Table 4

Limit errors in measuring angular dimensions

	Measurement error
1. Protractor mechanical	±(2 - 10)¢
2. Protractor optical	±20¢
3. Optical quadrant	±10¢ ¢
4. Square	±30¢ ¢
5. Bar levels, frame levels	Equal to the price of the division of the level
6. Micrometer levels	Too

APPENDIX 3

where h1 = h n- distance from element surface to the reference line at the first and last points of the considered section, equal to the height of the supports;

h i- the measured distance from the surface of the element to the reference line in i-th point of the considered section;

l i- distance from the first point of the considered section to i th points;

l n- distance from the first point of the considered section to the last ( n th);

dh1 and dh n- deviations from the conditional plane at the first and last points of the considered section.

1.2. For deviations dh1 and dh n for sections located along the perimeter of the marking, according to the formula (1), the corresponding deviations are taken dh I , dh II, dh III, dh IV at the corner marking points I, II, III, IV.

When drawing a conditional plane through the diagonal I - III parallel to the diagonals II - IV, take

where h 0(I-III), h 0(II - IV) - measured distances from the point of intersection of the projections of the diagonals on the surface of the element to the reference lines in the diagonal sections I - III, II - IV.

1.3. For deviations dh1 and dh n for all intermediate (transverse and longitudinal) marking sections in the formula (1) take the corresponding values dh i, calculated by formula (1) for sections located along the perimeter of the marking.

Example. The standard states that for a floor panel, the deviation from the flatness of the front surface should not exceed 10 mm, i.e. Dx= 10 mm.

Solution . To perform measurements, we determine (according to GOST 26433.0) the maximum measurement error

dx met = 0,2 Dx= 0.2 10 = 2.0 mm.

In accordance with Appendix 2, we accept the method of measuring with a string with readings on a ruler with millimeter divisions.

We mark the surface to be checked, taking a step between points equal to 1000 mm. Pulling the tape measure by hand, we apply risks on the surface with chalk through 1000 mm along the perimeter, in the center of the intersection of the diagonals, in longitudinal and cross sections; numbered in accordance with the marking of the surface point in the diagram (Fig. 1).

We install the string along the transverse and longitudinal sections and take readings at each point in the forward and reverse directions.

We record the results of observations in the protocol (Table 5) and calculate at each point the average values ​​from the readings taken in the forward and backward directions.

Table 5

	Point numberi	Distance from the reference line to the surface, mm			Deviations from the conditional plane, mm,dh i
		directly	back	mean
I-III
	0 (21)
	III
II - IV					3,0
	0 (21)
					3,0
I - II
					4,8
					2,5
					1,2
	5(II)				3,0
II-III					3,0
					0,2
					2,5
					2,2
III-IV
					2,8
					5,5
					5,2
					3,0
IV-I					3,0
					3,2
					1,5
					0,2
16 - 6					0,2
					3,9
					3,0
					0,9
					0,2
7 - 15					2,5
					4,2

GOST 26433.1-89

UDC 624.046006.354 Group Zh02

STATE STANDARD OF THE UNION OF THE SSR

System for ensuring the accuracy of geometric

parameters in construction

MEASUREMENT RULES

Prefabricated elements

System of ensuring geometrical

parameters accuracy in construction.

Rules of measure. Prefabricated elements

OKSTU 0021

Introduction date 1990-01-01

INFORMATION DATA

1. DEVELOPED by the Zonal Research and Design Institute for Standard and Experimental Design of Residential and public buildings(LenZNIIEP) State Committee for Architecture, Central Research and Design Institute for Standard and Experimental Design of Housing (TsNIIEP Housing) State Committee for Architecture, Central Research Institute for Standard and Experimental Design of Schools, Preschools, Secondary and Higher Educational Institutions ) State Committee for Architecture

INTRODUCED by the Zonal Research Institute for Standard and Experimental Design of Residential and Public Buildings (LenZNIIEP) of the State Committee for Architecture

PERFORMERS

L.N. Kovalis (head of the theme); G. B. Shoikhet, Candidate of Technical Sciences; A.V. Tsaregradsky; L.A. Wasserdam; D.M. Lakovsky; G.S. Mitnik, Candidate of Technical Sciences; V.V.Tishenko

2. APPROVED AND INTRODUCED BY Decree of the State Construction Committee of the USSR dated February 27, 1989 No. 32

3. REPLACE GOST 13015-75 in terms of measurement methods for reinforced concrete and concrete products

4. The standard takes into account all the provisions of the international standards ISO 7976/1 and ISO 7976/2 in terms of measurements of prefabricated elements

5. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

Designation of NTD, on	Number of paragraph, subparagraph, application
GOST 10-75
GOST 162-80
GOST 164-80
GOST 166-80
GOST 427-75
GOST 577-68
GOST 7502-80
GOST 8026-75
GOST 10528-76
GOST 10529-86
GOST 11098-75
GOST 13837-79
GOST 17435-72
GOST 21779-82
GOST 26433.0-85	one; 5, application 3
TU 3.824-78
TU 2-034-225-87

This standard establishes the rules for measuring linear and angular dimensions, shape deviations and the relative position of the surfaces of parts, products, structures and technological equipment manufactured at factories, construction sites and landfills.

1. General requirements for the choice of methods and measuring instruments, the performance of measurements and the processing of their results should be taken in accordance with GOST 26433.0.

2. To measure linear dimensions and their deviations, rulers are used according to GOST 427 and GOST 17435, tape measures according to GOST 7502, inside gauges according to GOST 10, staples according to GOST 11098, calipers according to GOST 166, depth gauges according to GOST 164, dial gauges according to GOST 577, probes according to TU 2-034-225 and microscopes of the MPB-2 type according to TU 3.824.

If necessary, special-made tools with reading devices in the form of dial indicators, micrometer heads and linear scales should be used: tape measures with a built-in dynamometer, length gauges, inside gauges, brackets and wedge probes.

3. To measure the deviations of the surface profile shapes, levels are used according to GOST 10528, theodolites according to GOST 10529 or straightedges according to GOST 8026 together with linear measuring instruments (rulers, indicators, calipers, etc.), as well as optical strings, sighting tubes, optical plane meters and hydrostatic altimeters according to current specifications. Means of special manufacture can also be used: control rails, plumb-rails, strings made of steel wire with a diameter of 0.2-0.5 mm or synthetic fishing line with a diameter of 0.8-1.0 mm.

4. Angular dimensions are checked with goniometers, and their deviations, expressed in linear units, with rulers and probes using squares, gauges, templates.

5. Depending on the material, dimensions and features of the shape of the elements, means not provided for by this standard can also be used to ensure the accuracy of measurements required by GOST 26433.0.

6. Schemes for measuring dimensions and their deviations, as well as deviations of shapes, are given in Appendix 1.

In this case, the correspondence of the real mutual position of the surfaces of the element (lines, axes) established requirements determined by measuring the corresponding linear and angular dimensions and their deviations. The position of openings, protrusions, inserts, embedded parts and other characteristic parts of the element is checked by measuring the dimensions indicated in the working drawings between these parts or between the parts and the faces (lines, points) of the element taken as the origin.

7. If in standards, specifications or working drawings do not establish the measurement locations for the dimensions of the element, then these locations are determined in accordance with this standard. The length, width, thickness, diameter, as well as angular dimensions or their deviations are measured in two extreme sections of the element at a distance of 50-100 mm from the edges, and if the length or width of the element is more than 2.5 m - and in its corresponding average section.

Deviations from straightness on the front surface of flat elements are measured in at least two any sections of the element, as a rule, in the direction of the light flux incident on this surface under operating conditions.

Deviations from the straightness of the side faces of flat elements are measured in one of the sections along each of the faces, and for cylindrical elements - along at least two generators located in mutually perpendicular sections.

Deviations from the straightness of the edge of the element are measured in sections along both surfaces forming this edge, at a distance of not more than 50 mm from it or directly at the intersection of these surfaces.

8. The values ​​of the limiting measurement errors that can be used when choosing methods and measuring instruments are given in Appendix 2.

9. Examples of determining deviations from flatness are given in Appendix 3.

Attachment 1

Measurement schemes

Table 1

Name of the measured parameter, method and measuring instrument	Scheme	Formulas for calculating the measured parameter
1. Linear dimensions and their deviations
1.1. Length, width, thickness of elements and their parts are measured:
a) between two fixed points
b) between a point and a straight line or a plane (between two straight lines or planes) by the wiggle method	Minimum count
c) between a point and a straight line or plane by constructing a perpendicular using a square
1.1.1. Direct size measurement:
a) a ruler		; (1) , (2) where - the value of the desired size, determined as a result of the measurement (actual size);
b) a tape measure with manual tension (at a distance of not more than 10 m) or a dynamometer. If there are defects in the measurement sites that interfere with the removal of readings, leveling devices are used.		nominal size; Actual deviation; Initial and final readings on the scale of the measuring instrument
c) caliper
d) length gauge with a device for installing and fixing on the product the end of the tape measure with the initial count Note. The difference in thickness is defined as the difference between the largest and smallest of the measured values ​​of the thickness of one product.		Too
1.1.2. Direct measurement of deflection with measuring instruments adjusted to the nominal size:		at , ; , (3) where is the initial reading corresponding to the nominal size; set to zero or another value when setting up the instrument for measurement
a) caliper
b) staple
c) a length gauge with the determination of the deviation on a scale with a vernier
d) dial indicator installed on the stand
1.2. Diameter
1.2.1. Direct measurement of the diameter by swinging with a tape measure, ruler, caliper		where is the maximum count of the possible counts
1.2.2. Direct measurement of deviation by swinging with a clamp, inside gauge set to the nominal size
1.2.3. Indirect diameter measurement:		(4)
a) by girdling with a tape measure
b) the method of measuring the chord and height of the segment with a caliper with measurement limits of 320-1000 mm Note. Out-of-roundness is defined as the difference between the largest and smallest of the measured diameters in one cross section.		(5) where is the length of the chord, Segment height (known or measured with known
1.3. Distances between points (axes) located on different faces of the element
1.3.1. Direct measurement of the size with tape measures, rulers:
a) the method of projecting one of the points (axes) onto the measurement line using markings
b) the method of designing two points on the measurement line using squares, plumb lines or optical plummets	1 - measurement line
1.3.2. Indirect measurement of deviation of a point from the axis with a ruler by projecting a point onto a measurement line using a square or marking		(6) , (7) where and are dimensions obtained by direct measurement
1.4. center distance		a) (8)
1.4.1. Indirect measurement with ruler, caliper, tape measure		b) (9) where and are the dimensions obtained by direct measurement
1.5. Length, width and depth (height) of cracks, gaps, shells, rims, sagging
1.5.1. Direct measurement of length, width:
a) a ruler
b) microscope
c) palette (transparent plate measuring 200x200 mm with a grid of squares 5x5 mm)		K is the number of shells squared K = 3, mm
d) probe
1.5.2. Direct measurement of depth, height with caliper ШЦ-1
1.5.3. Indirect ruler measurement
2. Angular dimensions and their deviations
2.1. Direct measurement angular size goniometers
2.2. Direct measurement of the deviation of the angular size in a linear measure over a length L with a square with a ruler or a probe (deviations from perpendicularity, cut obliqueness, etc.)	1 - tested product; 2 - square; 3 - probe, end measure, ruler
3. Deviations in the shape of the profile or surface * (straightness and flatness, including waviness, deflection, convexity, concavity, etc.)
____________ * Obtained by measurements according to this standard, the values ​​of deviations from straightness and flatness are compared with the corresponding tolerance.
3.1. Deviations from straightness
3.1.1. Determination of the deviation from straightness over the entire length of the element using a string on supports of equal height, which sets the reference line, and a ruler. The mass of the suspended load for a metal string with a diameter of 0.2-0.5 mm for a length of up to 20 m is not less than 10 kg; for a nylon string with a diameter of 0.8 - 1.0 mm for a length of up to 20 m - at least 2 kg	1 - checked surface; 2 - string; 3 - supports for string tension; 4 - conditional straight line; 5 - ruler for reading	Straightness deviation are taken equal to: the sum of the absolute values ​​of the largest of all positive and the largest of all negative deviations measured at various points if they have different signs; the largest in absolute value of all measured deviations if they have the same signs
Measurements are carried out at points marked on the surface of the element in an amount determined depending on the length of the product		(10) where is the distance from the reference line to the tested surface at the support points; The same, at intermediate marking points
3.1.2. Determining the deviation from straightness in the section of the element using a straightedge or control rail on supports of equal height that set the reference line, and a ruler, indicator or probe	1 - checked surface; 2 - calibration ruler, rail; 3 - reference prism; 4 - conditional straight line; 5 - reference line; 6 - indicator	Too When installing the control rail directly on the surface of the product
3.1.3. Determination of the deviation from straightness along the entire length of the element using a level or theodolite that sets the reference line and a ruler. The accuracy of the position of the tested surface relative to the reference line is not regulated	2 - level; 3 - reference line; 4 - conditional straight line; 5 - ruler	(11) where are the distances between the initial and final and initial and intermediate marking points, respectively; with an equal marking step and equal to the corresponding number of steps
3.2. Flatness deviations
3.2.1. Determination of the deviation at the corner point of a rectangular element relative to the conditional plane drawn through three other corner points (propeller or twist):
a) the method of direct measurement with a ruler or wedge probe of the deviation at the corner point of an element installed on four supports located in the same plane (conditional)
b) the method of measuring the distances from each of the four corner points of the element to the reference plane with the subsequent calculation of the deviation from the conditional plane with a ruler. Depending on the position of the element, the reference plane is set horizontally with a level or vertically with a theodolite or two plumb lines (plummet-rails). The accuracy of the position of the element relative to the reference plane is not regulated and is determined by the length measuring ruler	1 - plumb; 2 - scale for reading	(12) At (13)
3.2.2. Determination of deviation from the conditional plane over the entire surface of the element:		The deviation from flatness is taken equal to the largest result of the measurements at the fourth corner point and at the point of intersection of the diagonals.
a) the method of direct measurement with a dial indicator or a probe of the deviation of the surface from a conditional plane drawn through three points	1 - measurement object; 2 - calibration plate; 3 - probe, indicator	Indicators are set to zero counting by surface plate
b) the method of measuring the distance from the points marked on the surface of the element with a ruler to the reference line given by a string, a straightedge or a control rail on supports of equal height, installed at the marked points along the edges of the element. The points at which measurements are made are located on the controlled surface at the intersection of the longitudinal and transverse sections of the element at the rate of 4-10 sections on each side, depending on the size of the element, as well as at the intersection of the projections of the diagonals on the surface of the element	1 - checked surface; 2 - string; 3 - ruler; 4 - supports for string tension	Flatness deviation are taken equal to:
c) the method of measuring with a ruler the distances from the points marked on the surface of the element to the reference plane set horizontally by a level or vertically by a theodolite. The points at which measurements are made are located on the controlled surface at the intersection of the longitudinal and transverse sections of the element at the rate of 4-10 sections on each side, depending on the size of the element. The accuracy of the position of the element relative to the reference plane is not regulated and is determined by the length of the measuring ruler	1 - checked surface; 2 - ruler; 3 - level	Flatness deviation are taken equal to: the sum of the absolute values ​​of the largest of all positive and the largest of all negative deviations at marked points, if they have different signs; the largest in absolute value of all deviations if they have the same sign. Formulas and an example of calculating deviations at each of the marked points from the conditional plane drawn through one of the diagonals parallel to the other diagonal, are given in Appendix 3.
3.3. Deviations from a given profile or surface complex shape Measurements are made at points and intersections marked on the surface of the element, characteristic of the controlled surface of longitudinal and transverse (radial and circular, etc.) sections		The deviation of the real profile from the design one is taken equal to the largest of all measured values ​​of the gap in the controlled section
3.3.1. Direct measurement with a ruler, indicator or probe of deviations of the real profile from the template	1 - checked surface; 2 - template; 3 - reference line; 4 - probe; 5 - sections in which the template is installed; 6 - marking points on the template, in which the gap is measured
3.3.2. Determination of deviations from the design values ​​of the actual coordinates of the characteristic points of the real surface of the element installed in the working position. Measurements are made by direct or indirect methods using a level and staff or string and ruler, hydrostatic altimeter, etc.		(19) where is the actual value of the coordinate; Nominal value of the coordinate; The distances corresponding to the nominal values ​​of the coordinate are marked from the point taken as the origin of coordinates along the horizontal axis

APPENDIX 2

Reference

Limit measurement errors

Limit measurement errors using the recommended measuring instruments are given in Table. 2-4 and calculated for air temperature = (20 ± 8)°C and temperature difference between the object and the measuring instrument equal to 2°C. The tension of the roulette is carried out manually.

table 2

Limit errors in measuring linear dimensions

	Limit measurement errors, mm
Nominal intervals dimensions, mm	Vernier instrument, vernier reading 0.1 mm	Inside gauges, staples, reading value by indicator, micrometer, vernier 0.01 mm	Metal rulers, scale division 1.0 mm	Caliper, chord method and segment height	Roulettes of the 3rd class, division value 1.0 mm	Length gauges, vernier reading 0.1 mm
St. 1 to 50	0,1		0,4
" 50 " 200	0,2	0,02	0,4
" 200 " 500	0,2	0,03	0,5	0,6	0,5*
" 500 " 1000	0,3	0,05	0,5	1,0	0,5*;0,5**
" 1000 " 4000	0,5	0,2		1,4	1,5*;1,0**	0,8
" 4000 " 6000		0,3		2,5	2,0*;1,5**	1,0
" 6000 " 10000		0,4		4,0	2,5*;2,0**	1,5
" 10000 " 16000					3,5*	2,5
" 16000 " 25000					4,5*	3,0

_____________

* The errors of measurement of lengths and diameters are given.

** Errors in measuring diameters by the girdling method.

Table 3

Limit errors of measurement of shape parameters and

relative position of surfaces

	Limit measurement errors, mm
Nominal intervals	Straightedge		Rail	String metal or kapron		Optical string, plane meter, spotting scopes type	Level		Theodolite	Measuring instruments of special production
dimensions, mm	counting down					PPS, hydrosta-	H05	H-3, NZK	T-2, T5
	indie	whether-	whether-	micro-	whether-	tic
	Kator	neike	neike	Osprey	neike	level, microni-velir,	Countdown on a ruler with a division price 1.0 mm			NPL-1	NPR-1
	with division value, mm					level
	0,01	1,0	1,0	0,01	1,0
Up to 100										0,02	0,02
St. 100 to 200
" 200 " 1000	0,08	0,4	0,4			0,01
" 1000 " 2000	0,08	0,4	0,4	0,05	0,3	0,02
" 2000 " 3000	0,15	0,4		0,1	0,4	0,03		0,5	1,0
" 3000 " 5000				0,1	0,4	0,05		0,5	1,0
" 5000 " 8000				0,2	0,4	0,06	0,2	0,8	1,0
" 8000 " 10000				0,2	0,5	0,1	0,2	0,8	1,0
" 10000 " 20000				0,3

Approved by order of the Federal Agency for Technical Regulation and Metrology dated November 8, 2012 N 699-st

National standard of the Russian Federation GOST R 55042-2012

"NON-DESTRUCTIVE TESTING. DETERMINATION OF THE THICKNESS OF METAL COATINGS BY ACOUSTIC METHOD. GENERAL REQUIREMENTS"

non-destructive testing. Evaluation of metallic coating thickness by ultrasound. General requirements

Introduced for the first time

Foreword

Goals and principles of standardization in Russian Federation established by the Federal Law of December 27, 2002 N 184-FZ "On Technical Regulation", and the rules for the application of national standards of the Russian Federation - GOST R 1.0-2004 "Standardization in the Russian Federation. Basic provisions"

About the standard

1 Developed by Autonomous non-profit organization"Research Center for Control and Diagnostics of Technical Systems" (ANO "NITs KD"), Nizhny Novgorod Branch of the Federal State budget institution Science Institute of Mechanical Engineering. A.A. Blagonravov of the Russian Academy of Sciences (NF IMASH RAS)

2 Introduced by the Technical Committee for Standardization TK 132 "Technical Diagnostics"

3 Approved and put into effect by order of the Federal Agency for Technical Regulation and Metrology dated November 8, 2012 N 699-st

4 First introduced

Introduction

Almost all industries use various metal coatings applied to the surface of technical objects. In cases where coatings are applied to the surface of potentially hazardous technical objects, increased requirements are imposed on the permissible error in the thickness of the coatings. This applies to hardening and, in particular, to restorative coatings.

In accordance with GOST 27750, the determination of the coating thickness is carried out by the following methods: magnetic (magnetic flux method, ponderomotive method and induction method), eddy current, thermoelectric and ionizing radiation.

The main disadvantage of magnetic methods is the requirement for a sharp difference in the magnetic properties of the base materials (it must be ferromagnetic) and the coating, which is far from being fulfilled in all cases.

The eddy current method has received the greatest application for determining the thickness of non-metallic coatings on a base of non-ferrous metals. When used to determine the thickness of coatings deposited on bases made of ferrous metals with non-normalized electrical resistance, an unacceptably large error occurs.

The thermoelectric method has a high error, which does not allow it to be used to determine the thickness of element coatings on the surface of critical technical objects, and the ionizing radiation method is not widely used due to increased safety requirements.

This International Standard has been developed to provide a methodological basis for the application of the acoustic method for determining the thickness of metallic coatings on metal bases for any combination of magnetic and electrical properties of coating and base materials.

1 area of ​​use

This International Standard covers an acoustic method for determining the thickness of metallic coatings on metallic substrates.

The standard establishes the basic requirements for the procedure for determining the thickness of coatings using Rayleigh surface acoustic waves propagating along the surface of the test object with applied metal coated with good adhesion to the base material.

The method established by the standard can be applied both in laboratory research and in the operation of technical objects for various purposes.

2 Normative references

This standard uses Normative references to the following standards:

GOST 8.362-79 State system ensuring the uniformity of measurements. Coating thickness measurement. Terms and Definitions

GOST 9.008-82 one system protection against corrosion and aging. Metallic and non-metallic coatings

GOST 12.1.001-89 System of labor safety standards. Ultrasound. General requirements security

GOST 12.1.004-91 Occupational safety standards system. Fire safety. General requirements

GOST 12.1.019-79 Occupational safety standards system. Electrical safety. General requirements and nomenclature of types of protection

GOST 12.1.038-82 Occupational safety standards system. Electrical safety. Maximum allowable values ​​of touch voltages and currents

GOST 12.2.003-91 Occupational safety standards system. Production equipment. General safety requirements

GOST 12.2.013.0-91 Occupational safety standards system. Machines manual electric. General safety requirements and test methods

GOST 12.3.002-75 Occupational safety standards system. Manufacturing processes. General safety requirements

GOST 32-74 Turbine oils. Specifications

GOST 2768-84 Technical acetone. Specifications

GOST 2789-73 Surface roughness. Parameters and characteristics

GOST 6259-75 Reagents. Glycerol. Specifications

GOST 6616-94 Thermoelectric converters. General specifications

GOST 6651-94 Resistance thermal converters. General technical requirements and test methods

GOST 17299-78 Technical ethyl alcohol. Specifications

GOST 26266-90 Non-destructive testing. Ultrasonic transducers. General technical requirements

GOST 27750-88 Non-destructive testing. Restorative coatings. Coating Thickness Control Methods

NOTE When using this standard, it is advisable to check the validity of the referenced standards in information system general use - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annually published information index "National Standards", which is published as of January 1 of the current year, and according to the corresponding issues of the monthly published information index "National Standards", published in current year. If the reference standard is replaced (modified), then when using this standard, you should be guided by the replacing (modified) standard. If the referenced standard is canceled without replacement, the provision in which the reference to it is given applies to the extent that this reference is not affected.

3 Terms, definitions, symbols and abbreviations

3.1 This standard uses the terms and definitions according to GOST 8.362 and GOST 9.008.

3.2 The following symbols are used in this standard:

V o - propagation velocity of surface acoustic Rayleigh waves in the base material, km/s;

V n is the propagation velocity of Rayleigh surface acoustic waves in the coating material, km/s;

h - coating thickness, microns;

∆h o - maximum permissible absolute error in determining the coating thickness, microns;

f e - effective pulse frequency of Rayleigh surface acoustic waves, MHz;

t i is the result of a single measurement of the Rayleigh surface acoustic wave pulse delay in the area of ​​the selected coating measurement point;

N is the number of measurements of the Rayleigh surface acoustic wave pulse delay in the area of ​​the selected coating measurement point;

Average delay of the Rayleigh surface acoustic wave pulse in the area of ​​the selected coating measurement point, ns;

t n is the reduced delay of the impulse of the Rayleigh surface acoustic wave in the zone of the selected measurement point of the coverage, ns;

T is the temperature at which the delay was measured, °С;

Average delay of the Rayleigh surface acoustic wave impulse in the base material of a metal structural element, ns;

is the reduced delay of the Rayleigh surface acoustic wave pulse in the base material, ns;

T 0 - temperature at which the delay was measured, °C;

λ is the length of the Rayleigh surface acoustic wave in the coating material, µm;

k T - thermoacoustic coefficient equal to the relative change in the delay of the Rayleigh wave pulse when the temperature changes by 1°C, 1/°C.

3.3 The following abbreviations are used in this standard:

TP - coating thickness;

SAVR - Rayleigh surface acoustic wave;

PEP-piezoelectric transducer;

SI is a measuring instrument.

4 General provisions

4.1 The method is based on the fact that at different speeds of surfactant propagation in the coating and base materials, the effective surfactant velocity in a structural element with a thin (up to 100 microns) coating depends on TP - .

4.2 The method is implemented using manual method ultrasonic contact sounding using separate-combined probes according to GOST 26266.

4.3 Optimal view emitted signal - "radio pulse" with high-frequency (ultrasonic) filling, smooth envelope and effective duration (at the level of 0.6 maximum amplitude) 2 - 4 periods of the fundamental frequency.

4.4 The determined TP is averaged along the path of the PAVR impulse propagation.

5 Safety requirements

5.1 To perform measurements, allow operators who have the skills to operate ultrasonic testing equipment, who are able to use national and industry regulatory and technical documents on acoustic control methods, trained to work with the applied measuring instruments and certified for knowledge of safety rules in the relevant industry.

5.2 When determining the TP, the operator must be guided by GOST 12.1.001, GOST 12.2.003, GOST 12.3.002 and the technical safety rules for the operation of consumer electrical installations in accordance with GOST 12.1.019 and GOST 12.1.038.

5.3 Measurements are carried out in accordance with the safety requirements specified in the operating instructions for the equipment included in the used MI.

5.4 Premises for measurements must comply with the requirements for and.

5.5 When organizing work to determine the TP, the requirements fire safety according to GOST 12.1.004.

6 Requirements for measuring instruments

6.1 As MI, installations assembled from serial equipment or specialized ultrasonic devices (hereinafter referred to as devices), certified and verified in the prescribed manner, are used.

6.2 MI should provide a relative error in determining the delay of the PAVR pulse no more than 10 -4 .

6.3 Performance characteristics devices must comply with the requirements of the technical specifications and this standard.

6.4 Separate-combined piezoelectric transducers of the P122 type according to GOST 26266 are used as a probe, consisting of an emitter and a receiver of longitudinal waves combined in one housing.

6.5 To measure the surface temperature of the coating, contact thermometers are used according to GOST 6651 or according to GOST 6616 of the "TK" type with a temperature measurement error of not more than 1°C in the temperature range from 0°C to 60°C.

6.6 Auxiliary devices and materials

6.6.1 Grinding tool for preparing the surface of the coating - according to GOST 12.2.013.0.

6.6.2 To degrease the surface, use alcohol according to GOST 17299 or acetone according to GOST 2768.

6.6.3 As contact fluid rather thick liquids that conduct ultrasound well are used (for example, glycerin according to GOST 6259; autols 6, 10, 18; compressor and other oils similar to it according to GOST 32, which have wetting properties with respect to the coating surface and the contact surface of the probe).

7 Coating requirements

7.1 The coating must be free from cracks, chips, delaminations, swellings, open and closed shells, and surface contamination.

7.2 TP should be greater than the microroughness of the surface of the base material.

7.3 As a base material, magnetic and non-magnetic materials can be used: steels and iron-based alloys; alloys based on copper, aluminum, titanium, nickel, etc.

7.4 The surface roughness of the coating is according to GOST 2789 and must comply with the design documentation.

Note - The method does not provide the required accuracy of determining the thermal conductivity, if the surface roughness of the coating Ra exceeds 2.5 µm according to GOST 2789.

7.5 The thickness of the base in the measurement area must be at least 2 mm.

7.6 The surface temperature of the coating in the measurement zone should be in the range from 0°С to 60°С.

7.7 Before installing the probe, the surface of the coating is cleaned of dirt, scale, rust and degreased.

8 How to prepare for measurements

8.1 Establish the maximum permissible absolute error in determining the TP ∆h o .

8.2 Choose a probe, the effective pulse frequency of which, depending on ∆h o, has the following values:

At f e = 2.5 MHz ∆h o = ± (1 - 2) µm;

At f e = 5.0 MHz ∆h o = ±(0.5 - 1) µm;

At f e = 10 MHz ∆h o = ± (0.25 - 0.5) µm.

8.3 On the basis of reference data or experimentally determine the values ​​of V o , V n , .

8.4 Determine the location of the TP measurement points.

8.5 The dimensions of these zones should be one and a half times or more than the corresponding dimensions of the contact surface of the probe.

8.6 Apply a layer of couplant to the prepared surface of the coating.

8.7 Turn on the device, check its performance by displaying the time base of the received signals on the screen of the video monitoring device.

8.8 Check the absence of pulses on the time base caused by the presence of additional reflective boundaries (cracks, scratches, etc.) in the measurement area.

9 Order of measurements and rules for their processing

9.1 Measure the surface temperature of the coating in the zones of the selected measurement points.

9.2 In the selected zones, measure the delays of the PAVR pulses and record their results.

9.3 The measurements according to 9.2 are repeated 3 to 5 times.

9.4 For each zone, the average values ​​of the delays of the PAVR pulses are determined by the formula

9.5 Calculate the coefficient of variation of the results of measurements of the delays of the STA pulse according to the formula

where σ t is the standard deviation calculated by the formula

.

9.6 If the ratio δ≤10 -4 is met, then the resulting value is chosen as the calculated value of the SHRD pulse delay, otherwise the number of measurements N is increased and the measurements according to 9.2 - 9.5 are repeated until the value of the coefficient of variation δ reaches the value 10 - four .

Note - If it is impossible to ensure the value of the coefficient of variation δ is not more than 10 -4, a decision is made to determine the TP with reduced accuracy or the impossibility of measurements.

9.7 Calculate the reduced delays t° and using the formulas

,

.

Note - For the most common base metals and coatings and a transducer prism made of plexiglass, the value of k T can be taken equal to 2.3 10 -4 1/°C. With increased requirements for the accuracy of determining the TP, the value of k T is determined experimentally.

9.8 TP in each measurement zone is calculated by the formula

.

10 Rules for reporting measurement results

10.1 The measurement results are recorded in the protocol, the form of which is given in Appendix A.

Measurement protocol form

"APPROVE"

Supervisor

_____________________________

name of company

_____________ ________________

personal signature initials, surname

"______" _________20_____

PROTOCOL

coating thickness determination

______________________________________________________________________________________

(technical facility, controlled area technical object)

1 Date of measurement ________________________________________________________________________

2 Organization conducting measurements _________________________________________________

3 Owner of the object __________________________________________________________________________

4 Object data:

appointment ____________________________________________________________________________

manufacturer, manufacturing technology of the object ___________________________________

thickness of the base in the area of ​​the measuring point ______________________________________________

surface condition of the coating __________________________________________________________

additional information about the object __________________________________________________________

5 Sketch of the object indicating the location of the measurement zones and their numbering (given in

annex to the protocol) ________________________________________________________________

6 Information about the materials of the object:

Manufacturer country___________________________________________________________________

grade of material (indicating national or other standard) _______________________

manufacturing technology_______________________________________________________________

7 Effective frequency of the SAW pulse (MHz) _______________________________________________

8 Coating surface temperature (°С)_______________________________________________

9 Highest value the coefficient of variation of the PAVR pulse delays ____________________

Table 1 - Results of measurements in zones

______________ _________________

Measurements were performed by the operator personal signature initials, surname

Laboratory manager ______________ __________________

non-destructive testing personal signature initials, surname

Bibliography

This International Standard specifies methods for measuring the thickness of organic coatings applied to a surface to be coated. This standard does not apply to metallic coatings. Some of the above methods can be applied to measure the thickness of free films. Methods, their areas of application and measurement accuracy are given in.

This International Standard is applicable to the determination of the thickness of paint coatings by the following methods:

No. 3 - Measurement of the thickness of the dried coating with instruments using mechanical contact;

No. 6 - Magnetic method;

No. 7 - Eddy current method.

The standard contains definitions of terms related to the technique of measuring the thickness of coatings.

In this standard Additional requirements reflecting the needs of the country's economy are in italics.

2 Normative references

This standard uses references to the following standards:

GOST 8.362-79 State system for ensuring the uniformity of measurements. Coating thickness measurement. Terms and Definitions

GOST 2789-73* Surface roughness. Parameters and characteristics

GOST 8832-76* (ISO 1514-84) Paintwork materials. Methods for obtaining a paint coating for testing

Methods for measuring the thickness of coatings

Table 1

Method number and name	Measuring instrument and scope	Intrinsic error* and measurement accuracy	Note
No. 1 - Determining the thickness of the wet layer	A. Calibrated comb		Measurements give an approximate value for the wet layer thickness
	B. Wheel thickness gauge	Accuracy ±2.5% + 1 µm	The method can be used in the laboratory and at the staining site
	C. Weighing to measure the thickness of the wet layer on a freshly painted surface	Reproducibility ±15 µm	Method No. 1C can also be used to determine the thickness of the dried coating, but only in the laboratory.
No. 2 - Determining the thickness of the dried coating by calculating the ratio between the mass and the area of ​​the dried coating	Used for soft coatings, the thickness of which cannot be measured with instruments with clamping elements or a measuring rod	Measurements give inaccurate results	Provides a check when the thickness value is within the specified limits. Coating remains intact
No. 3 - Measuring the thickness of the dried coating with instruments using mechanical contact	A. Micrometric method. Used for measurements on almost flat plates and painted surfaces	Accuracy ±2 µm. Reproducibility ±30% - for thin coatings; ±20% - for thick coatings	The coating must be hard enough to withstand the indentation force upon contact with the jaws of the micrometer. The coating is destroyed during the test. If the film is not separated from the substrate, the coating thickness should be more than 25 µm
	B. Method using a multi-turn indicator. Test plates or painted surfaces shall be substantially flat or curvature in one direction.	Reproducibility ± 10% with a lower limit of 2 µm	The coating must be hard enough to withstand the pressing force on contact with the dipstick.
No. 4 - Measurement of the thickness of the dried coating by profilometric method			The coating must be hard enough to withstand the indentation force of the profilometer pen. The coating is destroyed during the test
No. 5 - Measuring the thickness of the dried coating using a microscope	A. Microscopic examination of the cross section. Recommended as a referee measurement method for coatings on substrates with complex profiles, such as shot blasted surfaces	Accuracy ± 2 µm. Reproducibility ±10%	A section of the painted product is cut out and fixed on the resin. The coating is destroyed during the test
	B. Wedge cutting method. The method is not applicable to fragile and loose coatings. Methods A and B can be used to determine the thickness of individual layers in a multilayer coating	Repeatability ±10% with a lower limit of 2 µm	To cut the film, you need a special cutting tool or drill. The coating is destroyed during the measurement
	C. Surface profile measurement method. For use on clear coatings and coatings that can easily peel off the substrate.	Reproducibility ±10%	A special microscope (light section microscope) is used to study the coating profile. Transparent coatings are not destroyed
No. 6 - Magnetic Methods	For magnetic metal bases:
	A. Magnetic induction principle	Accuracy ±2% + 1 µm.Reproducibility ±10%	The coating must be hard enough to withstand the pressure of the sensor.
	B. Permanent magnet pull-off principle	Accuracy ±5% + 1 µm	Measurements can be taken at the staining site
No. 7 - Eddy current method	For non-magnetic metal substrates	Accuracy ±2% + 1 µm Repeatability ±10%	The devices operate on the principle of eddy currents. The coating must be hard enough to withstand the pressure of the sensor. Measurements can be taken at the staining site
No. 8 - Non-contact methods	Used when tool-to-coated contact is undesirable. Used for measurements on almost flat painted surfaces	Reproducibility ±10%	The devices use the principle of backscattering.b-particles (method No. 8A) or X-ray fluorescence phenomenon (method No. 8B). Coatings must be homogeneous for accurate results.
No. 9 - Gravimetric (dissolution) method	Used to measure the thickness of coatings on substrates with a non-uniform profile (for example, steel plates after shot-blasting) and for coatings on polymer substrates, if the latter are not exposed to paint thinners		The weight of the coating is measured by dissolving the coating without dissolving the base. The average value of the coating thickness is determined by dividing the value of the mass of the coating by the density and area of ​​the coating
No. 10 - Determination of the thickness of the dried coating on steel substrates subjected to shot blasting	For dried coatings on magnetic metal substrates with a rough surface (after shot blasting)		The devices use the phenomenon of magnetic induction. Measurements can be taken at the staining site. In some cases, Method No. 5A or Method No. 9 may also be used.
*Uncertainties are taken from the instructions of the respective industrial devices. Note - Some of the methods listed in the table can be used to measure free film thickness.

3 Additional Information

For each specific measurement method specified in this International Standard, the following Additional Information, which should be taken from an international standard or a national standard, or other document relating to the material being tested, it should, if possible, be the subject of an agreement between the parties concerned:

The method of applying the material to the surface to be painted and an indication of the number of layers;

Single-layer coating or multi-layer paint system;

Duration and conditions of drying (natural or hot), aging of coatings (if any) before measurement;

Coating thickness measurement method ();

Responsible area of ​​the stained sample and, if necessary, the number of measurements.

4 Definitions

For the purposes of this International Standard, the following terms apply with their respective definitions:

4.1 coating thickness: The distance between the surface of the coating and the surface to be painted.

Note - The value of the coating thickness depends to some extent on the chosen measurement method. An accurate result is possible if the surface to be painted and the surface of the coating are even and smooth. In practice, neither the surface to be painted nor the surface of the coating is smooth. In many cases, the roughness exceeds 10% coating thickness. This roughness affects the measurement results obtained various methods. For each method, this influence has its own specific features. Therefore, the results of measurements of the same sample, performed different methods, can differ significantly from each other. The results of coating thickness measurements should be accompanied by an indication of the method of measurement, the type of instrument used and, if known, the uncertainty.

4.2 responsible part of the surface: A part of a painted or to be painted article for which the coating plays an essential role in its function and/or decorative appearance.

4.3 control area: The section of the critical part of the surface within which the required amount individual measurements.

4.4 measuring point: The location where a single measurement is made. In this standard, the measuring point (test location) is determined depending on the measurement method as follows:

For gravimetric methods (dissolution) - the place where the coating is removed;

For microscopic examination methods, the place where a single measurement is carried out;

For non-destructive methods, the area occupied by the probe, or area of ​​the surface that affects the readings of the instrument.

4.5 local coating thickness: The average value of the results of a certain number of measurements taken within a given control area.

4.6 smallest local thickness: The smallest value of the local thickness on the critical part of the surface of this product.

4.7 greatest local thickness: The largest value of the local thickness on the critical part of the surface of this product.

4.8 average thickness: The arithmetic mean of the test results of a given number of local thickness measurements evenly distributed over the critical part of the coating, or the result of a gravimetric thickness determination.

4.9 wet layer thickness: The thickness of the coating material layer, measured immediately after application.

5 General requirements

5.1 Fundamentals

This standard provides information on the number and location of measurement points when determining the thickness of the paintwork on standard test plates prepared in accordance with GOST 8832-76*. On other surfaces to be coated and painted products, the number and arrangement of measurement points must be chosen in such a way that the measurements result in reproducible coating thickness values. The choice of these conditions should be the subject of an agreement between the parties concerned.

The manufacturer's instructions must be followed when using the instruments.

Instruments should be checked for reproducibility. Regularly calibrate the instrument and check the condition of the probe tip.

Make sure that the probe tip pressure does not significantly affect the measurement results.

5.2 Surface roughness

The roughness of the surface to be painted affects the determination of the thickness of the coating. Using optical methods it is recommended to specify control lines or sections in advance.

In the case of using a non-destructive testing method, the calibration of the instrument should be carried out on the same surface that is used for testing in a painted form.

For steel bases that have undergone shot blasting, apply special conditions(method number 10).

5.3 Edge effect

The readings of some instruments are affected by the presence of edges on the sample. There are instruments that can be calibrated in such a way that they take into account the edge effect. Measurements are carried out at a distance of more than 25 mm from the edge of the product or sample, or at such a distance from the edge for which the device is calibrated.

5.4 Surface curvature

Some instruments are sensitive to surface curvature, so they must be calibrated on surfaces with the same curvature as the specimens to be tested.

6 Method No. 3 - Measuring the thickness of the dried coating with instruments using mechanical contact

Measurements are made on coatings dried to such an extent that they can withstand the action of the clamping elements of the micrometer or the measuring rod of the multi-turn indicator without visible damage.

This method is suitable for flat painted surfaces and products, as well as products with a circular cross section (eg wire) and for coatings that can be removed by solvent or mechanical means.

6.1 Method No. 3A - Measurement of coating thickness by micrometric method

6.1.1 General

This method makes it possible to measure the thickness of the dried coating with measuring instruments with a measurement error limit of 5 µm.

6.1.2 Measuring instruments

Any micrometer equipped with a ratchet, with a measurement error limit of 5 µm or less ().

6.1.3 Test procedure

6.1.3.1 Select the points at which measurements are to be taken. The measurement points must be free from surface defects and located at least 20 mm from the edge of the paintwork at a distance of ≈ 50 mm from each other.

When working with large painted surfaces, the number of measurement points and their location on the surface should be such as to obtain reliable data characterizing the coating thickness over the entire painted area.

A circle with a diameter of ≈ 10 mm is drawn around each measurement point with light pressure and a serial number is placed next to it.

6.1.3.2 The painted sample is fixed so that all test points are available for measurement with a micrometer ().

6.1.3.3 The micrometer is positioned so that the heel of the micrometer is in contact with reverse side sample to be measured directly below the first measuring point. Slowly rotating the drum of the micrometric screw, the measuring rod is moved to the starting point to failure, while the measuring rod does not move further when the ratchet is turned.

Record the micrometer readings, using a mirror if necessary. The measurement results are entered into the protocol along with the number of the measurement point.

Loosen the clamps, remove the micrometer and repeat the whole procedure at the next measurement point.

6.1.3.4 Carefully remove the coating within a circle at each measurement point with an appropriate solvent or mechanically, being careful not to erase the number. To do this, the test area is covered with a round piece of filter paper and a few drops of the appropriate solvent are applied to it.

Measure the base thickness by repeating the procedures for each measurement point.

Note - The thickness of the base can be measured before painting, so as not to violate the integrity of the coating later.

6.1.4 Handling results

6.1.4.1 Calculate the thickness of the coating at each measurement point by subtracting the readings obtained after the removal of the coating from the readings obtained before it.

6.1.4.2 Calculate the arithmetic mean of the coating thickness on the test specimen, with an error margin of 5 µm or less (depending on the accuracy of the micrometer).

6.2 Method No. 3B - Determination of the thickness of coatings using a multi-turn indicator

6.2.1 General

This method makes it possible to measure the thickness of the dried coating by means of control within the measurement accuracy of 2 µm.

6.2.2 Measuring instruments

A multi-turn indicator or any other indicator designed for lines: measurements, having a measuring rod for mechanical contact with the surface of the product, equipped with a mechanical, optical or electronic reading device, with accurate measurements in the range of 2 microns and mounted on a rigid base ().

6.2.3 Test procedure

6.2.3.1 Select the points at which measurements are to be taken. The measuring points must be free from surface defects and located at least 20 mm apart from the edge of the paintwork, at a distance of ≈ 50 mm from each other.

When working with large painted surfaces, the number of measurement points and their location on the surface must be such as to obtain reliable data characterizing the coating thickness over the entire painted area.

A circle with a diameter of ≈ 10 mm is drawn around each measurement point with light pressure and a serial number is placed next to it.

6.2.3.2 Position the colored specimen so that neither the pressure of the dipstick nor the removal of the coating will change its position.

Install the indicator vertically on the sample so that the measuring rod is above the center of the first measurement point. Carefully lower the measuring rod until it makes firm contact with the coating. Record the indicator readings and the number of the measurement point in the test report. The measuring rod is lowered onto the coating several times, recording the readings. Remove the measuring rod and remove the paint coating within the circle at each measurement point with an appropriate solvent or mechanically. To do this, the test area is covered with a round piece of thick filter paper and a few drops of the appropriate solvent are applied to it.

Carefully lower the measuring rod to the same place until it is in close contact with the surface to be painted and record the readings. Take measurements several times.

6.2.3.3 Repeat the procedure at each measurement point.

6.2.4 Handling results

6.2.4.1 Calculate the thickness of the coating at each measurement point by subtracting the reading obtained after the removal of the coating from the reading obtained before it.

6.2.4.2 Calculate the arithmetic mean of the coating thickness on the test specimen to the nearest 2 µm.

7 Method No. 6 - Magnetic method ( )

7.1 General

This method belongs to the category of non-destructive and is used to determine the thickness of non-magnetic dried coatings on magnetic metal substrates.

7.2 Measurement methods

7.2.1 Method No. 6A - Magnetic induction method

The instruments used in this method measure the resistance of the magnetic flux passing through the coating and the base.

7.2.2 Method No. 6B - Permanent magnet pull-off method

The instruments used in this method measure the magnetic attraction between the permanent magnet and the base, with the coating affecting the magnitude of the magnetic attraction.

7.3 Instrument calibration

7.3.1 General

Before operation, each device must be calibrated in accordance with the instructions for use using calibration standards. For instruments that cannot be calibrated, determine the deviation from the nominal value by comparison with calibration standards and take this deviation into account for all measurements.

Calibration should be carried out at short intervals during the operation of the instrument.

7.3.2 Calibration standards

Calibration standards of known and uniform thickness are used either in the form of foil or plates, or as colored standards with thickness values ​​indicated on them, verified in accordance with current state standards.

The surface and magnetic characteristics of the base metal of the colored calibration standards shall be similar to those of the test specimen.

The base thickness of the test specimen and the calibration standard shall be the same unless the critical value specified in 7.4.2 is exceeded.

7.4 Test procedure

7.4.1 General

When operating the devices, the manufacturer's instructions must be followed. Check instrument calibration () on a test stand before each use and at short intervals (at least once an hour) to ensure measurement accuracy.

7.4.2 Thickness of the metal base

For each device there is a critical base thickness value, above which an increase in thickness no longer affects the measurement results.

Check whether the thickness of the base of the sample exceeds the critical value. If the result is negative, increase the thickness by joining with the same metal or obtain confirmation of the calibration on a calibration standard of the same thickness and with the same magnetic properties as the test sample,

7.4.3 Number of measurements

Considering the usual spread of readings, it is necessary to take several measurements at each control area (for example, three measurements) in order to obtain the local thickness as the arithmetic mean of the results of a number of measurements. The number and distribution of control plots may be subject to discussion by stakeholders.

8 Method No. 7 - Eddy current method ( )

8.1 General

This non-destructive method can be used to determine the thickness of non-conductive dried coatings on non-magnetic metal substrates.

8.2 Method of measurement

Eddy current devices operate on the principle of generating a high-frequency electromagnetic field in the sensor system of the device, causing eddy currents in the conductor on which the sensor is located, and the amplitude and phase of these currents are a function of the thickness of the non-conductive coating located between the conductor and the sensor.

8.3 Instrument calibration

8.3.1 General

Before operation, each device must be calibrated in accordance with the instructions for use using calibration standards.

During operation, the calibration of the instrument is checked at short intervals.

8.3.2 Calibration standards

Calibration standards of known and uniform thickness are used in the form of foil or as colored standards with thickness values ​​indicated on them, verified in accordance with current state standards.

Calibration foils are usually made from suitable plastic materials for this purpose. Since such standards are subjected to deformation during measurements, they should be changed frequently.

Painted standards consist of non-conductive coatings of known and uniform thickness with good adhesion to the substrate.

8.4 Test procedure

8.4.1 General

When operating the instruments, follow the manufacturer's instructions. Check the calibration of the instrument () on a test stand before each use and at short intervals (at least once an hour) to ensure measurement accuracy.

8.4.2 Number of measurements

Given the usual scatter of readings, it is necessary to take several measurements at each control area (for example, three measurements) in order to obtain the local thickness as the arithmetic mean of the results of a number of measurements. The number and distribution of control plots may be subject to discussion by stakeholders.

9 Test report

The test report must contain:

Information about the material from which the coating to be measured is made;

Additional information on;

Measurement result ( individual values thickness and its mean value with standard deviation; you can specify individual thickness values ​​along with minimum and maximum values);

Any deviation from the standard procedure;

The date of the measurements.

APPENDIX A
(reference)
Technical characteristics of devices for determining the thickness of paint coatings

Table A.1

Measurement method	Device type	Measurement range, mm	Error	Manufacturer
Micrometric method	Micrometer lever type MR	0 - 25	± 1 µm	JSC Caliber (Moscow)
	Micrometer lever type MR	0 - 25	± 2 µm	Same
Method for determining thickness using a multi-turn indicator	Multi-turn indicator
	MIG-1 type	0 - 1	1 µm	JSC Caliber (Moscow)
	MIG-2 type	0 - 2	2 µm
Eddy current method	Eddy current thickness gauge type VT-60N with microprocessor	0,005 - 1,0	3 + 0,2(1000/T and - 1)% ( T and - measured value of the coating thickness)	INPO Spectr (Moscow)
	Eddy current microprocessor coating thickness gauge type VT-51 NP	0,01 - 1,999	±(0.03 X+ 1.0) µm (X - measured value of coating thickness)	Same
Magnetic induction method	Magnetic microprocessor coating thickness gauge type MT-51 NP	0,004 - 1,999	±(0.03 X+ 1.0) µm(X - measured value of coating thickness)	INPO "Spectrum", (Moscow)
Magnetic induction method or eddy current method (depending on the sensor)	Device for measuring geometric parameters multifunctional "Constant K5" type IDZSH	0 - 5,0	No more than 2 %	JSC Constanta (St. Petersburg)

APPENDIX B
(recommended)
Non-magnetic coatings on magnetic base metals.
Coating thickness measurement. Magnetic method

B.1 Purpose and scope

This International Standard specifies requirements for the use of magnetic-type instruments for non-destructive measurement of the thickness of non-magnetic coatings (including vitreous and porcelain coatings). enamel coatings) on magnetic base metals.

The method is applicable only for measurements of flat samples.

B.2 Essence of the method

Coating thickness gauges of the magnetic type measure either the magnetic attraction between the permanent magnet and the coated base metal, or the resistance of the magnetic flux passing through the coating and the base metal.

B.3 Factors affecting measurement accuracy*

The following factors can affect the accuracy of the coating thickness measurement.

B.3.1 Coating thickness

The measurement accuracy varies with the thickness of the coating and depends on the design of the instrument. For thin coatings - the accuracy is constant and does not depend on the thickness. For thick coatings, the accuracy is approximately constant.

B.3.2 Magnetic properties of the base metal

Various magnetic properties of the base metal affect the accuracy of measuring the coating thickness with a magnetic tool. In practice, changes in the magnetic properties of low-carbon steels can be considered insignificant. In order to avoid the influence of several or single heat treatments and cold working, the instrument should be calibrated using a calibration standard with a base metal with the same properties as the test piece or, if possible, with the test piece before coating.

B.3.3 Base metal thickness

For each device there is a critical thickness of the base metal, above which an increase in thickness does not affect the accuracy of the measurement. Since the critical thickness depends on the sensor of the instrument and the nature of the base metal, its value is determined experimentally, unless it is specified by the manufacturer.

B.3.4 Edge effect

The method is sensitive to abrupt changes in the contour of the surface of the test sample. Measurements taken too close to an edge or on the inside of a recess will not be reliable unless the instrument is calibrated specifically for such measurements. The edge effect can extend up to 20 mm from the sample edge, depending on the instrument.

B.3.5 Curvature

Measurements are affected by the curvature of the surface of the test piece. The influence of surface curvature on measurement accuracy depends to a large extent on the model and type of instrument, but always increases with decreasing radius of curvature. Instruments with two-pole sensors can give different readings if their poles in the planes are parallel or perpendicular to the axis of the cylindrical surface. A similar effect can be obtained with a single-pole sensor with an unevenly worn tip.

Measurements made on bent test specimens require special instrument calibration.

B.3.6. Surface roughness

If repeated measurements made on a rough surface according to GOST 2789-73* within the standard sample differ significantly, the number of measurements should be increased to at least 5.

B.3.7 Machining direction of base metal

Measurements taken on instruments that have a two-pole probe or an unevenly worn single-pole probe can be affected by the direction machining magnetic base metal (for example, rolled metal), while the readings of the device change depending on the orientation of the sensor on the surface.

B.3.8 Remanent magnetism

The residual magnetism of the base metal affects the measurement accuracy of devices operating on the principle of a constant magnetic field. The effect of residual magnetism on measurement accuracy is much less when measurements are carried out with devices operating on the principle of an alternating magnetic field ().

B.3.9 Magnetic fields

Strong magnetic fields created by various types of electrical equipment can be a serious interference with the operation of magnetic devices using a constant magnetic field ().

*In this standard, measurements are made with the same accuracy as the instrument is calibrated.

B.3.10 Foreign particles

Instrument sensors shall provide physical contact with the surface under test. Since these devices are sensitive to foreign particles that interfere with direct contact between the sensor and the coating surface, the sensor tip should be checked for cleanliness.

B.3.11 Coating conductivity

Some magnetic devices operate at frequencies of 200 - 2000 Hz. At these frequencies, eddy currents occur in thick, highly conductive coatings, which can affect instrument readings.

B.3.12 Sensor pressure

The poles of the test probe must be applied at a constant but rather high pressure, but no deformation of the coating should occur, even if the coating material is soft. Soft coatings may be covered with foil, the foil thickness being subtracted from the test results. This solution is also necessary when measuring the thickness of phosphate coatings.

The readings of instruments operating on the principle of magnetic attraction can be affected by the direction of the magnet in relation to the earth's gravimetric field. Operation of the instrument's sensor in a horizontal or vertical orientation requires differential calibration. Without this calibration, work is not possible.

B.4 Instrument calibration

B.4.1 General

Before use, each instrument should be calibrated in accordance with the manufacturer's instructions, using appropriate calibration standards, or by comparing thickness measurements made on selected test specimens by the magnetic method specified in this International Standard against a specific coating. For instruments that cannot be calibrated, the deviation from the nominal value is determined by comparison with calibration standards and taken into account in all measurements.

The calibration of the instrument should be checked frequently during operation. Attention should be paid to the factors listed in , and to the methodology indicated in .

B.4.2 Calibration standards

As calibration standards of the same thickness, either spacers or foils or coated standards are used.

B.4.2.1 Calibration foil

Note — In this clause, the word "foil" is used to refer to a non-magnetic metallic or non-metallic foil or gasket.

Because of the difficulty in making sufficient contact, foil is generally not recommended for calibrating magnetic attraction instruments. It can be used to calibrate other types of instruments. Foil has advantages for calibration on curved surfaces and is more applicable in these cases than coated standards.

To prevent measurement errors, it is necessary to establish tight contact between the foil and the base metal. Elastic foil should be avoided whenever possible.

The calibration foil deforms and must therefore be changed frequently.

B.4.2.2 Coated standards

Coated standards consist of coatings of known and uniform thickness, firmly bonded to the base metal.

B.4.3 Control

B.4.3.1 The surface roughness and magnetic properties of the base metal of the calibration standards shall be similar to the roughness and properties of the specimen under test. To confirm their conformity, it is recommended to compare the readings obtained on the base metal of the test sample and the uncoated calibration standard.

B.4.3.2 In some cases, the calibration of the instrument is checked by turning the sensor up to 90° ( and ).

B.4.3.3 The thickness of the base metal of the test specimen and the calibration standard shall be the same, unless the critical thickness specified in is overestimated.

The thickness of the base metal of the calibration standard and the test specimen shall be sufficient to ensure that the instrument readings are independent of the thickness of the base metal.

B.4.3.4 If the curvature of the surface of the coating intended to be measured interferes with calibration on a flat surface, the curvature of the calibration standard or base metal on which the calibration foil is placed should be the same as the test specimen.

B.5 Measurement technique

B.5.1 General

Each instrument must be operated in accordance with the manufacturer's instructions. Particular attention should be paid to the factors listed in the section.

Instruments should be calibrated according to the test plan () each time before using the instrument and at frequent intervals during operation.

B.5.2 Base metal thickness

Check whether the thickness of the base metal does not exceed the critical thickness. If not greater, use the method specified in , or ensure that the calibration is carried out on a calibration standard having the same thickness and magnetic properties as the sample under test.

B.5.3 Edge effect

Measurements should not be taken close to the edge, hole, or inside the corner of the test piece, unless the instrument is specifically calibrated for such a measurement.

B.5.4 Curvature

B.5.5 Number of measurements

Taking into account the influence of various factors on instrument readings, it is necessary to make several measurements at each point of the measured surface in accordance with GOST 8.362-79. Local variation in coating thickness requires several measurements over a reference area; this applies especially to rough surfaces. Instruments operating on the principle of magnetic attraction are sensitive to vibrations, therefore higher measurement results should not be taken into account.

If the direction of machining has a strong influence on the readings, measurements on the test specimens should be taken with the probe in the same direction as during the calibration process. If this is not possible, four measurements should be made on the same measured surface area with the probe rotated up to 90°.

B.5.7 Remanent magnetism

In the presence of residual magnetism in the base metal, it is necessary, when using a two-pole device with a constant magnetic field, to carry out measurements in two directions that differ by 180 °.

days to receive reliable results, it is necessary to demagnetize the test sample.

B.5.8 Surface cleaning

Before measuring the thickness, the surface of the sample must be cleaned of dirt, grease, corrosion products without compromising the integrity of the coating. Measurements of coating thickness should be avoided in areas with visible defects that are difficult to remove: flux residues from soldering or welding, acid stains, scale, oxides.

B.5.9 Lead coatings

Lead coatings can stick to the magnet of a device that works on the principle of magnetic attraction. The use of a very thin oil film will improve the reproducibility of the measurements, and the remaining oil should be wiped off so that the surface is practically dry when measured. Do not use oil on surfaces other than lead.

B.5.10 Technical staff

The results obtained may depend on the skill of the operator. The pressure on the sensor or the rate of application of the balancing load on the magnet y different people different. Such effects can be reduced or minimized by using an instrument calibrated by the same operator who takes the measurement, or by using constant pressure transducers. In cases where constant pressure sensors are not used, the use of a measuring instrument is necessary.

B.5.11 Sensor location

The sensor of the instrument must be perpendicular to the test surface of the sample at the measurement point. For devices based on the measurement of the force of attraction, this is essential. For other instruments, it is desirable to slightly tilt the sensor and select the minimum angle of inclination. If on smooth surface the results obtained depend significantly on the angle of inclination, it is likely that the sensor is worn out and needs to be replaced.

In the event that a device operating on the principle of force attraction is used in a horizontal or vertical position, it must be calibrated for each position separately.

B.6 Measurement accuracy

The instrument shall be calibrated so that the coating thickness can be measured to within 10% of the actual thickness or to within ±1.5 µm, whichever is optimal (). This method can be very accurate.

APPENDIX B
(recommended)
Non-conductive coatings on metals with a non-magnetic base. Coating thickness measurement. Eddy current method (Foucault currents)

IN 1 Purpose and scope

This International Standard specifies a method for the use of eddy current instruments for the non-destructive measurement of the thickness of a non-conductive coating on non-magnetic substrate metals. This method is also used to measure the thickness of most oxide coatings produced by an anodizing process.

B.2 Nature of the method

Devices with Foucault currents work on the principle of generating a high-frequency electromagnetic field in the sensor system of the device, causing Foucault currents in the conductor on which the sensor is located; the amplitude and phase of these currents correspond to the thickness of the non-conductive coating located between the conductor and the sensor.

AT 3 Factors affecting measurement accuracy

B.3.1 Coating thickness

The method is characterized by measurements with different accuracy. For thin coatings, the accuracy (within absolute limits) is constant, does not depend on the coating thickness, and for a single measurement is about 0.5 µm. For coatings thicker than 25 µm, the measurement error is approximately a constant fraction of the coating thickness.

In case the coating thickness is 5 µm or less, it is recommended to take the average of several measurements. Sometimes it is not possible to achieve the accuracy specified in , for coatings less than 3 µm thick.

B.3.2 Electrical properties of base metal

Measurements by Foucault currents are affected by the electrical conductivity of the base metal, which depends on chemical composition and heat treatment.

The effect of conductivity on the measurement depends on the design and type of instrument.

B.3.3 Base metal thickness

For each instrument, there is a critical thickness of the base metal, above which an increase in the thickness of the base metal does not affect measurements. Since substrate thickness and electrical conductivity affect measurement accuracy, the critical thickness value should be determined experimentally if not specified by the manufacturer.

For a given measured frequency, the higher the electrical conductivity of the base metal, the smaller its critical thickness. For a given base metal, the higher the measured frequency, the smaller the critical thickness of the base metal.

B.3.4 edge effect

Instruments for measuring Foucault currents are sensitive to sudden changes in the configuration of the test sample. Therefore, measurements taken close to an edge or ledge require special instrument calibration.

B.3.5 Curvature

Measurements are affected by the curvature of the test piece. The effect of curvature depends on the design and type of instrument, always becomes more pronounced with decreasing radius of curvature on curved specimens, and requires special calibration of the instrument.

B.3.6 Surface roughness

Measurements are affected by the surface roughness of the base metal and coating. Rough surfaces can cause both systematic and random errors. Errors can be reduced by a large number measurements. Each measurement is carried out in different areas.

If the base metal is rough, it is necessary to set the zero value of the device at various points on the uncoated surface of the base metal. If no similar base metal is available, the coating on the test piece should be removed with a solution that does not damage the base metal.

B.3.7 Foreign particles

Foucault current measurement requires physical contact with the surface under test, so these instruments are sensitive to foreign material that prevents firm contact between the sensor and the coating surface. The probe tip should be checked for cleanliness.

B.3.8 Gauge pressure

The pressure at which the sensor is applied to the specimen under test affects the readings of the instrument and should therefore be kept constant. This can be achieved by using an appropriate clamping device.

B.3.9 Sensor position

The sensitivity of the instrument changes with the tilt of the probe, so the probe must always be mounted perpendicular to the surface under test at the measurement point. This can be achieved by using an appropriate clamping device.

B.3.10 Deformation of test specimens

Test samples with soft coatings or thin test specimens may be deformed by the probe. Measurements of such test specimens may not be possible and can only be performed using probes and clamping devices.

B.3.11 Sensor temperature

Since temperature fluctuations affect the performance of the sensor, it should be used under the same temperature conditions as when calibrating.

AT 4 Instrument calibration

B.4.1 General provisions

Prior to measurement, each instrument should be calibrated according to the manufacturer's instructions using appropriate calibration standards.

Attention should be paid to the factors listed in section , and the test procedure given in section .

B.4.2 Calibration standards

Calibration standards of known thickness are used in the form of foil or coated specimens.

B.4.2.1 Calibration foil

B.4.2.1.1 Calibration foils used to calibrate instruments are usually made from suitable plastic materials. Calibration foil is more efficient and suitable for calibrating curved surfaces than using coated standards.

B.4.2.1.2 To prevent measurement errors, contact must be maintained between the foil and the base metal. Stretch foils should not be used.

When calibrating against the foil, indentations are formed, so the foil should be changed if possible.

B.4.2.2 Coated standards

Coated standards consist of non-conductive coatings of known uniform thickness, firmly bonded to the base metal.

B.4.3 Control

B.4.3.1 The base of the calibration standards shall have the same electrical properties as the base metal of the test sample. To confirm the conformity of the calibration standards, it is recommended to compare the readings obtained on the base metal of the uncoated calibration standard and the test specimen.

B.4.3.2 In the event that the thickness of the base metal exceeds the critical thickness, it does not affect, as indicated in , the thickness measurement. In the event that the thickness of the base metal does not exceed the critical thickness, it should be, if possible, the same. If this is not possible, the calibration standard or test piece should be coated to an appropriate thickness with a metal having similar electrical properties so that the readings of the device do not depend on the thickness of the base metal. In this case, the coating on the calibration standard or test sample should be on one side, and there should be no gap between the base and covering metal.

B.4.3.3 In the event that the curvature of the coating being measured interferes with the calibration on a flat surface, the curvature of the coated standard or the base covered with calibration foil shall match the curvature of the specimen under test.

AT 5 Test procedure

B.5.1 General provisions

Each instrument is used in accordance with the manufacturer's instructions, paying attention to the factors listed in section .

The calibration of the instrument should be checked before testing and at short intervals (at least once an hour).

Precautions must be observed.

B.5.2 Base metal thickness

Check whether the thickness of the base metal exceeds the critical thickness. If not, apply the method specified in , or ensure that the calibration is carried out on a calibration standard with the same thickness and electrical properties as the sample under test.

B.5.3 edge effect

Measurements should not be taken close to an edge, hole, inner corner sample, etc., unless the instrument is specifically calibrated for such measurements.

B.5.4 Curvature

Measurements should not be made on curved surfaces of the test piece unless the instrument is specifically calibrated for such measurements.

B.5.5 Number of measurements

For a normal measurement of the device, it is necessary to take several readings at each point. Local fluctuations in coating thickness also require that several measurements be taken over a given area, this is especially true for rough surfaces.

B.5.6 Surface finish

Before taking measurements, it is necessary to remove any foreign matter from the surface, such as dirt, dust, corrosion products, without damaging the coating material.

AT 6 Measurement accuracy requirements

The instrument must be calibrated so that the coating thickness can be determined with a measurement error of ± 10% actual thickness. When measuring a coating thickness of less than 5 µm, it is recommended to select an average reading. Such accuracy cannot be obtained for coatings with a thickness of less than 3 µm.

Keywords: paints and varnishes, coatings, thickness determination, terms and definitions, measurement methods, micrometric method, multi-turn indicator, magnetic methods, Foucault currents, technical characteristics of devices

STATE STANDARD OF THE UNION OF THE SSR

TESTING NON-DESTRUCTIVE

ULTRASONIC THICKNESS GAUGE

GENERAL TECHNICAL REQUIREMENTS

GOST 28702-90

(ST SEV 6791-89)

USSR STATE COMMITTEE
ON PRODUCT QUALITY MANAGEMENT AND STANDARDS

Moscow

STATE STANDARD OF THE UNION OF THE SSR

Date of reference 01.01.92

This standard applies to ultrasonic thickness gauges designed to measure the thickness of products in the range from 0.1 to 1000 mm from materials with a propagation velocity of ultrasonic vibrations in them from 1500 to 12000 m/s, the principle of operation of which is based on the interaction with the product of radiated pulsed or continuous acoustic vibrations introduced into the product from piezoelectric transducers through intermediate contact sound-conducting media, from electromagnetic or magnetic-induction transducers, and establishes a mandatory classification (items 2, 3, 4 tables 1-3, paragraph 5 table 2; paragraphs 2.8.1 - 2.8.3, 2.8.9, 2.11, 2.13, 2.14) and recommended requirements for them.

1. CLASSIFICATION

1.1. According to their purpose, thickness gauges are divided into: general purpose; specialized. 1.2. According to the degree of automation, thickness gauges are divided into: manual control; automated control. 1.3. In terms of protection from environmental influences, thickness gauges are divided into the following versions: protected from ingress of solid bodies (dust) into the thickness gauge; protected from water ingress into the thickness gauge; explosion-proof; protected from the impact of an aggressive environment; protected from other external influences. 1.4. By resistance to mechanical stress, thickness gauges are divided into versions: vibration-resistant; vibration resistant; impact resistant; shockproof. The terms used in this standard and explanations for them are given in Appendix 1.

2. TECHNICAL REQUIREMENTS

2.1. Thickness gauges must be manufactured in accordance with the requirements of this standard, GOST 12997 for automated control thickness gauges and specifications for specific types of thickness gauges according to working drawings approved in the prescribed manner. 2.2. The main indicators for general purpose thickness gauges are given in Table. 13 .

Table 1

Manual control thickness gauges designed to measure the thickness of corroded, eroded products at values ​​of the surface roughness parameter Rz ³ 40 microns according to GOST 2789

	Name of indicator	Indicator value
Thickness gauges with a degree of protection not lower than IP53 according to GOST 14254 for operation at a temperature not lower than minus 10 °С	1. Range of measured thicknesses (for steel or aluminum), mm
	for thickness gauges with automatic adjustment to the propagation velocity of ultrasonic vibrations (UT) in product material, mm
	2. Limit of permissible value of the main error, mm:
	in the thickness range up to 300 mm
	in the thickness range over 300 mm	±(0.1 + 0.001X*)
	for thickness gauges with automatic adjustment (adjustment) to the ultrasonic propagation velocity in the product material	±(0.1 ± 0, lX)
	3. Time of continuous operation of the thickness gauge from an autonomous power source without its replacement or recharging, h, not less than:
	with reflective indicators
	for thickness gauges with automatic adjustment (adjustment) to the ultrasonic velocity in the product material, h
	4. Weight of the thickness gauge with an autonomous power source without piezoelectric transducers, kg, no more
	for thickness gauges with automatic adjustment (adjustment) to the ultrasonic propagation velocity in the product material, kg
Explosion-proof thickness gauges with a degree of protection not lower than IP54 according to GOST 14254 for operation at a temperature not lower than minus 10 °С	11. Range of measured thicknesses (for steel), mm
		± (0.1 + 0.001 X)
	3. Time of continuous operation of the thickness gauge from an autonomous power source without its replacement or recharging, h, not less than:
	with light emitting indicator
	with reflective indicator
	4. Weight of the thickness gauge with an autonomous power source, without piezoelectric transducers, kg, no more
	5. Mean time between failures, h, not less than
Explosion-proof thickness gauges with a degree of protection not lower than IP54 according to GOST 14254 for operation at temperatures up to minus 30 °C and below	1. Range of measured thicknesses (for steel), mm
	2. Limit of permissible value of the main error, mm
	for thickness gauges with automatic adjustment (adjustment) to the ultrasonic velocity in the product material, mm	± (0.1 ± 0.01 X)
	3. Time of continuous operation of the thickness gauge with a light-emitting indicator from one set of batteries or accumulators without their replacement or charging under normal conditions, h, not less
	4. Weight of the thickness gauge with an autonomous power source, kg, no more
Explosion-proof thickness gauges with a degree of protection not lower than IP54 according to GOST 14254 for operation at temperatures up to minus 30 ° C and below	5. Mean time between failures, h, not less than

* X - measured thickness, mm. ** Choose from a range as agreed with the consumer

table 2

Manual control thickness gauges designed to measure the thickness of products at values ​​of the surface roughness parameter Rz £ 40 microns according to GOST 2789

Name of indicator	Indicator value
5. Limit of permissible value of the main error, mm:
	± 0.003; ± 0.005; ±0.01; ± 0.02*
	±0.001X**; ± 0.01*
3. Power consumed from the network, VA, no more
4. Time of continuous operation from an autonomous power source without its replacement or recharging under normal conditions, h, not less
5. Thickness gauge weight, kg, no more
6. Time of one measurement on a standard sample, s, no more
7. The degree of protection against ingress of solids and water into the thickness gauge (according to GOST 14254), not worse
8. Mean time between failures, h, not less than

* Choose from a number in agreement with the consumer. ** X - measured thickness, mm. Note to table. 1-2. When expanding the functionality of thickness gauges, provided by the use of built-in microprocessor devices and (or) RAM devices of measurement results and (or) interface devices for connecting external devices for automatic recording of measurement results, it is allowed to normalize the values ​​of indicators of continuous operation time less than, and mass more than the set values.

Table 3

Automated control thickness gauges designed to measure the thickness of products in the process of their production or operation

Name of a subgroup of homogeneous products	Name of indicator	Indicator value
Rz£40 µm	1. Range of measured thicknesses (for steel), mm
	2. Limit of permissible value of the main error, mm:
	in the thickness range up to 10 mm	± 0.003; ± 0.005; 0.01*
	in the range of thicknesses over 10 mm	± 0.001 Х**; ± 0.01*
Thickness gauges for measuring the thickness of products with the value of the surface roughness parameter Rz> 40 µm	1. Range of measured thicknesses (for steel), mm
	1. Limit of permissible value of the main error, mm:
	in the thickness range up to 10 mm
	in the range of thicknesses over 10 mm	± (0.1 + 0.001 X)
	3. Thickness gauge weight, kg, no more
	4. Power consumed from the network, VA, no more
	5.Performance control:
	Number of measurements per second, not less than
Thickness gauges for measuring the thickness of products with the value of the surface roughness parameter Rz> 40 µm	Thickness gauge reconfiguration time when changing the object of control, s, no more
	6. The degree of protection against ingress of solids and water into the thickness gauge (according to GOST 14254), not worse
	7. Mean time between failures, h, not less than

* Choose from a number in agreement with the consumer, and according to paragraph 1 - with a breakdown into subranges. ** X - measured thickness, mm. 2.3. The upper and lower limits of the thickness measurement range should be selected from the following range: 0.1; 0.15; 0.2; 0.25; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 0.9; 1.0; 2.0; 5.0; 10.0; 15.0; 20.0; 30.0; 40.0; 50.0; 100.0; 200.0; 300.0; 400.0; 500.0; 1000.0 mm. Note. In thickness gauges that include two or more types of piezoelectric transducers, the thickness range limits must be set for each type of transducer. 2.4. Requirements for parameter limits controlled items limiting the scope of the thickness gauge 2.4.1. For general-purpose thickness gauges, the following limiting values ​​of the geometric parameters of products in the measurement zone should be established, limiting the scope of application when they are separately exposed: the maximum allowable value of the surface roughness parameter on the ultrasound input side; the maximum allowable value of the surface roughness parameter on the side opposite to the ultrasound input side; roughness parameter value Rz, set from the range: 2.5; 5; ten; twenty; 40; 80; 160; 320 mm; the maximum allowable radius of curvature of the surface of the hollow cylinder when ultrasound is introduced from the side of the convex surface, set from the range: 2; 3; 5; ten; fifteen; 20 mm; the maximum allowable non-parallelism of surfaces in the measurement section with a base length of 20 mm, set from the range: 0.3; 1.0; 3.0; 6.0 mm. 2.4.2. For specialized thickness gauges of specific types, standards or specifications for the measured product should be indicated, which unambiguously define the parameters that limit the scope of thickness gauges (thickness range, material, maximum allowable roughness or surface condition, minimum radius of curvature and maximum non-parallelism of surfaces). 2.4.3. For general purpose thickness gauges, the range of propagation velocities of ultrasonic vibrations in the material of the controlled products must be indicated. 2.4.4. For specialized thickness gauges intended for operation in conditions where the temperature of the measured products differs from the ambient temperature, the temperature range of the surface of the controlled product must be indicated. 2.5. For thickness gauges intended for measuring products with corroded or eroded surfaces, the conditional sensitivity to the detection of local thinning and the limit of the permissible value of the measurement error in the thinning zone should be normalized. Conditional sensitivity values ​​should be selected from the range: 0.5; 0.6; 0.8; 1.0; 1.2; 1.6; 2.0 mm. 2.6. Requirements for standardized metrological characteristics 2.6.1. The basic error of thickness gauges should be normalized on standard samples under normal test conditions. Normal test conditions must be established in the technical specifications for thickness gauges of specific types and correspond to the following: ambient temperature 20 ° C; ambient temperature deviation should not exceed: ± 2 or ± 5 ° С; relative humidity from 45 to 75%; atmospheric pressure from 86 to 106 kPa; the deviation of the supply voltage from the nominal value should not exceed ± 2%; when powered by networks alternating current general purpose maximum network frequency deviation from the nominal value ± 1%; the maximum allowable coefficient of higher harmonics - 5%; external electric and magnetic fields must be absent or be within limits that do not affect the operation of the thickness gauges. 2.6.2. For specialized thickness gauges, the values ​​of the complex of normalized metrological characteristics, including the limit of the permissible value of the main error, in the thickness range up to 500 mm must meet the requirements of GOST 8.051; over 500 mm are installed in agreement with the customer (consumer) of thickness gauges. 2.6.3. As characteristics of the sensitivity of the thickness gauge to the influencing factors, the limits of the permissible values ​​of the additional error from the influence of each of the factors are normalized. 2.6.4. The limit of the permissible value of the additional error caused by a change in the supply voltage from the minimum to the maximum value should not exceed half the limit of the permissible value of the main error of the thickness gauge. 2.6.5. The limit of the permissible value of the additional error from a change in the ambient temperature for every 10 ° C in the operating temperature range should not exceed half the limit of the permissible value of the main error. 2.6.6. The limit of the permissible value of the additional error due to changes in the surface temperature of the measured product and the piezoelectric transducer in the temperature range selected from the range: 10, 20, 40, 100 ° C, in any part of the operating temperature range, should not exceed half the limit of the permissible value of the main error of the thickness gauge. 2.6.7. If the values ​​of the additional errors specified in paragraphs. 2.6.5 , 2.6.6 , does not exceed 0.2 of the maximum permissible value of the basic error, it is allowed to normalize them for an extended or full operating temperature range. 2.6.8. If the values ​​of additional errors according to clause 2.6.4 and (or) additional errors for the full temperature range according to clause 2.6.7 do not exceed 0.2 of the limit of the main error, instead of the limits of the permissible value of the additional error, the limit of the permissible value of the error of the thickness gauge in the interval of the corresponding influencing quantity. 2.6.9. For general-purpose thickness gauges, the limits of permissible values ​​of the additional error and (or) errors in the range of values ​​or at the limit values ​​of the geometric parameters of products specified in clause 2.4.1 when they are separately exposed, as well as the function of the influence of each of the parameters on the lower and (or ) the upper value of the range of measured thicknesses. 2.6.10. Verification of the parameters specified in clause 2.6.9 should be carried out on standard samples. 2.6.11. If the thickness gauge includes several types of piezoelectric transducers, then the parameters and characteristics according to clause 2.6.9 must be given for each type of transducer. The set of normalized parameters, metrological characteristics and influence functions for converters of a particular type is established based on their purpose. 2.7. Requirements for the establishment time and duration of the operating mode 2.7.1. Thickness gauges must provide the main metrological characteristics after the time for establishing the operating mode. The time for establishing the operating mode of thickness gauges with an autonomous (accumulator or battery) or combined power source should be selected from the following range: 10, 15, 20 s; thickness gauges powered only from the mains - from the range: 1, 5, 10, 15 minutes from the moment the thickness gauge is turned on. 2.7.2. Thickness gauges powered by the electrical network must provide a minimum duration of continuous operation of at least 8 hours. 2.8. Design requirements 2.8.1. All types of thickness gauge connections must provide reliable electrical contact and strong mechanical fastening. 2.8.2. The materials used in the design of the thickness gauge must be non-flammable under the conditions of operation, transportation and storage of thickness gauges. 2.8.3. Places of connection of protective conductors, electrical clamps connected to accessible conductive parts, protection class, type of power supply must be clearly and firmly marked in accordance with GOST 25874. 2.8.4. Thickness gauges for manual control must be equipped with devices for mounting in the working position on the chest or arm of the operator in conditions of limited ability to move the operator. 2.8.5. Digital reading devices of thickness gauges must reproduce the results in decimal notation. The discreteness of the digital reading device is selected from the range: 0.001; 0.010; 0.100; 1,000 mm. 2.8.6. The scales of thickness gauges with pointer or light reading devices must be uniform. The value of the division of the scale in millimeters is chosen from the range: 0.001; 0.002; 0.005; 0.010; 0.020; 0.050; 0.100; 0.200; 0.500; 1,000; 2,000; 5,000. 2.8.7. At the request of the consumer, the thickness gauges must be able to interface through the interface with external information recording devices. 2.8.8. In thickness gauges with an autonomous power source, a power-on indicator, an indicator for the discharge of batteries (accumulators) and (or) an automatic power off device when the batteries (accumulators) of the autonomous power source are discharged should be provided. 2.8.9. Thickness gauges for automated control should be able to interface through the interface with devices for sorting controlled products according to the upper and lower maximum allowable thickness values. 2.9. Requirements for electrical supply and energy consumption 2.9.1. Power parameters of thickness gauges from electrical networks general purpose direct and alternating current must comply with GOST 21128. 2.9.2. As a characteristic of energy consumption for thickness gauges powered by electrical networks, the power consumption is normalized, and for thickness gauges with an autonomous power source, the time of continuous operation from the power source without replacing or recharging it. 2.10. Requirements for stability and strength to external influences 2.10.1. Requirements for the stability and strength of thickness gauges to the effects of climatic factors are set depending on the location during operation in accordance with GOST 15150, for thickness gauges of automated control - in accordance with GOST 12997. 2.10.2. Conditions of transportation and storage of thickness gauges in terms of the impact of climatic factors external environment set in accordance with GOST 15150, for automated control thickness gauges - in accordance with GOST 12997. 2.10.3. Thickness gauges, depending on the location during operation, must meet the requirements for stability and strength to mechanical stress in accordance with GOST 12997. 2.10.4. Thickness gauges in shipping containers must be resistant to mechanical and dynamic loads in accordance with GOST 12997. 2.10.5. The degree of protection of thickness gauges from the penetration of solid bodies, dust and water is set at the request of the consumer in accordance with the operating conditions in accordance with GOST 14254. 2.11. Security requirements 2.11.1. In the technical specifications for thickness gauges of specific types, electrical safety requirements must be established in accordance with GOST 12.2.007.0, ST SEV 3230-81. 2.11.2. For thickness gauges powered by general-purpose electrical networks, the values ​​of electrical insulation resistance and electrical strength of insulation between the circuits and the thickness gauge housing must be set in accordance with GOST 21657. 2.11.3. Explosion-proof thickness gauges must additionally meet the requirements of GOST 22782.0. 2.11.4. The average sound pressure level or vibrational velocity or intensity of ultrasound in the zone of contact of the piezoelectric transducer with the operator's body must comply with GOST 12.1.001 and must not exceed 110 dB or 1.6 10 -2 m/s, or 0.1 W/cm, respectively 2. 2.12. Reliability requirements 2.12.1. Reliability indicators of thickness gauges: 1) mean time between failures; 2) the average recovery time of a working state; 3) average service life. The values ​​of reliability, maintainability and durability indicators are set in accordance with GOST 27883. 2.12.2. The mean time between failures for specialized manual control thickness gauges designed to operate at a temperature not lower than minus 10 ° C should be at least 32,000 hours; for thickness gauges operating at temperatures up to minus 30 ° C and below - at least 25,000 hours; for automated control thickness gauges - not less than 10,000 hours. 2.13. The level of radio interference generated by the thickness gauge must not exceed the standards provided for in the All-Union Standards for Permissible Industrial Radio Interference (Norms 8-72). 2.14. Resistance of thickness gauges to electromagnetic interference 2.14.1. Thickness gauges powered by general-purpose electrical networks must remain operational under the influence of harmonic and impulse noise introduced into the power supply network. The interference parameters must correspond to those given in Fig. 1 and in table. four .

Table 4

2.14.2. Thickness gauges must remain operational when exposed to external harmonic interference of the magnetic field. The interference parameters must correspond to those given in Fig. 2. Note. The values ​​of voltage, current and field strength of electromagnetic interference are expressed, respectively, in decibels relative to 1 μV, 1 μA, 1 μV / m - for the electric field; 1 μA/m - for a magnetic field.

Harmonic interference voltage limits in the frequency band from 10 kHz to 30 MHz

1 - on the AC supply terminals; 2 - on DC power supply terminals

Limit values ​​of the magnetic field strength of harmonic interference in the frequency band from 30 Hz to 50 kHz

2.14.3. Thickness gauges must remain operational when exposed to harmonic interference from an external electric field with an effective field strength of 120 dB in the frequency band specified in the technical specifications for specific types of thickness gauges. 2.14.4. Additional requirements for noise immunity can be established in the technical specifications for thickness gauges of a particular type. At the request of the consumer, it is allowed to test thickness gauges with alternating voltage with a frequency of 100 Hz to 30 MHz of a sinusoidal characteristic. 2.15. The following data should be indicated in the operational documentation of thickness gauges: types of recommended contact media, temperature and other conditions for their use; information about the connection points of external devices for the removal or input of electrical signals, indicating the parameters of the input (output) signals and the permissible load; types of batteries used and their quantity. 2.16. Requirements for piezoelectric transducers The main parameters of the piezoelectric transducers included in the thickness gauge set are set in accordance with GOST 26266 in the technical specifications and operational documentation for transducers or thickness gauges. 2.17. The symbol of the ultrasonic thickness gauge should consist of the letters UT, model number, alphanumeric designation of the design (if necessary). Example symbol ultrasonic thickness gauge model number 93:

2.18. The nomenclature of the main quality indicators required in the development of technical specifications and specifications for ultrasonic thickness gauges is given in Appendix 2.

ATTACHMENT 1
Reference

EXPLANATION OF TERMS USED IN THIS STANDARD

	Explanation
General Purpose Thickness Gauge	Thickness gauge, in standards or specifications, on which a specific object of measurement is not installed
Specialized thickness gauge	Thickness gauge in standards or specifications on which a specific measurement object is installed
Manual thickness gauge	Thickness gauge designed to measure the thickness of products during step-by-step or continuous scanning of their surface with a transducer with the participation of an operator
Automated control thickness gauge	Thickness gauge designed to measure the thickness of products during step-by-step or continuous scanning of their surface with a transducer without operator intervention
Conditional sensitivity to the detection of local thinning	The smallest value of the diameter of a disk flat-bottomed reflector at a constant nominal value of the distance to it, the measurement error of the distance to which does not exceed the specified value
Thickness gauge error on roughness thickness standard samples when measured from a rough surface Thickness gauge error on roughness thickness standard samples when measured from a smooth surface Thickness gauge error on non-parallel standard samples	Difference between the readings of the thickness gauge indicator device and the value of the sample thickness measured along the protrusions The difference between the readings of the thickness gauge indicator device and the value of the sample thickness measured along the depressions ultrasonic vibrations into the sample

APPENDIX 2
Mandatory

NOMENCLATURE OF MAIN QUALITY INDICATORS,
INSTALLED DURING THE DEVELOPMENT OF TERMS OF REFERENCE
AND TECHNICAL CONDITIONS FOR ULTRASONIC THICKNESS GAUGE

Name of indicator

Thickness gauges

general purpose

specialized

TK for R&D

TK for R&D

1. PURPOSE INDICATORS

1.1. Thickness range

1.2. Limit of the permissible value of the basic error

1.3. Limits of permissible values ​​of additional errors due to influencing quantities, and (or) errors in the range of influencing quantities

1.4. Parameters of controlled products that limit the scope

1.5. Conditional sensitivity to the detection of local thinning

1.6. Degree of protection against ingress of solids, dust and water into the thickness gauge

1.7. Control performance (for automated control thickness gauges)

1.8. Time of one measurement (for thickness gauges of manual control)

2. STABILITY AND STRENGTH TO EXTERNAL INFLUENCES DURING OPERATION AND TRANSPORTATION

3. POWER SUPPLY AND CONSUMPTION CHARACTERISTICS

3.1. Power consumption

3.2. Time of continuous operation from an autonomous power source without its replacement or recharging

4. INDICATORS OF RELIABILITY

4.1. MTBF

4.2. Mean recovery time

4.3. Average term services

5. INDICATORS OF MATERIAL CONSUMPTION

5.1. Weight

5.2. dimensions

Note. Sign<+» означает применяемость; «-» - неприменяемость; « ± » - ограниченную применяемость для толщиномеров конкретного типа.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of Electrical Industry and Instrumentation of the USSR 2. DEVELOPERSV. T. Bobrov(topic leader), Ph.D. tech. sciences; V. P. Tsetens, cand. tech. sciences; V. A. Kalinin, cand. tech. Sciences ; L. L. Stukelman 3. APPROVED AND INTRODUCED BY Decree of the USSR State Committee for Product Quality Management and Standards dated October 29, 1990 No. 2710 4. Inspection period 1995, inspection frequency - 5 years5. The standard fully complies with ST SEV 6791-89 6. Instead of GOST 4.177-85 (in terms of acoustic thickness gauges) 7. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

	Item number
GOST 8.051-8.1
GOST 12.1.001-89
GOST 12.2.007.0-75
GOST 2789-73
GOST 12997-84	2.1 , 2.10.1- 2.10.4
GOST 14254-80
GOST 15150-69	2.10.1 , 2.10.2
GOST 21128-83
GOST 21657-83
GOST 22782.0-81
GOST 25874-83
GOST 26266-90
GOST 27883-88
ST SEV 3230-81
Norms 8-72