dimensional coordinate value of each point on the surface of the object image; then realize the measurement;
- Single-objective lens grating measurement: The front of the lens has a grating fringe projection structure. Modulate the LED lights behind the grating for sequential lighting or brightness adjustment, to achieve different fringe scanning layout imaging. By solving the phase relationship of the fringes of each point on the object image, obtain the relative position between each point; then realize the