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Salary depending on the experience of the applicant

Non-destructive testing becomes important when the development of the coating has already been completed and it is possible to proceed to its industrial application. Before a coated product enters service, it is checked for strength, cracks, discontinuities, pores or other defects that could cause failure. The more complex the coated object is, the more likely it is to have defects. Table 1 presents and describes below the existing non-destructive methods for determining the quality of coatings.

Table 1. Non-destructive methods quality control of coatings before their operation.

#	Control method	Purpose and suitability of the test
1	visual observation	Identification of surface defects of the coating by visual inspection
2	Capillary control (color and luminescent)	Detection of surface cracks, pores and similar coating defects
3	Radiographic control	Identification of internal coating defects
4	Electromagnetic control	Detection of pores and cracks, the method is not suitable for detecting defects in corners and edges
5	Ultrasonic control	Detection of surface and internal defects, the method is not suitable for thin layers and for detecting defects in corners and edges

VISUAL INSPECTION

The simplest quality assessment is an external inspection of a coated product. Such control is relatively simple, it becomes especially effective when good lighting, when using a magnifying glass. As a rule, external inspection should be carried out by qualified personnel and in combination with other methods.

SPRAYING WITH PAINT

Cracks and depressions on the surface of the coating are detected by the absorption of paint. The surface to be tested is sprayed with paint. Then it is carefully wiped and an indicator is sprayed on it. After a minute, the paint emerges from cracks and other small defects and colors the indicator, thus revealing the contour of the crack.

FLUORESCENT CONTROL

This method is similar to the paint soak method. The test specimen is immersed in a solution containing fluorescent paint, which is applied to all cracks. After cleaning the surface, the sample is covered with a new solution. If the coating has any defects, the fluorescent paint in that area will be visible under UV light.

Both methods based on absorption are used only to detect surface defects. Internal defects are not detected. Defects lying on the surface itself are difficult to detect, since when wiping the surface before applying the indicator, the paint is removed from them.

RADIOGRAPHIC CONTROL

Inspection by penetrating radiation is used to detect pores, cracks and voids within the coating. X-rays and gamma rays pass through the material being tested and onto photographic film. The intensity of x-ray and gamma radiation changes as they pass through the material. Any pores, cracks, or changes in thickness will be registered on the film, and with the appropriate interpretation of the film, the position of all internal defects can be established.

Radiographic control is relatively expensive and slow. The operator must be protected from exposure. It is difficult to analyze products of complex shape. Defects are defined when their dimensions are more than 2% of the total thickness of the coating. Therefore, radiographic technique is not suitable for detecting small defects in large structures of complex shape, it gives good results on less complex products.

EDGE CURRENT CONTROL

Surface and internal defects can be determined using eddy currents induced in the product by introducing it into the electromagnetic field of the inductor. When moving the part in the inductor, or the inductor relative to the part, the induced eddy currents interact with the inductor and change its impedance. The induced current in the sample depends on the presence of conduction defects in the sample, as well as its hardness and size.

By applying appropriate inductances and frequencies, or a combination of both, defects can be detected. Eddy current control is impractical if the configuration of the product is complex. This type of inspection is unsuitable for detecting defects on edges and corners; in some cases from uneven surface the same signals can be received as from a defect.

ULTRASONIC CONTROL

In ultrasonic testing, ultrasound is passed through a material and changes in the sound field caused by defects in the material are measured. The energy reflected from defects in the sample is perceived by the transducer, which converts it into an electrical signal and feeds it to the oscilloscope.

Depending on the size and shape of the sample, longitudinal, transverse or surface waves are used for ultrasonic testing. Longitudinal waves propagate in the material under test in a straight line until they meet a boundary or discontinuity. The first boundary the incoming wave encounters is the boundary between the transducer and the product. Part of the energy is reflected from the boundary, and the primary pulse appears on the oscilloscope screen. The rest of the energy passes through the material until it encounters a defect or opposite surface, the position of the defect is determined by measuring the distance between the signal from the defect and from the front and back surfaces.

The discontinuities can be arranged so that they can be identified by directing the radiation perpendicular to the surface. In this case, the sound beam is introduced at an angle to the surface of the material to create shear waves. If the entry angle is sufficiently increased, then surface waves are formed. These waves travel along the contour of the sample and can detect defects near its surface.

There are two main types of installations for ultrasonic testing. The resonant test uses radiation with a variable frequency. When the natural frequency corresponding to the thickness of the material is reached, the oscillation amplitude increases sharply, which is reflected on the oscilloscope screen. The resonance method is mainly used to measure thickness.

In the pulse echo method, pulses of constant frequency with a duration of fractions of a second are introduced into the material. The wave passes through the material and the energy reflected from the defect or rear surface, falls on the converter. The transducer then sends another pulse and receives the reflected one.

The transmission method is also used to detect defects in the coating and to determine the adhesion strength between the coating and the substrate. In some coating systems, the measurement of reflected energy does not adequately identify the defect. This is due to the fact that the interface between the coating and the substrate is characterized by such a high reflection coefficient that the presence of defects hardly changes the total reflection coefficient.

The use of ultrasonic testing is limited. This can be seen from the following examples. If the material has a rough surface, the sound waves are scattered so strongly that the test becomes meaningless. To test objects of complex shape, transducers are needed that follow the contour of the object; surface irregularities cause spikes to appear on the oscilloscope screen, making it difficult to identify defects. Grain boundaries in metal act similarly to defects and scatter sound waves. Defects located at an angle to the beam are difficult to detect, since reflection occurs mainly not towards the transducer, but at an angle to it. It is often difficult to distinguish between discontinuities located close to one another. In addition, only those defects are detected, the dimensions of which are comparable with the sound wavelength.

Conclusion

Screening tests are undertaken during the initial stage of coating development. Since the number of different samples is very large during the search for the optimal mode, a combination of test methods is used to weed out unsatisfactory samples. This selection program usually consists of several types of oxidation tests, metallographic examination, flame tests and tensile tests. Coatings that have successfully passed the selection tests are tested under conditions similar to operational ones.

Once a particular coating system has been found to have withstood field testing, it can be applied to protect the actual product. Technology needs to be developed non-destructive testing final product before putting it into operation. The non-destructive technique can be used to detect surface and internal holes, cracks and discontinuities, as well as poor adhesion of the coating and substrate.

Capillary inspection of welded joints is used to detect external (surface and through) and. This method of verification allows you to identify defects such as hot and, lack of penetration, pores, shells and some others.

With the help of capillary flaw detection, it is possible to determine the location and size of the defect, as well as its orientation along the metal surface. This method applies to both and . It is also used in welding plastics, glass, ceramics and other materials.

The essence of the capillary control method is the ability of special indicator liquids to penetrate into the cavities of weld defects. Filling defects, indicator liquids form indicator traces, which are recorded during visual inspection, or with the help of a transducer. The order of capillary control is determined by standards such as GOST 18442 and EN 1289.

Classification of capillary flaw detection methods

Methods of capillary testing are divided into basic and combined. The main ones imply only capillary control with penetrating substances. Combined are based on the combined use of two or more, one of which is capillary control.

Basic control methods

The main control methods are divided into:

1. Depending on the type of penetrating agent:

• testing with penetrating solutions
• testing with filter suspensions

1. Depending on the method of reading information:

• luminance (achromatic)
• color (chromatic)
• luminescent
• luminescent color.

Combined methods of capillary control

Combined methods are subdivided depending on the nature and method of exposure to the surface being checked. And they are:

1. Capillary-electrostatic
2. Capillary-electroinduction
3. Capillary magnetic
4. Capillary radiation absorption method
5. Capillary-radiation method of radiation.

Technology of capillary flaw detection

Before capillary testing, the surface to be tested must be cleaned and dried. After that, an indicator liquid - panetrant is applied to the surface. This liquid penetrates the surface defects of the seams and, after some time, an intermediate cleaning is carried out, during which excess indicator liquid is removed. Next, a developer is applied to the surface, which begins to draw out the indicator liquid from the welded defects. Thus, defect patterns appear on the controlled surface, visible to the naked eye, or with the help of special developers.

Stages of capillary control

The process of capillary control can be divided into the following stages:

1. Preparation and pre-cleaning
2. Intermediate cleaning
3. Manifestation process
4. Detection of welding defects
5. Drawing up a protocol in accordance with the results of the check
6. Final surface cleaning

Materials for capillary control

Scroll necessary materials for capillary flaw detection is given in the table:

indicator liquid	intermediate cleaner	Developer
Fluorescent liquids colored liquids Fluorescent colored liquids		dry developer
	Emulsifier on oil based	liquid developer water based
	Soluble Liquid Cleaner	Aqueous developer in suspension
	Water sensitive emulsifier
	Water or solvent	Liquid developer based on water or solvent for special applications

Preparation and preliminary cleaning of the surface to be checked

If necessary, contaminants such as scale, rust, oil stains, paint, etc. are removed from the controlled surface of the weld. These contaminants are removed using mechanical or chemical cleaning, or a combination of these methods.

Mechanical cleaning is recommended only in exceptional cases, if there is a loose film of oxides on the controlled surface or there are sharp drops between seam beads, deep undercuts. Limited use mechanical cleaning obtained due to the fact that when it is carried out, often surface defects are closed as a result of mashing, and they are not detected during inspection.

Chemical cleaning is carried out using various chemical cleaners that remove contaminants such as paint, oil stains, etc. from the surface being checked. Chemical residues can react with indicator liquids and affect the accuracy of the control. Therefore, chemicals after preliminary cleaning should be washed off the surface with water or other means.

After preliminary cleaning of the surface, it must be dried. Drying is necessary so that neither water, nor solvent, nor any other substances remain on the outer surface of the joint being checked.

Application of indicator liquid

The application of indicator liquids to the controlled surface can be carried out in the following ways:

1. capillary way. In this case, the filling of welded defects occurs spontaneously. The liquid is applied by wetting, dipping, streaming or spraying. compressed air or inert gas.
2. Vacuum way. With this method, a rarefied atmosphere is created in the defect cavities and the pressure in them becomes less than atmospheric, i.e. a kind of vacuum is obtained in the cavities, which sucks the indicator liquid into itself.
3. compression method. This method is the opposite of the vacuum method. Filling of defects occurs under the influence of pressure on the indicator liquid, exceeding Atmosphere pressure. Under high pressure, the liquid fills the defects, displacing air from them.
4. ultrasonic method. Defect cavities are filled in an ultrasonic field using ultrasonic capillary effect.
5. deformation method. Defect cavities are filled under the influence of elastic oscillations of a sound wave on the indicator liquid or under static loading, which increases the minimum size of defects.

For better penetration of the indicator liquid into the defect cavities, the surface temperature should be in the range of 10-50°C.

Intermediate surface cleaning

Intermediate surface cleaning agents should be applied in such a way that the indicator liquid is not removed from surface defects.

Water cleaning

Excess indicator liquid can be removed by spraying or wiping with a damp cloth. At the same time, mechanical impact on the controlled surface should be avoided. The water temperature should not exceed 50°C.

Solvent cleaning

First, excess fluid is removed with a clean, lint-free cloth. After that, the surface is cleaned with a cloth dampened with solvent.

Purification with emulsifiers

Water-sensitive emulsifiers or oil-based emulsifiers are used to remove indicator liquids. Before applying the emulsifier, wash off excess indicator liquid with water and immediately apply the emulsifier. After emulsification, it is necessary to wash the metal surface with water.

Combined cleaning with water and solvent

With this method of cleaning, first, excess indicator liquid is washed off the controlled surface with water, and then the surface is cleaned with a lint-free cloth moistened with a solvent.

Drying after intermediate cleaning

To dry the surface after intermediate cleaning, several methods can be used:

• wiping with a clean, dry, lint-free cloth
• evaporation at a temperature environment
• drying at elevated temperature
• air drying
• a combination of the above drying methods.

The drying process must be carried out in such a way that the indicator liquid does not dry out in the defect cavities. To do this, drying is carried out at a temperature not exceeding 50°C.

The process of manifestation of surface defects in the weld

The developer is applied to the controlled surface in an even thin layer. The development process should be started as soon as possible after the intermediate cleaning.

dry developer

Dry developer can only be used with fluorescent indicator liquids. Dry developer is applied by spraying or electrostatic spraying. Controlled areas should be covered uniformly, evenly. Local accumulations of developer are not allowed.

Liquid developer based on aqueous suspension

The developer is applied uniformly by dipping the controlled compound into it or by spraying with the help of an apparatus. When using the immersion method, for best results, the duration of the immersion should be as short as possible. After that, the controlled compound must be dried by evaporation or blowing in an oven.

Solvent based liquid developer

The developer is sprayed onto the surface to be inspected in such a way that the surface is uniformly wetted and a thin and uniform film is formed on it.

Liquid developer in the form of an aqueous solution

Uniform application of such a developer is achieved by immersing controlled surfaces into it, or by spraying with special devices. The immersion should be short, in which case the best test result is achieved. After that, the controlled surfaces are dried by evaporation or blowing in an oven.

The duration of the development process

The duration of the development process continues, as a rule, for 10-30 minutes. AT individual cases an increase in the duration of manifestation is allowed. The countdown of the development time begins: for dry developer immediately after its application, and for liquid developer - immediately after the surface has dried.

Identification of welding defects as a result of capillary flaw detection

If possible, inspection of the surface to be inspected begins immediately after the developer has been applied or after it has dried. But the final control occurs after the completion of the process of manifestation. Magnifying glasses or glasses with magnifying lenses are used as auxiliary devices for optical control.

When using fluorescent indicator liquids

Photochromic glasses are not allowed. It is necessary that the inspector's eyes adjust to the darkness in the test booth for at least 5 minutes.

Ultraviolet radiation must not enter the eyes of the inspector. All controlled surfaces must not fluoresce (reflect light). Also, objects that reflect light under the influence of ultraviolet rays should not fall into the field of view of the controller. General UV lighting may be used to allow the inspector to move freely around the test chamber.

When using colored indicator liquids

All controlled surfaces are inspected in daylight or artificial lighting. Illumination on the tested surface must be at least 500 lx. At the same time, there should be no glare on the surface due to the reflection of light.

Repeated capillary control

If there is a need for re-inspection, then the entire process of capillary flaw detection is repeated, starting with the pre-cleaning process. To do this, it is necessary, if possible, to provide more favorable conditions for control.

For repeated control, it is allowed to use only the same indicator liquids, of the same manufacturer, as during the first control. The use of other fluids, or the same fluids from different manufacturers, is not allowed. In this case, it is necessary to perform a thorough cleaning of the surface so that no traces of the previous check remain on it.

According to EN571-1, the main stages of capillary control are presented in the diagram:

Video on the topic: "Capillary flaw detection of welds"

TESTING NON-DESTRUCTIVE

Color method for testing joints, deposited and base metal

General Director of OAO VNIIPKhimnefteapparatura	V.A. Panov
Head of standardization department	V.N. Zarutsky
Head of Department No. 29	S.Ya. Luchin
Head of Laboratory No. 56	L.V. Ovcharenko
Development Manager, Senior Researcher	V.P. Novikov
Lead Engineer	L.P. Gorbatenko
Engineer-technologist II cat.	N.K. Lamina
Standardization engineer I cat.	BEHIND. Lukin
co-executor Head of the department of JSC "NIIKHIMMASH"	N.V. Khimchenko
AGREED Deputy General Director for research and production activities OJSC "NIIKHIMMASH"	V.V. crayfish

Foreword

1. DEVELOPED by JSC "Volgograd Research and Design Institute of Technology of Chemical and Petroleum Apparatus" (JSC "VNIIPT Chemical and Petroleum Apparatus")

2. APPROVED AND INTRODUCED technical committee No. 260 "Equipment for chemical and oil and gas processing" Approval Sheet of December 1999

3. AGREED by the letter of Gosgortekhnadzor of Russia No. 12-42/344 dated April 5, 2001.

4. REPLACE OST 26-5-88

1 area of ​​use. 2 3 General provisions. 2 4 Requirements for the area of ​​control by the color method .. 3 4.1 General requirements. 3 4.2 Requirements for the workplace of control by the color method .. 3 5 Defectoscopy materials.. 4 6 Preparing for color testing.. 5 7 Control method. 6 7.1 Application of indicator penetrant. 6 7.2 Removal of indicator penetrant. 6 7.3 Application and drying of the developer. 6 7.4 Inspection of the controlled surface. 6 8 Evaluation of surface quality and registration of control results. 6 9 Safety requirements. 7 Appendix A. Roughness standards of the controlled surface. eight Appendix B. Maintenance standards for color inspection .. 9 Appendix B. Illumination values ​​of the controlled surface. nine Appendix D. Control samples for checking the quality of flaw detection materials. nine Appendix D. List of reagents and materials used in the control by the color method .. 11 Appendix E. Preparation and rules for the use of flaw detection materials. 12 Appendix G. Storage and quality control of flaw detection materials. fourteen Appendix I. Consumption rates for flaw detection materials. fourteen Appendix K. Methods for assessing the quality of degreasing a controlled surface. fifteen Appendix K. Form of the control log by the color method .. 15 Annex M. Form of conclusion based on the results of control by the color method .. 15 Appendix H. Examples of abbreviated recording of color control .. 16 Appendix P. Passport for a control sample. sixteen

OST 26-5-99

INDUSTRY STANDARD

Introduction date 2000-04-01

1 AREA OF USE

This standard applies to the non-ferrous method of testing welded joints, deposited and base metal of all grades of steel, titanium, copper, aluminum and their alloys.

The standard is valid in the chemical, oil and gas engineering industry and can be used for any facilities controlled by the Gosgortekhnadzor of Russia.

The standard establishes requirements for the methodology for preparing and conducting color testing, controlled objects (vessels, apparatus, pipelines, metal structures, their elements, etc.), personnel and workplaces, flaw detection materials, evaluation and presentation of results, as well as safety requirements.

2 REGULATORY REFERENCES

GOST 12.0.004-90 SSBT Organization of labor safety training for employees

GOST 12.1.004-91 SSBT. Fire safety. General requirements

GOST 12.1.005-88 SSBT. General sanitary and hygienic requirements for air working area

PPB 01-93 Rules fire safety In Russian federation

Rules for attestation of non-destructive testing specialists approved by Gosgortekhnadzor of Russia

RD 09-250-98 Regulations on the procedure for safe repair work at chemical, petrochemical and oil refining hazardous production facilities, approved by the Gosgortekhnadzor of Russia

RD 26-11-01-85 Instructions for testing welded joints inaccessible for radiographic and ultrasonic testing

SN 245-71 Sanitary standards design of industrial enterprises

Standard instruction for carrying out gas hazardous work, approved by the USSR Gosgortekhnadzor on 20.02.85.

3 GENERAL

3.1 The color method of non-destructive testing (color flaw detection) refers to capillary methods and is designed to detect defects such as discontinuities that emerge on the surface.

3.2 The use of the color method, the scope of control, the defect class is established by the developer of the design documentation for the product and reflected in the technical requirements of the drawing.

3.3 The required sensitivity class of testing by the color method in accordance with GOST 18442 is ensured by the use of appropriate flaw detection materials when meeting the requirements of this standard.

3.4 The control of objects made of non-ferrous metals and alloys should be carried out before their mechanical processing.

3.5 Control by the color method should be carried out before the application of paint and varnish and other coatings or after their complete removal from the controlled surfaces.

3.6 When testing an object by two methods - ultrasonic and color, the control by the color method should be carried out before ultrasonic.

3.7 The surface to be controlled by the color method must be cleaned of metal splashes, soot, scale, slag, rust, various organic matter(oils, etc.) and other contaminants.

In the presence of metal splashes, soot, scale, slag, rust, etc. contamination, the surface is subject to mechanical cleaning.

Mechanical cleaning of the surface of carbon steels, low-alloy steels, and those similar in mechanical properties should be carried out with a grinding machine with an electrocorundum grinding wheel on a ceramic bond.

It is allowed to clean the surface with metal brushes, abrasive paper or in other ways in accordance with GOST 18442, ensuring compliance with the requirements of Appendix A.

Cleaning the surface from grease and other organic contaminants, as well as from water, is recommended to be carried out with heating this surface or objects, if the objects are small, for 40-60 minutes at a temperature of 100-120 ° C.

Note. Mechanical cleaning and heating of the controlled surface, as well as cleaning the object after testing, are not the responsibility of the flaw detectorist.

3.8 The roughness of the controlled surface must comply with the requirements of Appendix A of this standard and be specified in the regulatory and technical documentation for the product.

3.9 The surface to be controlled by the color method must be accepted by the QCD service based on the results of visual control.

3.10 In welded joints, the surface of the weld and adjacent sections of the base metal with a width not less than the thickness of the base metal, but not less than 25 mm on both sides of the weld with a metal thickness of up to 25 inclusive and 50 mm - with a metal thickness of more than 25 mm are subject to control by the color method. mm up to 50 mm.

3.11 Welded joints with a length of more than 900 mm should be divided into sections (zones) of control, the length or area of ​​which should be set so as to prevent the indicator penetrant from drying out before its re-application.

For circumferential welded joints and edges for welding, the length of the controlled section must be at the diameter of the product:

up to 900 mm - no more than 500 mm,

over 900 mm - no more than 700 mm.

The area of ​​the controlled surface should not exceed 0.6 m 2 .

3.12 When checking the inner surface of a cylindrical vessel, its axis should be inclined at an angle of 3 - 5° to the horizontal, ensuring the drain of waste liquids.

3.13 Control by the color method should be carried out at a temperature of 5 to 40 °C and a relative humidity of not more than 80%.

It is allowed to carry out inspection at temperatures below 5 °C using appropriate flaw detection materials.

3.14 Carrying out control by the color method during installation, repair or technical diagnostics of objects should be documented as gas hazardous work in accordance with RD 09-250.

3.15 Control by the color method should be carried out by persons who have undergone special theoretical and practical training and are certified in the prescribed manner in accordance with the "Rules for the certification of non-destructive testing specialists" approved by the Gosgortekhnadzor of Russia, and who have the appropriate certificates.

3.16 Service standards for color control are given in Appendix B.

3.17 This standard can be used by enterprises (organizations) in the development technological instructions and (or) other technological documentation for color control for specific objects.

4 REQUIREMENTS FOR THE AREA OF CONTROL BY THE COLOR METHOD

4.1 General requirements

4.1.1 The area of ​​control by the color method should be located in dry, heated, isolated rooms with natural and (or) artificial lighting and supply and exhaust ventilation in accordance with the requirements of CH-245, GOST 12.1.005 and 3.13, 4.1.4, 4.2.1 of this standard, away from high-temperature sources and mechanisms that cause sparking.

Supply air with a temperature below 5 °C should be heated.

4.1.2 When using flaw detection materials using organic solvents and other flammable and explosive substances, the control area should be located in two adjacent rooms.

In the first room, technological operations for the preparation and conduct of control, as well as inspection of controlled objects are performed.

In the second room there are heating devices and equipment on which work is performed that is not related to the use of flammable and explosive substances and which, according to safety regulations, cannot be installed in the first room.

It is allowed to carry out control by the color method at production (assembly) sites in full compliance with the control methodology and safety requirements.

4.1.3 In the area for the control of large objects, if the permissible concentration of vapors of the used flaw detection materials is exceeded, stationary suction panels, portable exhaust hoods or suspended extract panels mounted on a swivel single- or double-hinged suspension.

Portable and suspended suction devices must be connected to ventilation system flexible ducts.

4.1.4 Lighting in the control area by the color method should be combined (general and local).

It is allowed to use one general lighting in the event that the use of local lighting is impossible due to production conditions.

The luminaires used must be explosion-proof.

Illumination values ​​are given in Appendix B.

Using optical instruments and other means for examining the controlled surface, its illumination must comply with the requirements of the documents for the operation of these devices and (or) means.

4.1.5 The area of ​​control by the color method should be provided with dry clean compressed air at a pressure of 0.5 - 0.6 MPa.

Compressed air must enter the site through an oil-moisture separator.

4.1.6 The site must have a supply of cold and hot water with sewerage.

4.1.7 The floor and walls in the premises of the site must be covered with easily washable materials (metlakh tiles, etc.).

4.1.8 Cabinets for storing tools, devices, flaw detection and auxiliary materials, and documentation should be installed at the site.

4.1.9 The composition and arrangement of the equipment of the color control area must ensure the technological sequence of operations and comply with the requirements of Section 9.

4.2 Requirements for the workplace of the color method control

4.2.1 Workplace for control should be equipped with:

supply and exhaust ventilation and local exhaust with at least three air exchanges (an exhaust hood must be installed above the workplace);

a luminaire for local lighting, providing illumination in accordance with Appendix B;

a source of compressed air with an air reducer;

a heater (air, infrared or other type) that provides drying of the developer at a temperature below 5 °C.

4.2.2 A table (workbench) for checking small objects, as well as a table and a chair with a grate under the legs for the flaw detector operator, should be installed at the workplace.

4.2.3 The workplace must have the following devices, devices, tools, fixtures, flaw detection and auxiliary materials, and other accessories for testing:

paint sprayers with low air consumption and low productivity (for applying indicator penetrant or spray developer);

control samples and fixture (for checking the quality and sensitivity of flaw detection materials) in accordance with Appendix D;

loupes with 5x and 10x magnification (for general inspection of the controlled surface);

telescopic magnifiers (for examining controlled surfaces located inside the structure and remote from the eyes of the flaw detectorist, as well as surfaces in the form of sharp dihedral and polyhedral corners);

sets of standard and special probes (for measuring the depth of defects);

metal rulers (for determining the linear dimensions of defects and marking controlled areas);

chalk and (or) colored pencil (for marking controlled areas and marking defective places);

sets of painting hair and bristle brushes (for degreasing the controlled surface and applying indicator penetrant and developer);

a set of bristle brushes (for degreasing the controlled surface if necessary);

napkins and (or) rags made of cotton fabrics of the calico group (for wiping the controlled surface. It is not allowed to use napkins or rags made of woolen, silk, synthetic, and fleecy fabrics);

cleaning rags (to remove mechanical and other contaminants from the controlled surface, if necessary);

filter paper (for checking the quality of degreasing the controlled surface and filtering the prepared flaw detection materials);

rubber gloves (to protect the hands of the flaw detectorist from the materials used in the control);

cotton gown (for flaw detector);

cotton suit (for work inside the facility);

rubberized apron with a bib (for flaw detector);

rubber boots (for work inside the facility);

universal filtering respirator (for work inside the object);

a flashlight with a 3.6 W lamp (for work in installation conditions and during technical diagnostics of an object);

container tightly closed, unbreakable (for flaw detection materials for 5

one-time work, when carrying out control using brushes);

laboratory scales with a scale of up to 200 g (for weighing components of flaw detection materials);

a set of weights up to 200 g;

a set of flaw detection materials for testing (may be in an aerosol package or in a tightly closed unbreakable container, in an amount designed for one-shift work).

4.2.4 The list of reagents and materials used for color control is given in Appendix E.

5 DEFECTOSCOPIC MATERIALS

5.1 A set of flaw detection materials for testing by the color method consists of:

indicator penetrant (I);

penetrant cleaner (M);

penetrant developer (P).

5.2 The choice of a set of flaw detection materials should be determined depending on the required sensitivity of the control and the conditions for its use.

The sets of flaw detection materials are listed in Table 1, the recipe, preparation technology and rules for their use are given in Appendix E, storage rules and quality control - in Appendix G, consumption rates - in Appendix I.

It is allowed to use flaw detection materials and (or) their sets not provided for by this standard, provided that the necessary sensitivity of the control is ensured.

Table 1 - Sets of flaw detection materials

Industry designation set	Set assignment	Set assignment metrics
		Application conditions		Defectoscopy materials
		Temperature °C	application features	penetrant	cleaner	developer
			Flammable, toxic				at Ra? 6.3 µm
			Low toxicity, fireproof, applicable indoors requires thorough cleaning from the penetrant
	For rough welds		Flammable, toxic				at Ra? 6.3 µm
	For layer-by-layer inspection of welds		Flammable, toxic, no need to remove the developer before the next welding operation	Liquid K			at Ra? 6.3 µm
	To achieve high sensitivity		Flammable, toxic, applicable to objects that exclude contact with water	Liquid K	Oil-kerosene mixture		at Ra? 3.2 µm
(IFH-Color-4)			Environmentally and fireproof, non-corrosive, compatible with water	According to the manufacturer's specifications		Any according to Appendix E	at Ra = 12.5 µm
	For rough welds		Aerosol method of applying penetrant and developer	According to the manufacturer's specifications			at Ra? 6.3 µm
							at Ra? 3.2 µm
Notes: 1 The designation of the set in brackets is given by its developer. 2 Surface roughness (Ra) - according to GOST 2789. 3 Sets DN-1Ts - DN-6Ts should be prepared according to the recipe given in Appendix E. 4 Liquid K and paint M (manufactured by Lvov paint and varnish plant), sets: DN-8Ts (manufacturer IFKh UAN Kyiv), DN-9Ts and TsAN (manufacturer Nevinnomyssk petrochemical complex) - are supplied ready-made. 5 In parentheses are developers that can be used for these indicator penetrants.

6 PREPARATION FOR COLOR INSPECTION

6.1 In case of mechanized control, before starting work, it is necessary to check the operability of mechanization means and the quality of spraying of flaw detection materials.

6.2 Sets and sensitivity of flaw detection materials must comply with the requirements of Table 1.

Checking the sensitivity of flaw detection materials should be carried out according to Appendix G.

6.3 The surface to be inspected must comply with the requirements of 3.7 - 3.9.

6.4 The controlled surface must be degreased with the appropriate composition from a specific set of flaw detection materials.

It is allowed to use organic solvents (acetone, gasoline) for degreasing in order to achieve maximum sensitivity and (or) when conducting control at low temperatures.

Degreasing with kerosene is not allowed.

6.5 When conducting inspections in rooms without ventilation or inside the object, degreasing should be carried out aqueous solution powdered synthetic detergent (CMC) of any brand with a concentration of 5%.

6.6 Degreasing should be carried out with a stiff, bristled brush (brush) corresponding to the size and shape of the controlled area.

It is allowed to carry out degreasing with a napkin (rag) soaked in a degreasing composition, or by spraying a degreasing composition.

Degreasing of small objects should be carried out by immersing them in appropriate compounds.

6.7 The controlled surface after degreasing should be dried with a jet of clean, dry air at a temperature of 50 - 80 °C.

It is allowed to dry the surface with dry, clean cloth napkins, followed by exposure for 10 - 15 minutes.

Drying of small objects after degreasing is recommended to be carried out by heating them to a temperature of 100 - 120 ° C and holding at this temperature for 40 - 60 minutes.

6.8 When testing at low temperatures, the controlled surface should be degreased with gasoline, and then dried with alcohol using dry, clean cloths.

6.9 The surface, which was etched before the control, should be neutralized with an aqueous solution of soda ash with a concentration of 10 - 15%, washed clean water and dry with a stream of dry clean air with a temperature of at least 40 °C or dry, clean cloths, and then process in accordance with 6.4 - 6.7.

6.11 The controlled surface should be marked into sections (zones) in accordance with 3.11 and marked in accordance with the control card in the manner adopted at this enterprise.

6.12 The time interval between the end of the preparation of the object for control and the application of the indicator penetrant should not exceed 30 minutes. During this time, the possibility of condensation of atmospheric moisture on the controlled surface, as well as the ingress of various liquids and contaminants onto it, should be excluded.

7 CONTROL PROCEDURE

7.1 Application of indicator penetrant

7.1.1 The indicator penetrant should be applied to the surface prepared in accordance with Section 6 with a soft hair brush corresponding to the size and shape of the area (zone) being inspected, spraying (spray, aerosol method) or dipping (for small objects).

The penetrant should be applied to the surface in 5 - 6 layers, preventing the previous layer from drying out. The area of ​​the last layer should be slightly larger than the area of ​​the previously applied layers (so that the penetrant dried along the contour of the spot dissolves last layer without leaving traces, which, after application of the developer, form a pattern of false cracks).

7.1.2 When testing at low temperatures, the temperature of the indicator penetrant should not be lower than 15 °C.

7.2 Removal of indicator penetrant

7.2.1 The indicator penetrant should be removed from the monitored surface immediately after applying its last layer, with a dry, clean, lint-free cloth, and then with a clean cloth soaked in a cleaner (at low temperatures, in technical ethyl alcohol) until complete removal painted background, or in any other way according to GOST 18442.

At the roughness of the controlled surface Ra ? 12.5 µm background, formed by the remains of the penetrant, should not exceed the background established by the control sample according to Appendix G.

The oil-kerosene mixture should be applied with a bristle brush, immediately after applying the last layer of the penetrating liquid K, preventing it from drying out, while the area covered with the mixture should be slightly larger than the area covered with the penetrating liquid.

Removal of a penetrating liquid with an oil-kerosene mixture from a controlled surface should be done with a dry, clean rag.

7.2.2 The surface to be tested, after removing the indicator penetrant, should be dried with a dry, clean, lint-free cloth.

7.3 Applying and drying the developer

7.3.1 The developer should be a homogeneous mass without lumps and delaminations, for which it should be thoroughly mixed before use.

7.3.2 The developer should be applied to the controlled surface immediately after removal of the indicator penetrant, in one thin, even layer, ensuring the detection of defects, with a soft hair brush, corresponding to the size and shape of the controlled area (zone), spraying (spray, aerosol) or dipping (for small objects).

It is not allowed to apply the developer to the surface twice, as well as its sags and smudges on the surface.

When using the aerosol method of application, the valve of the spray head of the can with the developer should be blown with freon before use, to do this, turn the can upside down and briefly press the spray head. Then, turn the can with the spray head up and shake it for 2 - 3 minutes to mix the contents. Ensure good spray quality by pressing the spray head and pointing the spray away from the object.

With satisfactory atomization, without closing the valve of the spray head, the developer jet should be transferred to the controlled surface. The spray head of the can must be at a distance of 250 - 300 mm from the controlled surface.

It is not allowed to close the valve of the spray head when the jet is directed at the object in order to avoid large droplets of the developer on the controlled surface.

Spraying should be ended by directing the developer jet away from the object. At the end of spraying, blow the valve of the spray head again with freon.

In case of clogging of the spray head, it should be removed from the nest, washed in acetone and blown with compressed air (rubber bulb).

Paint M should be applied immediately after removing the oil-kerosene mixture, with a paint sprayer, to ensure the greatest sensitivity of the control. The time interval between the removal of the oil-kerosene mixture and the application of paint M should not exceed 5 minutes.

It is allowed to apply paint M with a hair brush when the use of a paint sprayer is not possible.

7.3.3 Drying of the developer can be carried out by natural evaporation or in a stream of clean, dry air with a temperature of 50 - 80 °C.

7.3.4 Drying of the developer at low temperatures can be carried out with the additional use of reflective electric heaters.

7.4 Inspection of the controlled surface

7.4.1 Inspection of the controlled surface should be carried out 20 - 30 minutes after the developer has dried. In cases of doubt when examining the controlled surface, a magnifier of 5 or 10 times magnification should be used.

7.4.2 Inspection of the controlled surface during layer-by-layer control should be carried out no later than 2 minutes after applying the developer on an organic basis.

7.4.3 Defects identified during the inspection should be noted in the manner adopted at this enterprise.

8 EVALUATION OF THE QUALITY OF THE SURFACE AND PRESENTATION OF THE RESULTS OF THE CONTROL

8.1 The assessment of the surface quality based on the results of the color control method should be carried out according to the shape and size of the indicator trace pattern in accordance with the requirements of the design documentation for the object or Table 2.

Table 2 - Standards for surface defects for welded joints and base metal

Type of defect	Defect class	Material thickness, mm	The maximum allowable linear size of the indicator trace of the defect, mm	The maximum allowable number of defects on a standard surface area
Cracks of all types and directions		Regardless	Not allowed
Separate pores and inclusions, revealed in the form of spots of a rounded or elongated shape		Regardless	Not allowed
			0.2S, but not more than 3
			No more than 3
			0.2S, but not more than 3
			or no more than 5
			No more than 3
			or no more than 5
			0.2S, but not more than 3
			or no more than 5
			No more than 3
			or no more than 5
			or no more than 9
Notes: 1 In anti-corrosion surfacing of 1 - 3 defectiveness classes, defects of all types are not allowed; for class 4 - single scattered pores and slag inclusions up to 1 mm in size are allowed, no more than 4 in a standard section of 100 × 100 mm and no more than 8 - in an area of ​​200 × 200 mm. 2 Standard section, with metal (alloy) thickness up to 30 mm - weld section 100 mm long or base metal area 100 × 100 mm, with metal thickness over 30 mm - weld section 300 mm long or base metal area 300 × 300 mm . 3 When different thickness welded elements, the determination of the dimensions of the standard section and the assessment of the quality of the surface should be carried out according to the element of the smallest thickness. 4 Indicator traces of defects are divided into two groups - extended and rounded, an extended indicator trace is characterized by a length to width ratio of more than 2, rounded - by a length to width ratio equal to or less than 2. 5 Defects should be defined as separate if the ratio of the distance between them to the maximum value of their indicator trace is more than 2, while the ratio is equal to or less than 2, the defect should be defined as one.

8.2 The results of the control should be recorded in the journal with the obligatory filling in of all its columns. The journal form (recommended) is given in Appendix L.

The journal must have continuous pagination, be laced and sealed with the signature of the head of the non-destructive testing service. Corrections must be confirmed by the signature of the head of the non-destructive testing service.

8.3 The conclusion on the results of the control should be drawn up on the basis of the log entry. The form of conclusion (recommended) is given in Appendix M.

It is allowed to supplement the journal and the conclusion with other information accepted at the enterprise.

8.5 Conventions type of defects and control technology - according to GOST 18442.

Recording examples are given in Appendix H.

9 SAFETY REQUIREMENTS

9.1 Persons certified in accordance with 3.15, who have undergone special instruction in accordance with GOST 12.0.004 on safety rules, electrical safety (up to 1000 V), fire safety in accordance with the relevant instructions in force at this enterprise, with a record of conducting briefing in a special magazine.

9.2 Flaw detectorists performing color inspection are subject to a preliminary (upon employment) and annual medical examination with a mandatory color vision test.

9.3 Work on the control by the color method should be carried out in overalls: a cotton gown (suit), a wadded jacket (at temperatures below 5 ° C), rubber gloves, a headgear.

When using rubber gloves, hands should first be coated with talcum powder or lubricated with petroleum jelly.

9.4 At the site of control by the color method, it is necessary to follow the fire safety rules in accordance with GOST 12.1.004 and PPB 01.

No smoking allowed, availability open fire and all kinds of sparks at a distance of 15 m from the place of control.

Posters should be posted at the work site: “Flammable”, “Do not enter with fire”.

9.6 The amount of organic liquids in the area of ​​control by the color method should be within the limits of the shift requirement, but not more than 2 liters.

9.7 Combustible substances should be stored in special metal cabinets equipped with exhaust ventilation or in hermetically sealed, unbreakable containers.

9.8 Used wiping material (napkins, rags) must be kept in a metal, tightly closed container and periodically disposed of in the manner established by the enterprise.

9.9 Preparation, storage and transportation of flaw detection materials should be carried out in unbreakable, hermetically sealed containers.

9.10 Maximum permissible concentrations of vapors of flaw detection materials in the air of the working area - according to GOST 12.1.005.

9.11 Inspection of the internal surface of objects should be carried out with a constant supply of fresh air inside the object, in order to avoid the accumulation of vapors of organic liquids.

9.12 Inspection by the color method inside the object should be carried out by two flaw detectorists, one of whom, being outside, ensures compliance with safety requirements, maintains auxiliary equipment, maintains communication and assists the flaw detector operator working inside.

The time of continuous work of the flaw detectorist inside the facility should not exceed one hour, after which the flaw detector operators should change each other.

9.13 To reduce the fatigue of flaw detectorists and improve the quality of control, it is advisable to take a break of 10 - 15 minutes after each hour of work.

9.14 Portable lamps must be explosion-proof with a power supply voltage of not more than 12 V.

9.15 When monitoring an object installed on a roller stand, a poster “Do not turn on, people are working” must be posted on the control panel of the stand.

9.16 When working with a set of flaw detection materials in an aerosol package, it is not allowed: spraying compositions near an open flame; smoking; heating a container with a composition above 50 ° C, placing it near a heat source and in direct sunlight, mechanical impact on the cylinder (impact, destruction, etc.), as well as ejection until the contents are completely used; contact with the eyes.

9.17 Hands, after carrying out the control by the color method, should be washed immediately with warm water and soap.

Do not use kerosene, gasoline or other solvents to wash your hands.

If the hands are dry after washing, it is necessary to apply skin softening creams.

It is not allowed to eat at the color control area.

9.18 The area of ​​control by the color method must be provided with fire extinguishing equipment in accordance with the current norms and rules of fire safety.

Annex A

(mandatory)

Roughness standards of the controlled surface

Object of control	Group of vessels, devices according to PB 10-115	Sensitivity class according to GOST 18442	Defect class	Surface roughness according to GOST 2789, microns, no more		Drop between weld beads, mm, no more
Welded joints of vessel and apparatus bodies (ring, longitudinal, welding of bottoms, nozzles and other elements), edges for welding
		Technological		Not processed
Technological surfacing of edges for welding
Anti-corrosion hardfacing
Areas of other elements of vessels and apparatuses where defects were found during visual inspection
Welded joints of pipelines R slave? 10 MPa
Welded joints of pipelines R slave< 10 МПа

Annex B

Maintenance standards for color inspection

Table B.1 - Scope of inspection for one flaw detectorist in one shift (480 min)

The actual value of the service rate (Nf), taking into account the location of the object and the conditions for monitoring, is determined by the formula:

Nf \u003d But / (Ksl? Kr? Ku? Kpz),

where No - service rate according to table B.1;

Kcl - complexity factor according to table B.2;

Кр - placement coefficient according to table B.3;

Ku - coefficient of conditions according to table B.4;

Kpz - the coefficient of the preparatory-final time, equal to 1.15.

The complexity of the control of 1 m of a weld or 1 m 2 of the surface is determined by the formula:

T \u003d (8? Ksl? Kr? Ku? Kpz) / But

Table B.2 - The coefficient of complexity of the control, Kcl

Table B.3 - Coefficient of placement of control objects, Kr

Table B.4 - Coefficient of control conditions, Ku

Annex B

(mandatory)

Illumination values ​​of the controlled surface

Sensitivity class according to GOST 18442	Minimum dimensions of the defect (cracks)		Illumination of the controlled surface, lx
	opening width, µm	length, mm	combined
	from 10 to 100
	from 100 to 500
Technological	Not standardized

Annex D

Control samples for checking the quality of flaw detection materials

D.1 Control sample with an artificial defect

The sample is made of corrosion-resistant steel and is a frame with two plates placed in it, pressed against each other by a screw (Fig. D.1). The contact surfaces of the plates must be lapped, their roughness (Ra) - no more than 0.32 microns, the roughness of other surfaces of the plates - no more than 6.3 microns according to GOST 2789.

An artificial defect (wedge-shaped crack) is created by a probe of the appropriate thickness, placed between the contact surfaces of the plates from one edge.

1 - screw; 2 - frame; 3 - plates; 4 - probe

a - control sample; b - plate

Figure D.1 - Control sample of two plates

D.2 Control samples of the enterprise

Samples can be made from any corrosion-resistant steels by the methods adopted at the manufacturer.

Specimens must have defects such as unbranched dead-end cracks with openings corresponding to the applied test sensitivity classes in accordance with GOST 18442. The width of the crack opening must be measured on a metallographic microscope.

The measurement accuracy of the crack opening width, depending on the control sensitivity class according to GOST 18442, should be for:

I class - up to 0.3 microns,

II and III classes - up to 1 micron.

Control samples must be certified and subjected to periodic inspection depending on the production conditions, but at least once a year.

The samples must be accompanied by a passport in the form given in Appendix II with a photograph of the picture of the detected defects and an indication of the set of flaw detection materials used in the control. The form of the passport is recommended, but the content is mandatory. The passport is issued by the non-destructive testing service of the enterprise.

If the control sample does not correspond to the passport data as a result of long-term operation, it should be replaced with a new one.

D.3 Technology for the manufacture of control samples

D.3.1 Sample No. 1

The test object is made of corrosion-resistant steel or its part with natural defects.

D.3.2 Sample No. 2

The sample is made of sheet steel grade 40X13 with a size of 100? 30? (3 - 4) mm.

A seam should be melted along the workpiece by argon-arc welding without the use of filler wire in the mode I = 100 A, U = 10 - 15 V.

Bend the workpiece on any fixture until cracks appear.

D3.3 Sample No. 3

The sample is made from sheet steel 1Kh12N2VMF or from any nitrided steel 30 × 70 × 3 mm in size.

The resulting workpiece is straightened and ground to a depth of 0.1 mm on one (working) side.

The workpiece is nitrided to a depth of 0.3 mm without subsequent hardening.

Grind the working side of the workpiece to a depth of 0.02 - 0.05 mm.

1 - adaptation; 2 - test sample; 3 - vice; 4 - punch; 5 - brace

Figure D.2 - Device for making a sample

The surface roughness Ra should be no more than 40 µm according to GOST 2789.

Place the workpiece in the fixture in accordance with Figure D.2, place the fixture with the workpiece in a vise and gently clamp until a characteristic crunch of the nitrided layer appears.

D.3.4 Background control

On the metal surface apply a layer of developer from the used set of flaw detection materials and dry it.

On the dried developer, apply once the indicator penetrant from this kit, diluted 10 times with the appropriate cleaner, and dry.

Annex D

(reference)

The list of reagents and materials used in the control of the color method

Gasoline B-70 for industrial and technical purposes

Laboratory filter paper

Cleaning rags (sorted) cotton

Auxiliary substance OP-7 (OP-10)

Drinking water

Distilled water

Liquid penetrating red K

Kaolin enriched for the cosmetic industry, grade 1

tartaric acid

Kerosene lighting

Paint M developing white

Dye fat-soluble dark red J (Sudan IV)

Dye fat-soluble dark red 5C

Dye "Rhodamin C"

Dye "Magenta sour"

Xylene coal

Transformer oil brand TK

Oil MK-8

Chalk chemically precipitated

Monoethanolamine

Sets of flaw detection materials according to Table 1, supplied ready-made

Sodium caustic grade A

Sodium nitrate chemically pure

Sodium phosphate trisubstituted

Sodium silicate soluble

Nefras С2-80/120, С3-80/120

Noriol brand A (B)

Soot white brand BS-30 (BS-50)

Synthetic detergent(CMC) - powder, any brand

Gum turpentine

soda ash

Ethyl alcohol rectified technical

Cotton fabrics of coarse calico group

Annex E

Preparation and rules for the use of flaw detection materials

E.1 Indicator penetrants

E.1.1 Penetrant I1:

dye fat-soluble dark red Zh (Sudan IV) - 10 g;

gum turpentine - 600 ml;

noriol brand A (B) - 10 g;

nefras C2-80/120 (C3-80/120) - 300 ml.

Dissolve dye G in a mixture of turpentine and noriol in a water bath at a temperature of 50 °C for 30 minutes. constantly stirring the composition. Add nefras to the resulting composition. Keep the composition to room temperature and filter.

E.1.2 Penetrant I2:

dye fat-soluble dark red J (Sudan IV) - 15 g;

gum turpentine - 200 ml;

lighting kerosene - 800 ml.

Completely dissolve dye G in turpentine, add kerosene to the resulting solution, place the container with the prepared composition in a boiling water bath and hold for 20 minutes. Cool down to a temperature of 30 - 40 ° C filter the composition.

E.1.3 Penetrant I3:

distilled water - 750 ml;

auxiliary substance OP-7 (OP-10) - 20 g;

dye "Rhodamin C" - 25 g;

sodium nitrate - 25 g;

rectified technical ethyl alcohol - 250 ml.

Completely dissolve the "Rhodamine C" dye in ethyl alcohol while constantly stirring the solution. Sodium nitrate and the excipient are completely dissolved in distilled water heated to a temperature of 50 - 60 °C. The resulting solutions are poured together while constantly stirring the composition. Keep the composition for 4 hours and filter.

When controlling according to sensitivity class III according to GOST 18442, it is allowed to replace "Rhodamin S" with "Rhodamin Zh" (40 g).

E.1.4 Penetrant I4:

distilled water - 1000 ml;

tartaric acid - 60 - 70 g;

dye "Magenta sour" - 5 - 10 g;

synthetic detergent (CMC) - 5 - 15 g.

Dye "Fuchsin sour", tartaric acid and synthetic detergent dissolve in distilled water heated to a temperature of 50 - 60 ° C, hold up to a temperature of 25 - 30 ° C and filter the composition.

E.1.5 Penetrant I5:

dye fat-soluble dark red Zh - 5 g;

dye fat-soluble dark red 5C - 5 g;

coal xylene - 30 ml;

nefras C2-80/120 (C3-80/120) - 470 ml;

gum turpentine 500 ml.

Dissolve dye Zh in turpentine, dye 5C - in a mixture of nefras and xylene, pour the resulting solutions together, mix and filter the composition.

E.1.6 Red penetrating liquid K.

Liquid K is a low-viscosity dark red liquid that does not have stratification, insoluble sediment and suspended particles.

With prolonged (over 7 hours) exposure to negative temperatures (up to -30 ° C and below), a precipitate may appear in liquid K due to a decrease in the dissolving power of its components. Before use, such a liquid should be kept at a positive temperature for at least a day, periodically stirring or shaking until the sediment is completely dissolved, and kept for at least an additional hour.

E.2 Indicator penetrant cleaners

E.2.1 Cleaner M1:

drinking water - 1000 ml;

auxiliary substance OP-7 (OP-10) - 10 g.

Auxiliary substance completely dissolve in water.

E.2.2 Cleaner M2: rectified technical ethyl alcohol - 1000 ml.

The cleaner should be used when low temperatures: from 8 to minus 40 °С.

E.2.3 Purifier M3: drinking water - 1000 ml; soda ash - 50 g.

Dissolve soda in water at a temperature of 40 - 50 ° C.

The cleaner should be used when monitoring in rooms with increased fire hazard and (or) small in volume, without ventilation, as well as inside objects.

B.2.4 Oil-kerosene mixture:

lighting kerosene - 300 ml;

transformer oil (MK-8 oil) - 700 ml.

Mix transformer oil (MK-8 oil) with kerosene.

It is allowed to deviate from the nominal oil volume by no more than 2% in the direction of decrease, and not more than 5% in the direction of increase.

The mixture should be thoroughly mixed before use.

E.3 Indicator penetrant developers

E.3.1 Developer P1:

distilled water - 600 ml;

enriched kaolin - 250 g;

rectified technical ethyl alcohol - 400 ml.

Add kaolin to a mixture of water and alcohol and mix until a homogeneous mass is obtained.

E.3.2 Developer P2:

enriched kaolin - 250 (350) g;

rectified technical ethyl alcohol - 1000 ml.

Mix kaolin with alcohol until smooth.

Notes:

1 When applying the developer with a paint sprayer, 250 g of kaolin should be added to the mixture, and when applied with a brush - 350 g.

2 Developer P2 can be used at the temperature of the controlled surface from 40 to -40 °C.

It is allowed to use chemically precipitated chalk or chalk-based tooth powder instead of kaolin in the composition of developers P1 and P2.

E.3.3 Developer P3:

drinking water - 1000 ml;

chemically precipitated chalk - 600 g

Mix chalk with water until smooth.

It is allowed to use chalk-based tooth powder instead of chalk.

E.3.4 Developer P4:

auxiliary substance OP-7 (OP-10) - 1 g;

distilled water - 530 ml;

white carbon black brand BS-30 (BS-50) - 100 g;

rectified technical ethyl alcohol - 360 ml.

Dissolve the auxiliary substance in water, pour alcohol into the solution and introduce soot. Mix the resulting composition thoroughly.

It is allowed to replace the auxiliary substance with a synthetic detergent of any brand.

E.3.5 Developer P5:

acetone - 570 ml;

nefras - 280 ml;

white soot brand BS-30 (BS-50) - 150 g.

Add soot to a solution of acetone with nefras and mix thoroughly.

E.3.6 White developer ink M.

Paint M is a homogeneous mixture of film former, pigment and solvents.

During storage, as well as during prolonged (over 7 hours) exposure to negative temperatures (up to -30 ° C and below), the paint pigment M precipitates, therefore, before use and when pouring into another container, it should be thoroughly mixed.

Warranty period of paint M - 12 months from the date of issue. After this period, paint M is subject to a sensitivity test in accordance with Appendix G.

E.4 Compositions for degreasing the controlled surface

E.4.1 Composition C1:

auxiliary substance OP-7 (OP-10) - 60 g;

drinking water - 1000 ml.

E.4.2 Composition C2:

auxiliary substance OP-7 (OP-10) - 50 g;

drinking water - 1000 ml;

monoethanolamine - 10 g.

E.4.3 Composition C3:

drinking water 1000 ml;

synthetic detergent (CMC) of any brand - 50 g.

E.4.4 Dissolve the components of each of the compositions C1 - C3 in water at a temperature of 70 - 80 °C.

Compositions C1 - C3 are applicable for degreasing any grades of metals and their alloys.

E.4.5 Composition C4:

auxiliary substance OP-7 (OP-10) - 0.5 - 1.0 g;

drinking water - 1000 ml;

sodium caustic grade A - 50 g;

trisubstituted sodium phosphate - 15 - 25 g;

sodium silicate soluble - 10 g;

soda ash - 15 - 25 g.

E.4.6 Composition C5:

drinking water - 1000 ml;

trisubstituted sodium phosphate 1 - 3 g;

sodium silicate soluble - 1 - 3 g;

soda ash - 3 - 7 g.

E.4.7 For each of the compositions C4 - C5:

dissolve soda ash in water at a temperature of 70 - 80 ° C, into the resulting solution alternately, in the specified sequence, introduce other components of a specific composition.

Compositions C4 - C5 should be used when testing objects made of aluminum, lead and their alloys.

After applying C4 and C5 compositions, the controlled surface should be washed with clean water and neutralized with a 0.5% aqueous solution of sodium nitrite.

Do not allow C4 and C5 formulations to come into contact with the skin.

E.4.8 It is allowed to replace the auxiliary substance in the compositions C1, C2 and C4 with a synthetic detergent of any brand.

E.5 Organic solvents

Gasoline B-70

Nefras С2-80/120, С3-80/120

The use of organic solvents shall be in accordance with the requirements of Section 9.

Annex G

Storage and quality control of flaw detection materials

G.1 Flaw detection materials should be stored in accordance with the requirements of applicable standards or specifications.

G.2 Sets of flaw detection materials should be stored in accordance with the requirements of the documents for the materials from which they are composed.

G.3 Indicator penetrants and developers should be stored in sealed containers. Indicator penetrants must be protected from light.

G.4 Compositions for degreasing and developers should be prepared and stored in unbreakable containers based on replacement needs.

G.5 The quality of flaw detection materials should be checked on two control samples. One sample (working) should be used continuously. The second sample is used as an arbitration sample if cracks are not detected on the working sample. If cracks are also not detected on the arbitration sample, then the flaw detection materials should be recognized as unsuitable. If cracks are detected on the reference sample, the working sample should be thoroughly cleaned or replaced.

Control sensitivity (K), when using a control sample in accordance with Figure D.1, should be calculated using the formula:

where L 1 - the length of the undetected zone, mm;

L is the length of the indicator trace, mm;

S - probe thickness, mm.

G.6 Control samples after their use should be washed in a cleaner or acetone with a bristle brush or brush (the sample according to Figure D.1 must first be disassembled) and dried with warm air or wiped with dry, clean cloths.

G.7 The results of testing the sensitivity of flaw detection materials should be recorded in a special log.

G.8 On aerosol cans and vessels with flaw detection materials there should be a label with data on their sensitivity and the date of the next check.

Appendix I

(reference)

Consumption rates of flaw detection materials

Table I.1

Approximate consumption of auxiliary materials and accessories per 10 m 2 of the controlled surface

Annex K

Methods for assessing the quality of degreasing a controlled surface

K.1 Method for evaluating the quality of solvent drop degreasing

K.1.1 Apply 2-3 drops of nefras to the degreased area of ​​the surface and hold for at least 15 s.

K.1.2 Place a sheet of filter paper on the area with applied drops and press it to the surface until the solvent is completely absorbed into the paper.

K.1.3 Apply 2 - 3 drops of nefras to another sheet of filter paper.

K.1.4 Hold both sheets until the solvent has completely evaporated.

K.1.5 Visually compare the appearance of both sheets of filter paper (illumination should be in accordance with the values ​​given in Appendix B).

K.1.6 The quality of the surface degreasing should be assessed by the presence or absence of spots on the first sheet of filter paper.

This method applicable for assessing the quality of degreasing a controlled surface with any degreasing compositions, including organic solvents.

K.2 Method for assessing the quality of degreasing by wetting.

K.2.1 Moisten the degreased area of ​​the surface with water and hold for 1 min.

K.2.2 The quality of degreasing should be assessed visually by the absence or presence of water droplets on the controlled surface (illumination should correspond to the values ​​given in Appendix B).

This method should be used when cleaning the surface with water or aqueous degreasers.

Annex L

The form of the control log with a color method

Date of control

Information about the object of control

Sensitivity class, set of flaw detection materials

Identified defects

conclusion on the results of control

Defectoscopist

name, drawing number

material grade

No. or designation of the welded joint according to fig.

No. of controlled area

at primary control

under control after the first correction

under control after re-correction

surname, ID number

Notes: 1 In the column "Identified defects", the dimensions of the indicator traces should be given. 2 If necessary, sketches of the location of indicator traces should be attached. 3 Designations of detected defects - according to Appendix H. 4 technical documentation according to the results of control should be stored in the archive of the enterprise in the prescribed manner.

Annex M

Conclusion form based on the results of control by the color method

	Company_____________________________ Name of the control object ____________ ________________________________________ Head No. __________________________________ Inv. No. _________________________________
CONCLUSION No. _____ from ___________________ according to the results of testing by the color method in accordance with OST 26-5-99, sensitivity class _____ set of flaw detection materials
Defectscopist _____________ /____________/, certificate number _______________ Head of NDT Service ______________ /______________/

Annex H

Examples of abbreviated color control records

H.1 Control record

P - (I8 M3 P7),

where P is the second class of control sensitivity;

I8 - indicator penetrant I8;

M3 - cleaner M3;

P7 - developer P7.

The industry designation of a set of flaw detection materials should be indicated in brackets:

P - (DN-7C).

H.2 Identification of defects

N - lack of penetration; P - it's time; Pd - undercut; T - crack; Ш - slag inclusion.

A - a single defect without a predominant orientation;

B - group defects without a predominant orientation;

C - ubiquitously distributed defects without a predominant orientation;

P - the location of the defect parallel to the axis of the object;

The location of the defect is perpendicular to the axis of the object.

Designations of permissible defects with an indication of their location should be circled.

Note - A through defect should be indicated with the sign "*".

H.3 Recording test results

2TA + -8 - 2 single cracks, located perpendicular to the axis of the weld, 8 mm long, unacceptable;

4PB-3 - 4 pores arranged in a group without a predominant orientation, with an average size of 3 mm, unacceptable;

20-1 - 1 group of pores 20 mm long, located without a predominant orientation, with an average pore size of 1 mm, acceptable.

Appendix P

The control sample was certified on ______ (date) ______ and recognized as suitable for determining the sensitivity of the control by the color method according to ___________ class GOST 18442 using a set of flaw detection materials

_________________________________________________________________________

A photograph of the control sample is attached.

Signature of the head of the non-destructive testing service of the enterprise

Capillary flaw detection

Capillary control

Capillary method of non-destructive testing

CapillI flaw detectorand I - a flaw detection method based on the penetration of certain liquid substances into the surface defects of the product under the action of capillary pressure, as a result of which the light and color contrast of the defective area increases relative to the undamaged one.

There are luminescent and color methods of capillary flaw detection.

In most cases, according to technical requirements it is necessary to detect defects so small that they can be noticed when visual control almost impossible to the naked eye. The use of optical measuring instruments, for example, a magnifying glass or a microscope, does not allow revealing surface defects due to insufficient image contrast of the defect against the background of metal and a small field of view at high magnifications. In such cases, the capillary control method is used.

During capillary testing, indicator liquids penetrate into the cavities of surface and through discontinuities in the material of the test objects, and the resulting indicator traces are recorded visually or using a transducer.

Control by capillary method is carried out in accordance with GOST 18442-80 “Non-destructive control. capillary methods. General requirements."

Capillary methods are divided into basic, using capillary phenomena, and combined, based on a combination of two or more physical non-destructive testing methods, one of which is capillary testing (capillary flaw detection).

Purpose of capillary inspection (capillary flaw detection)

Capillary flaw detection (capillary inspection) designed to detect invisible or poorly visible to the naked eye surface and through defects (cracks, pores, shells, lack of penetration, intergranular corrosion, fistulas, etc.) in test objects, determining their location, extent and orientation along the surface.

Capillary methods of non-destructive testing are based on capillary penetration of indicator liquids (penetrants) into the cavities of surface and through discontinuities in the material of the test object and registration of the indicator traces formed visually or using a transducer.

Application of the capillary method of non-destructive testing

The capillary method of control is used in the control of objects of any size and shape, made of ferrous and non-ferrous metals, alloy steels, cast iron, metal coatings, plastics, glass and ceramics in power engineering, aviation, rocketry, shipbuilding, chemical industry, metallurgy, construction nuclear reactors, in the automotive, electrical, mechanical engineering, foundry, stamping, instrumentation, medicine and other industries. For some materials and products, this method is the only one for determining the suitability of parts or installations for work.

Capillary flaw detection is also used for non-destructive testing of objects made of ferromagnetic materials, if they magnetic properties, shape, type and location of defects do not allow achieving the required sensitivity according to GOST 21105-87 by the magnetic particle method and the magnetic particle method of control is not allowed to be used according to the operating conditions of the object.

A necessary condition for the detection of defects such as discontinuity of the material by capillary methods is the presence of cavities free from contaminants and other substances that have access to the surface of objects and a propagation depth that is much greater than the width of their opening.

Capillary control is also used in leak detection and, together with other methods, in monitoring critical objects and objects during operation.

The advantages of capillary methods of flaw detection are: simplicity of control operations, simplicity of equipment, applicability to a wide range of materials, including non-magnetic metals.

The advantage of capillary flaw detection is that with its help it is possible not only to detect surface and through defects, but also to obtain valuable information about the nature of the defect and even some of the reasons for its occurrence (stress concentration, non-compliance with technology, etc.) ).

As indicator liquids, organic phosphors are used - substances that give a bright glow of their own under the action of ultraviolet rays, as well as various dyes. Surface defects are detected using means that allow extracting indicator substances from the cavity of defects and detecting their presence on the surface of the controlled product.

capillary (crack), coming to the surface of the object of control only on one side, is called a surface discontinuity, and connecting the opposite walls of the object of control, - through. If the surface and through discontinuities are defects, then it is allowed to use the terms "surface defect" and "through defect" instead. The image formed by the penetrant at the location of the discontinuity and similar to the shape of the section at the exit to the surface of the test object is called an indicator pattern, or indication.

With regard to a discontinuity such as a single crack, instead of the term "indication", the term "indicator trace" is allowed. Discontinuity depth - the size of the discontinuity in the direction inside the test object from its surface. The discontinuity length is the longitudinal dimension of the discontinuity on the surface of the object. Opening of a discontinuity - the transverse size of a discontinuity at its exit to the surface of the test object.

A necessary condition for reliable detection by the capillary method of defects that have access to the surface of an object is their relative uncontamination with foreign substances, as well as the propagation depth, which significantly exceeds the width of their opening (at least 10/1). A cleaner is used to clean the surface before applying the penetrant.

Capillary methods of flaw detection are divided into on the main, using capillary phenomena, and combined, based on a combination of two or more methods of non-destructive testing, different in physical essence, one of which is capillary.

Devices and equipment for capillary control:

• Kits for capillary flaw detection (cleaners, developers, penetrants)
• Spray guns
• Pneumohydroguns
• Sources of ultraviolet illumination (ultraviolet lamps, illuminators)
• Test panels (test panel)

Control samples for color flaw detection

Sensitivity of capillary flaw detection method

Capillary control sensitivity– ability to detect discontinuities given size with a given probability when using a specific method, control technology and penetrant system. According to GOST 18442-80 control sensitivity class is determined depending on minimum size identified defects with a transverse size of 0.1 - 500 microns.

Identification of defects with an opening width of more than 0.5 mm is not guaranteed by capillary inspection methods.

With sensitivity according to class 1, using capillary flaw detection, the blades of turbojet engines, sealing surfaces of valves and their seats, metal sealing gaskets of flanges, etc. (detected cracks and pores up to tenths of a micron) are controlled. According to the 2nd class, they check the bodies and anti-corrosion surfacing of reactors, the base metal and welded joints of pipelines, bearing parts (detectable cracks and pores up to several microns in size).

The sensitivity of flaw detection materials, the quality of intermediate cleaning and the control of the entire capillary process are determined on control samples (standards for color flaw detection of CD), i.e. on metal of a certain roughness with normalized artificial cracks (defects) applied to them.

The control sensitivity class is determined depending on the minimum size of detected defects. The comprehended sensitivity, if necessary, is determined on full-scale objects or artificial samples with natural or simulated defects, the dimensions of which are specified by metallographic or other methods of analysis.

According to GOST 18442-80, the control sensitivity class is determined depending on the size of the detected defects. As a parameter of the size of the defect, the transverse size of the defect on the surface of the test object is taken - the so-called width of the defect opening. Since the depth and length of the defect also have a significant effect on the possibility of its detection (in particular, the depth should be much greater than the opening), these parameters are considered stable. The lower threshold of sensitivity, i.e. minimum value disclosure of identified defects is limited by the fact that a very small amount of penetrant; lingering in the cavity of a small defect is insufficient to obtain a contrast indication for a given thickness of the developing agent layer. There is also an upper threshold of sensitivity, which is determined by the fact that from wide, but shallow defects, the penetrant is washed out when excess penetrant on the surface is eliminated.

There are 5 sensitivity classes (according to the lower threshold) depending on the size of the defects:

Sensitivity class	Defect opening width, µm
	Less than 1
	1 to 10
	10 to 100
	100 to 500
technological	Not standardized

Physical bases and technique of the capillary control method

Capillary method of non-destructive testing (GOST 18442-80) is based on capillary penetration into the defect of the indicator liquid and is designed to detect defects that have access to the surface of the test object. This method is suitable for detecting discontinuities with a transverse size of 0.1 - 500 microns, including through ones, on the surface of ferrous and non-ferrous metals, alloys, ceramics, glass, etc. Widely used to control the integrity of the weld.

A colored or coloring penetrant is applied to the surface of the test object. Due to the special qualities that are provided by the selection of certain physical properties penetrant: surface tension, viscosity, density, it, under the action of capillary forces, penetrates into the smallest defects that have access to the surface of the test object

The developer, applied to the surface of the test object some time after the penetrant is carefully removed from the surface, dissolves the dye located inside the defect and, due to diffusion, “pulls” the penetrant remaining in the defect onto the surface of the test object.

Existing defects are visible enough contrast. Indicator traces in the form of lines indicate cracks or scratches, individual dots indicate pores.

The process of detecting defects by the capillary method is divided into 5 stages (carrying out capillary control):

1. Preliminary cleaning of the surface (use a cleaner)

2. Application of the penetrant

3. Removal of excess penetrant

4. Applying the developer

5. Control

Preliminary cleaning of the surface. In order for the dye to penetrate into defects on the surface, it must first be cleaned with water or an organic cleaner. All contaminants (oils, rust, etc.) and any coatings (paintwork, plating) must be removed from the controlled area. After that, the surface is dried so that no water or cleaner remains inside the defect.

Application of penetrant. The penetrant, usually red in color, is applied to the surface by spraying, brushing or immersing in an OK bath for good impregnation and complete penetrant coverage. As a rule, at a temperature of 5-50 0 C, for a period of 5-30 minutes.

Removal of excess penetrant. Excess penetrant is removed by wiping with a tissue, rinsing with water. Or with the same cleaner as in the pre-cleaning stage. In this case, the penetrant must be removed from the surface, but not from the defect cavity. The surface is then dried with a lint-free cloth or air jet. When using a cleaner, there is a risk of washing out the penetrant and its incorrect indication.

Application of the developer. After drying, a developer is immediately applied to the OK, usually white, in a thin even layer.

The control. The QA inspection begins immediately after the end of the developing process and ends according to various standards in no more than 30 minutes. The intensity of the color indicates the depth of the defect, the paler the color, the smaller the defect. Have intense coloration deep cracks. After the control, the developer is removed with water or a cleaner.
The coloring penetrant is applied to the surface of the test object (OK). Due to the special qualities that are provided by the selection of certain physical properties of the penetrant: surface tension, viscosity, density, it, under the action of capillary forces, penetrates into the smallest defects that have access to the surface of the test object. The developer, applied to the surface of the test object some time after the penetrant is carefully removed from the surface, dissolves the dye located inside the defect and, due to diffusion, “pulls” the penetrant remaining in the defect onto the surface of the test object. Existing defects are visible enough contrast. Indicator traces in the form of lines indicate cracks or scratches, individual dots indicate pores.

The most convenient dispensers, such as aerosol cans. Developer can also be applied by dipping. Dry developers are applied in a vortex chamber or electrostatically. After applying the developer, you should wait from 5 minutes for large defects, up to 1 hour for small defects. Defects will appear as red marks on a white background.

Through cracks on thin-walled products can be detected by applying the developer and penetrant with different parties products. The dye that has passed through will be clearly visible in the developer layer.

Penetrant (penetrant from English penetrate - to penetrate) called a capillary flaw detection material that has the ability to penetrate into the discontinuities of the test object and indicate these discontinuities. Penetrants contain colorants (color method) or luminescent additives (luminescent method), or a combination of both. Additives make it possible to distinguish the region of the developer layer impregnated with these substances above the crack from the main (most often white) continuous object material without defects (background).

developer (developer) called a flaw detection material designed to extract a penetrant from a capillary discontinuity in order to form a clear indicator pattern and create a background that contrasts with it. Thus, the role of the developer in capillary testing is, on the one hand, to extract the penetrant from defects due to capillary forces, on the other hand, the developer must create a contrasting background on the surface of the controlled object in order to confidently detect colored or luminescent indicator traces of defects. At right technology The width of the trace may exceed the width of the defect by 10–20 or more times, and the brightness contrast increases by 30–50%. This magnifying effect allows experienced technicians to detect very small cracks even with the naked eye.

Sequence of operations for capillary control:

Precleaning	Mechanical, brushed	Inkjet method	Hot steam degreasing	Solvent cleaning
Pre-drying
Penetrant application	bath immersion	Brush application	Aerosol/spray application	Electrostatic application
Intermediate cleaning	Water-soaked, lint-free cloth or sponge	Water-soaked brush	rinse with water	Solvent-impregnated lint-free cloth or sponge
Drying	Air dry	Wipe with a lint-free cloth	Blow clean, dry air	Dry with warm air
Application of developer	By immersion (water-based developer)	Aerosol/spray application (alcohol-based developer)	Electrostatic application (alcohol-based developer)	Applying a dry developer (if the surface is very porous)
Surface inspection and documentation	Control during daytime or artificial lighting min. 500Lux (EN 571-1/ EN3059) When using a fluorescent penetrant: Lighting:< 20 Lux UV intensity: 1000μW/ cm2	Documentation on transparencies	Photo-optical documentation	Documentation by photo or video

The main capillary methods of non-destructive testing are divided into the following depending on the type of penetrating substance:

· The penetrating solution method is a liquid method of capillary non-destructive testing based on the use of a liquid indicator solution as a penetrating agent.

· The filtering suspension method is a liquid method of capillary non-destructive testing based on the use of an indicator suspension as a liquid penetrating agent, which forms an indicator pattern from filtered particles of the dispersed phase.

Capillary methods, depending on the method of revealing the indicator pattern, are divided into:

· Luminescent method, based on registering the contrast of a visible indicator pattern luminescent in long-wave ultraviolet radiation against the background of the surface of the test object;

· contrast (color) method, based on the registration of the contrast of the color in the visible radiation of the indicator pattern against the background of the surface of the test object.

· fluorescent color method, based on the registration of the contrast of a color or luminescent indicator pattern against the background of the surface of the test object in visible or long-wave ultraviolet radiation;

· brightness method, based on the registration of the contrast in the visible radiation of an achromatic pattern against the background of the surface of the test object.

Physical bases of capillary flaw detection. Luminescent flaw detection (LD). Color flaw detection (CD).

There are two ways to change the contrast ratio between the defect image and the background. The first method consists in polishing the surface of the controlled product, followed by etching it with acids. With such processing, the defect is clogged with corrosion products, blackens and becomes noticeable against the light background of the polished material. This method has a number of limitations. In particular, under production conditions, it is completely unprofitable to polish the surface of the product, especially welds. In addition, the method is not applicable to the control of precision polished parts or non-metallic materials. The etching method is more often used to control some local suspicious areas of metal products.

The second method consists in changing the light output of defects by filling them from the surface with special light and color contrast indicator liquids - penetrants. If the penetrant contains luminescent substances, i.e. substances that give a bright glow when irradiated with ultraviolet light, then such liquids are called luminescent, and the control method, respectively, is luminescent (luminescent flaw detection - LD). If the basis of the penetrant are dyes visible at daylight, then the control method is called color (color flaw detection - CD). In color flaw detection, dyes of bright red color are used.

The essence of capillary flaw detection is as follows. The surface of the product is cleaned of dirt, dust, grease, flux residues, paint coatings, etc. After cleaning, a layer of penetrant is applied to the surface of the prepared product and held for some time so that the liquid can penetrate into the open cavities of defects. Then the surface is cleaned from the liquid, part of which remains in the defect cavities.

In the case of luminescent flaw detection the product is illuminated with ultraviolet light (ultraviolet illuminator) in a darkened room and subjected to inspection. Defects are clearly visible in the form of brightly luminous stripes, dots, etc.

With color flaw detection, it is not possible to detect defects at this stage, since the resolution of the eye is too small. To increase the detectability of defects, a special developing material in the form of a quick-drying suspension (for example, kaolin, collodion) or varnish coatings is applied to the surface of the product after removing the penetrant from it. The developing material (usually white in color) pulls the penetrant out of the defect cavity, which leads to the formation of indicator marks on the developer. Indicator traces completely repeat the configuration of defects in the plan, but they are larger in size. Such indicator traces are easily distinguishable by the eye even without the use of optical means. The increase in the size of the indicator trace is the greater, the deeper the defects, i.e. the greater the volume of penetrant that filled the defect, and the more time has passed since the application of the developing layer.

The physical basis of capillary flaw detection methods is the phenomenon of capillary activity, i.e. the ability of a liquid to be drawn into the smallest through holes and channels open at one end.

Capillary activity depends on wetting ability solid body liquid. In any body, molecular cohesive forces act on each molecule from other molecules. They are larger in a solid than in a liquid. Therefore, liquids, unlike solids, do not have the elasticity of the form, but have a large volumetric elasticity. Molecules located on the surface of the body interact both with the body molecules of the same name, tending to draw them into the volume, and with the molecules of the environment surrounding the body and have the greatest potential energy. For this reason, an uncompensated force, called the surface tension force, arises perpendicular to the boundary towards the inside of the body. Surface tension forces are proportional to the length of the wetting contour and naturally tend to reduce it. The liquid on the metal, depending on the ratio of intermolecular forces, will spread over the metal or collect into a drop. A liquid wets a solid if the forces of interaction (attraction) of the liquid with the molecules of the solid are greater than the forces of surface tension. In this case, the liquid will spread over the solid. If the surface tension forces are greater than the forces of interaction with the molecules of the solid, then the liquid will collect into a drop.

When liquid enters the capillary channel, its surface is bent, forming the so-called meniscus. The forces of surface tension tend to reduce the value of the free boundary of the meniscus, and an additional force begins to act in the capillary, leading to the absorption of the wetting liquid. The depth to which a liquid penetrates a capillary is directly proportional to the surface tension of the liquid and inversely proportional to the radius of the capillary. In other words, the smaller the radius of the capillary (defect) and the better the wettability of the material, the faster and deeper the liquid penetrates into the capillary.

Here you can buy materials for capillary control (color flaw detection) at a low price from a warehouse in Moscow: penetrant, developer, cleaner Sherwin, capillary systemsHelling, Magnaflux, ultraviolet lights, ultraviolet lamps, ultraviolet illuminators, ultraviolet lamps and control samples (standards) for color defectoscopy of CD.

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