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GB/T 41856.1-2022 PDF in English

GB/T 41856.1-2022 (GB/T41856.1-2022, GBT 41856.1-2022, GBT41856.1-2022)
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Standards related to: GB/T 41856.1-2022

GB/T 41856.1-2022: PDF in English (GBT 41856.1-2022)

GB/T 41856.1-2022
ICS 19.100
CCS J 04
Non-destructive testing - Industrial endoscopy visual testing
- Part 1: Method
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
1 Scope
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
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
GB/T 20737 Non-destructive testing - General terms and definitions
GB/T 41856.2 Non-destructive testing - Industrial endoscopy visual testing - Part 2:
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 Composition
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.
7.2 Classification
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
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
8 Testing
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
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). Visual testing by measurable electronic video endoscopy
In addition to meeting the requirements of, 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. Visual testing by electronic video endoscopy with tools
In addition to meeting the requirements of, the testing steps of the visual testing
by electronic video endoscopy with tooling holes shall also include the following
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
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
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.
Appendix B
Endoscopy measurement methods
B.1 Overview
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
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.