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GB/T 34370.3-2017 English PDF (GBT34370.3-2017)

GB/T 34370.3-2017 English PDF (GBT34370.3-2017)

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GB/T 34370.3-2017: Nondestructive testing of amusement equipment -- Part 3: Magnetic particle testing

This Part of GB/T 34370 specifies the yoke method, coil method and current flow method of the magnetic particle testing method and the requirements for quality grading of amusement equipment. This Part applies to the testing of defects on the surface and near surface of ferromagnetic raw materials, parts and welded joint of amusement equipment. This Part does not apply to the testing of austenitic stainless steel and other non-ferromagnetic materials.
GB/T 34370.3-2017
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 97.200.40
Y 57
Nondestructive testing of amusement equipment -
Part 3. Magnetic particle testing
ISSUED ON. SEPTEMBER 29, 2017
IMPLEMENTED ON. APRIL 01, 2018
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Method summary ... 6
5 Safety requirements ... 7
6 Personnel requirements ... 8
7 Testing equipment and apparatus ... 8
8 Testing process procedures ... 13
9 Testing ... 14
10 Retesting ... 22
11 Demagnetization ... 22
12 Magnetic particle testing quality grading ... 23
13 Magnetic particle testing report ... 24
Annex A (informative) Waveform of various magnetizing electric currents, ammeter indication and conversion relationship ... 26
Annex B (informative) Typical magnetization methods for welds ... 27
Nondestructive testing of amusement equipment -
Part 3. Magnetic particle testing
1 Scope
This Part of GB/T 34370 specifies the yoke method, coil method and current flow method of the magnetic particle testing method and the requirements for quality grading of amusement equipment.
This Part applies to the testing of defects on the surface and near surface of ferromagnetic raw materials, parts and welded joint of amusement equipment. This Part does not apply to the testing of austenitic stainless steel and other non-ferromagnetic materials.
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 of the referenced document (including any amendments) applies.
GB/T 5097 Non-destructive testing - Penetrant testing and magnetic particle testing - Viewing conditions
GB/T 11533 Standard for logarithmic visual acuity charts
GB/T 12604.5 Non-destructive testing - Terminology - Terms used in
magnetic particle testing
GB/T 20306 Amusement devices terminology
GB/T 20737 Non-destructive testing - General terms and definitions
GB/T 23907 Non-destructive testing - Shims for magnetic particle testing GB/T 34370.1 Nondestructive testing of amusement equipment - Part 1.
General requirement
JB/T 6063 Non-destructive testing - Materials for magnetic particle testing JB/T 8290 Non-destructive testing instruments - Magnetic particle flaw
6 Personnel requirements
For personnel engaged in the magnetic particle testing of amusement
equipment, in addition to complying with the relevant provisions of GB/T 34370.1, the magnetic particle testing personnel shall have an uncorrected or corrected visual acuity of not less than 5.0 (the decimal number is 1.0), and shall not have color blindness. The testing method shall comply with the provisions of GB/T 11533. The testing personnel shall be subjected to an eye exam every 12 months.
7 Testing equipment and apparatus
7.1 Magnetic particle testing equipment
7.1.1 Basic requirements
The magnetic particle testing equipment shall comply with the provisions of JB/T 8290.
When using the yoke maximum spacing, the AC yoke shall have a lifting power of at least 45 N; the DC (including rectified current) yoke or permanent yoke shall have a lifting power of at least 177 N.
7.1.2 Power-off phase controller
When using the residual magnetic field method for testing, the AC flaw detector shall be equipped with power-off phase controller.
7.1.3 Black light irradiance and wavelength
When using the fluorescent magnetic particle testing, the black light (UV-A) used shall comply with the provisions of GB/T 5097, and the irradiation intensity on the surface of the workpiece to be tested shall be greater than or equal to 1000 ??W/cm2. Its wavelength shall be 315 nm to 400 nm, and the peak
wavelength is approximately 365 nm.
7.1.4 Demagnetization device
The demagnetization device shall ensure that the surface residual magnetic field after the workpiece is demagnetized is less than or equal to 0.3 mT (240 A/m).
7.1.5 Auxiliary equipment
Generally include the following equipment.
meters, illuminometers, magnetic field strength meters, milli-Tesla meters, Gauss meters, etc., shall be calibrated at least once a year.
8 Testing process procedures
8.1 General testing process procedures
Organizations engaged in the magnetic particle testing of amusement
equipment shall formulate general testing process procedures in accordance with the requirements of GB/T 34370.1 and this Part, and the contents shall at least include the following elements.
a) document number;
b) scope of application;
c) implemented standards and regulations;
d) qualification of testing personnel;
e) name and model, etc. of test equipment and apparatus;
f) type and grade of magnetic particle;
g) surface state of the workpiece to be tested;
h) timing of testing;
i) magnetic ink concentration and method of applying magnetic particle; j) magnetization method and magnetization specification;
k) testing sensitivity calibration and standard shim;
l) analysis and interpretation of the testing process and magnetic particle indication;
m) assessment and grading of testing results;
n) test record and report format;
o) data archiving;
p) signature of preparing (level), reviewing (level) and approving personnel, date.
8.2 Testing process card
When the coil is larger than 2 times and less than 10 times the cross-sectional area of the workpiece to be tested, the magnetizing electric current of the coil is calculated according to formula (4).
where.
(NI)h - the NI value calculated by the high fill factor coil of formula (3); (NI)l - the NI value calculated by the low fill factor coil of formula (1) or formula (2);
Y - the ratio of the cross-sectional area of the coil to the cross-sectional area of the workpiece.
9.4.2.6 The above formula does not apply to workpieces with a length to diameter ratio (L/D) of less than 2. For workpieces with a length to diameter ratio (L/D) of less than 2, if the coil method is to be used, the magnetic pole lengthening block can be used to increase the effective value of the length to diameter ratio or the standard shim can be used to determine the current value. For workpieces with a length to diameter ratio (L/D) greater than or equal to 15, (L/D) in the formula is taken as 15.
9.4.2.7 When the workpiece to be tested is too long, segmental magnetization shall be performed; the effective magnetization range of each magnetization shall not exceed its effective magnetization area, and there shall be some overlap, and the length of the overlap area shall not be less than 10 % of the segmental testing length. During the testing, the magnetizing electric current shall be determined based on the indication result of the standard shim. 9.4.2.8 When the hollow workpiece is tested, the D of formulas (1) to (3) shall be replaced by the effective diameter Deff. The effective diameter Deff is. a) For cylindrical workpieces.
where.
Do - the outer diameter of the cylinder, in millimeters (mm);
Di - the inner diameter of the cylinder, in millimeters (mm).
b) For non-cylindrical workpieces.
9.8 Observation of defect magnetic particle indications
9.8.1 Observation of magnetic particle indications shall be carried out immediately after the formation of magnetic particle indications.
9.8.2 In non-fluorescent magnetic particle testing, the evaluation of magnetic particle indication shall be carried out under visible light. Generally, the visible light illumination on the surface of the workpiece to be tested shall be greater than or equal to 1000 lx. When tested by portable equipment on site, and when it is limited by conditions, the visible light illumination may be appropriately reduced, but shall be no less than 500 lx.
In fluorescent magnetic particle testing, the irradiance of the black light used on the surface of the workpiece shall be greater than or equal to 1000 ??W/cm2, and the wavelength of the black light shall be in the range of 315 nm ~ 400 nm. The evaluation of magnetic particle indication shall be carried out in the darkroom or dark area. The visible light illumination in the darkroom or dark area shall be no more than 20 lx.
When entering the dark area, the testing personnel shall start fluorescence magnetic particle testing after at least 3 minutes of dark adaptation. When observing the fluorescent magnetic particle testing, the testing personnel shall not wear glasses that have an effect on the testing.
9.8.3 Except that it can be confirmed that the magnetic particle indication is caused by local magnetic unevenness of the workpiece material or improper operation, other magnetic particle indications shall be treated as defects. When identifying small magnetic particle indications, use a 2x to 10x magnifying glass for observation.
9.9 Classification and processing of magnetic particle indication
9.9.1 The magnetic particle indication is divided into relevant indication, non- relevant indication and false indication.
9.9.2 Magnetic particle indications with a ratio of length to width greater than 3 are treated as linear magnetic particle indications; magnetic particle indications with a ratio of length to width of 3 or less are treated as circular magnetic particle indications. Magnetic particle indications less than 0.5 mm in length are not counted.
9.9.3 When two or more magnetic particle indications are on the same straight line and the spacing is not more than 2 mm, it is treated as a magnetic particle indication, and its length is the sum of the two magnetic particle indications plus the spacing.
9.10 Testing record
The magnetic particle testing record shall include at least the contents specified in 8.2 and Clause 13.
10 Retesting
A retesting is required when one of the following conditions occurs.
a) When it is verified, using the standard shim, that the testing sensitivity does not meet the requirements at the end of the testing;
b) When the operation method is incorrect or the technical conditions are changed during the testing process.
11 Demagnetization
11.1 General requirements for demagnetization
Workpieces that need to be heated to 700 ??C or higher for heat treatment after the testing may be exempted from demagnetization. Workpieces that have one of the following conditions shall be demagnetized.
a) When the testing requires multiple magnetizations, for example, if the last magnetization is determined to have an adverse effect on the next
magnetization;
b) The residual magnetic field of the workpiece will have an adverse effect on subsequent machining;
c) The residual magnetic field of the workpiece will have an adverse effect on the testing or metering device;
d) The residual magnetic field of the workpiece will have an adverse effect on the welding;
e) Other necessary occasions.
11.2 Demagnetization methods
11.2.1 AC demagnetization method
The workpiece to be demagnetized is slowly withdrawn from the energized magnetizing coil until the workpiece leaves the coil more than 1 m, and the current is cut off. Or place the workpiece into an energized magnetizing coil,

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