GOST 27333-87
GOST 27333−87 nondestructive testing. Measurement of the specific electrical conductivity of non-ferrous metals eddy-current method
GOST 27333−87
Group B59
INTERSTATE STANDARD
NONDESTRUCTIVE TESTING
Measurement of specific electric conductivity
non-ferrous metals eddy-current method
Nondestructive testing. Measurement of electrical conductivity
of non-ferrous metals by eddy current method
AXTU 1809
ISS 19.100
77.040.20
Date of introduction 1988−07−01
INFORMATION DATA
1. DEVELOPERS
N. F. Petrakov, V. F., Berenson, K. V. Yurenkov, V. I. Dobatkin, G. S. Makarov, N. M. Naumov, V. T., Knyazev, P. T. Dashinski
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Item number |
| GOST 18353−79 |
Chapeau |
| GOST 2789−73 |
2.2 |
5. REISSUE
This standard applies to semi-finished products and parts from non-ferrous non-ferrous metals and alloys and sets the eddy current method of measuring specific electrical conductivity (hereafter conductivity) in the range from 0.5 to 37 MS/m.
The standard does not apply to wire and foil.
The essence of the method — according to GOST 18353.
1. EQUIPMENT
1.1. When measuring the electrical conductivity using the eddy current measuring specific electrical conductivity (hereafter eddy current gauges) with patch Converter having as display devices:
the digital display;
a dial indicator widget in units of electrical conductivity;
a dial indicator with a uniform scale, not widget, in units of electrical conductivity.
Frequency excitation current eddy current transducer must be at least 40 kHz.
1.1.1. Eddy current meters used in conjunction with a set of state standard samples of specific electrical conductivity (GSO).
1.1.2. Eddy current gauges should be believed.
1.2. The main relative error of measurement of the specific electrical conductivity using the GSO in the range from 0.5 to 3 MS/m should not exceed 3%, in the range over 3 to 37 MS/m should not exceed 2%.
1.3. Preparation of eddy current gauges to work (grounding, warming, offset against changes in the gap) must be held in accordance with the operating instructions.
2. THE REQUIREMENTS OF THE BUILDING CONTROL
2.1. The test object should have a flat pad whose dimensions and thickness at the place of measurement shall be as specified in the operational documentation of eddy current tester.
2.1.1. Carrying out measurements on the samples (sites) smaller or lesser thickness, and curved or plated surface subject to the influence of one of these factors. The necessary amendments are installing, as specified in the recommended application.
2.1.2. For the clad of control objects allowed measurements at stations with the remote cladding layer.
2.2. Parameter of roughness of the controlled surface must meet the requirements of operational documentation. In the absence of instructions, the roughness parameter should be no more than 40 µm according to GOST 2789.
2.3. On the test object at the measurement location are not allowed visible surface defects (shell, dents, nicks, cracks, corrosion damage, etc.).
2.4. The place of measurement should be cleaned from paint, sealant, glue, burnt rubber, oil, dirt, and other operational deposits and industrial pollution.
3. MEASUREMENTS
3.1. Measurement carried out at outdoor conditions that meet the requirements of the operational documentation of eddy current tester. Conditions of carrying out adjustment and measurement should be the same. The temperature of the test object and GSO should be the same, which is achieved by keeping them in the same temperature conditions.
3.2. The measurement of specific conductivity varicocoele gauges with an indicator device digital display or dial pointer widget in units of conductivity, is performed as follows.
Set up an eddy current meter, for two of the bonds from the set that have values of electrical conductivity, the most close to the limits of the band (sub-bands), or for two of the bonds, the conductivity of which is 2−5 MS/m is superior or inferior to the expected conductivity of the test object (), ensuring the coincidence of readings of eddy current measuring values of the electrical conductivity of the bonds.
For eddy current meter having a plurality of sub-ranges of measurement, adjustment is carried out for each sub-band.
Determine the conductivity of the test object on the digital display or dial pointer scale.
3.3. The measurement of specific conductivity varicocoele gauges with an indicator device, the dial pointer with a uniform scale, not widget, in units of electrical conductivity, is performed as follows.
Kit GSO choose the two nearest values of the standard sample having less () and more (
) the electrical conductivity compared to the conductivity of the testing object (
).
Compute the difference analog of the pointer in scale divisions for the two selected standard samples according to the formula
where is the deflection to the left from the starting position of the object of control (for example, from zero or from the Central division of the scale);
— the deflection to the right from the starting position.
Determine the scale dial pointer in MS/m by the formula
where and
is the conductivity of standard samples, with
less
.
For convenience, select a certain value of the scale division value of dial indicator (for example, using the correction sensitivity set the price of one division of the scale is equal to 0.1 or 0.01 MS/m).
The conductivity of the test object is calculated by the formula:
or
3.4. Allowed measurement of the electrical conductivity of the testing object varicocoele gauges with display unit in the form of a dial pointer, programmirovanie in units of electrical conductivity, according to the clause 3.3 (i.e. the method of comparison of the test object from GSO).
3.5. The results of the measurements draw up a Protocol or form of the product where it says:
grade;
type eddy current tester;
the name of the test object;
the value of electrical conductivity;
the date of the survey and the names of the operators;
the designation of this standard.
4. SAFETY REQUIREMENTS
4.1. When measuring the electrical conductivity eddy-current method should be guided by «Rules of technical operation of electrical installations» and"safety Rules at operation of electrical installations"*, approved by Gosenergonadzor.
_____________________
* There are «Interbranch rules on labor protection (safety rules) for electrical installations» (SWEAT P M-016−2001, RD 153−34.0−03.150−00). — Note the CODE.
4.2. Maintenance of eddy current meters that are powered from the mains AC voltage of 220 V, persons who have undergone training and passed the exam on the rules of the state energy supervision at the II qualifying group. The knowledge test operators on safe techniques and methods of work shall be held not less than once every 12 months.
4.3. Additional requirements and fire safety requirements established in the technical documentation for the control.
APPLICATION (recommended). THE DEFINITION OF THE AMENDMENTS IN THE MEASUREMENT OF THE ELECTRICAL CONDUCTIVITY OF THE OBJECT OF CONTROL TAKING INTO ACCOUNT THE INFLUENCE OF SIZE, SHAPE AND A PLATING LAYER
APP
Recommended
1. Determination of the value of correction of edge effect in the measurement of electrical conductivity
control objects have a small area for measurement
1.1. The adjustment value is determined using a set of samples of different diameter. The largest diameter end surfaces are 1.5−2 times exceed the requirements of operational documentation of eddy current tester. The diameter of the rest of the samples gradually reduced by 1−2 mm to the value, the smaller the required control size of 1−2 mm. Specimens made of one rod (one piece). The conductivity of the material should not differ from the conductivity of the testing object by more than 5%. Other sample requirements (thickness and roughness parameter) must comply with the operational documentation of eddy current tester.
For example, for control rods with a diameter of 12 mm at the end surface of the eddy-current tester, allowing to measure on the grounds of size 20x20 mm and 1 mm thick, it is recommended that a set of sample diameter from 10 to 30 mm (10, 11, 12, 14, 16, 18, 20, 30 mm), with thickness 1.5−2.0 mm.
1.2. For the correction of measured apparent electrical conductivity of the samples of different diameter with the end surface. Eddy-current transducer installed in the center of each sample.
1.3. The results of measurements of electrical conductivity build an experimental graph illustrating the effect of boundary effect, in the coordinates of the «Testimony of eddy current meter (apparent electrical conductivity) in MS/m — diameter end surfaces in mm» (hell.1).
Damn.1
Damn.1
1.4. The adjustment value in MS/m determined according to the schedule as the difference between the value of the electrical conductivity of the specimen the greatest diameter and the apparent conductivity of the sample with a diameter corresponding to the diameter of the controlled object.
1.5. The adjustment value is determined for each eddy current probe.
2. Determination of value of adjustment for thickness when measuring conductivity
thin-walled objects of control
2.1. The adjustment value is determined using a set of samples of different thicknesses or using the «speed» of the sample. Maximum thickness should be in 1.5−2 times exceed the requirements of operational documentation of eddy current tester. The thickness of the remaining samples is gradually reduced by 0.1−0.2 mm to the value, the smaller the required control size 0.1−0.2 mm. the Samples are made from a single sheet (one piece). The conductivity of the material should not differ from the conductivity of the testing object by more than 5%. Other sample requirements (size of the flat pad and the roughness parameter) must comply with the operational documentation of eddy current tester.
For example, to control sheets 0.7 mm thick eddy-current meter allowing to measure on the grounds of size 20x20 mm and 1 mm thick, recommends a set of samples with thickness from 0.5 to 2 mm (0,5; 0,6; 0,7; 0,8; 1,0; 1,5; 2,0 mm) size flat pad 30x30 mm.
2.2. For the correction of measured apparent electrical conductivity of the samples with different thicknesses.
2.3. The results of measurements build an experimental graph illustrating the effect of thickness, in the coordinates of the «Testimony of eddy current meter (apparent electrical conductivity) in MS/m — thickness of specimen in mm» (hell.2).
Damn.2
Damn.2
2.4. The adjustment value in MS/m determined according to the schedule as the difference between the value of the electrical conductivity of the sample of the largest thickness and apparent conductivity of the sample corresponding to the controlled object
(see the devil.2).
2.5. The adjustment value is determined for each eddy current probe.
2.6. Allowed to determine the conductivity of thin-walled objects of control (e.g., sheets) Assembly with an auxiliary plate or sheet of the same alloy, the total thickness of the test object and the plate shall be not less than specified in the operational documentation of eddy current tester. The amendment in this case is determined.
3. The determination of the meaning of the amendment on the thickness of the cladding layer in the measurement
the electrical conductivity of the clad objects of control
3.1. The adjustment value is determined using a set of samples with different thickness of cladding layer.
Samples made from a single sheet with double-sided plating of the desired alloy. To obtain the different thickness of cladding layer is etched samples. The thickness of the cladding layer is determined by metallographic method according to the current normative-technical documentation.
Other sample requirements (thickness, size of the flat pad and the roughness parameter) must comply with the operational documentation of eddy current tester.
3.2. For the correction of measured conductivity of each sample from two sides.
3.3. The results of measurements of electrical conductivity build an experimental graph illustrating the effect of thickness of the cladding layer, in the coordinates of the «Testimony of eddy current meter (apparent electrical conductivity) in MS/m, the thickness of a plating layer in microns» (hell.3).
Damn.3
1 — 
2 — 
Damn.3
The starting point (without plating) is taken as the arithmetic average of the conductivity of samples with replacerange side.
3.4. The adjustment value in MS/m determined according to the schedule as the difference between the value of the electrical conductivity of the sample without cladding coating and the apparent conductivity of the sample with an actual thickness of a plating coating
3.5. The adjustment value is determined for each eddy current probe.
4. The determination of the significance of amendments to the curvature of the surface when measuring
the electrical conductivity of the test objects of cylindrical shape
4.1. The values of corrections determined using a set of cylindrical samples of different diameter, made from a single blank.
The maximum diameter of the sample selected on the basis of requirements of operational documentation for eddy current tester for the surface curvature. The diameter of the rest of the samples gradually reduced by 10 mm to the value, the smaller the desired diameter of 5−10 mm. the roughness Parameter and the height (the linear size of the area of measurement) must comply with the operational documentation of eddy current tester.
The conductivity of the material should not differ from the conductivity of the testing object by more than ±5%.
4.2. Using GEO measure the conductivity of each sample of the set of flat and cylindrical surfaces. The results of measurements of electrical conductivity along the flat surface for sample labeling.
The transducer is set perpendicular to the cylindrical surface using a prism (Fig.4). Record the deflection of the indicator of eddy current meter in the direction of large values of conductivity or testimony digital scoreboard.
Damn.4
1 — testing object; 2 — eddy-current transducer meter
Damn.4
In measurements without installation in the prism allowed the rocking of the Converter, in this case, record the maximum deflection of the indicator or the maximum readings the digital display.
4.3. By measurements of conductivity of samples on the cylindrical surface build an experimental graph illustrating the effect of surface curvature in the coordinates of the «Testimony of eddy current meter (apparent electrical conductivity) in MS/m diameter in mm» (hell.5).
Damn.5
Damn.5
4.4. The adjustment value in MS/m determined according to the schedule as the difference between the actual value of conductivity
(see the marking on the cylindrical sample) and value of apparent electrical conductivity
of each sample with a diameter
defined by schedule:
4.5. Measure the apparent conductivity of the testing object on the cylindrical surface (see p.4.2).
4.6. The value of the electrical conductivity of the test object is determined by summing the results according to claim 4.5 results determine the value of the amendment (n.4.4) — eddy current for each meter separately.
An example of determining the electrical conductivity of the pipe diameter of 32 mm with a wall thickness of 2 mm of aluminum alloy using cylindrical samples with a conductivity of 18.4 MS/m.
Build an experimental schedule, as described in Chapter 4.3.
Determine the adjustment value for the curvature of the sample surface with a diameter of 32 mm, as specified in clause 4.4. According to the schedule value =17,0 MS/m.
Then =an 18.4 17.0 m=1,4 MS/m.
Measure the apparent conductivity of the tube along the cylindrical surface:
=16,2 MS/m.
Calculate the conductance of tubes with a diameter of 32 mm:
=16,2+1,4=17,6 MS/m.
The text of the document is verified by:
the official publication of the
Nondestructive testing.
Methods: a Collection of standards. -
M.: IPK Publishing house of standards, 2005
