Corrosion protection system. How to defeat rust: the main ways to protect metal from corrosion. About the standard

INTERSTATE STANDARD

Unified system of protection against corrosion and aging

METALS AND ALLOYS

Methods of determination
corrosion indicators
and corrosion resistance

GOST 9.908-85

MOSCOW
IPK STANDARDS PUBLISHING HOUSE
1999

INTERSTATE STANDARD

Introduction date 01.01.87

This standard establishes the main indicators of corrosion and corrosion resistance (chemical resistance) of metals and alloys with continuous, pitting, intergranular, exfoliating corrosion, spot corrosion, corrosion cracking, corrosion fatigue and methods for their determination. Indicators of corrosion and corrosion resistance are used in corrosion research, testing, inspection of equipment and defect detection of products during production, operation, storage.

1. INDICATORS OF CORROSION AND CORROSION RESISTANCE

1.1. The indicators of corrosion and corrosion resistance of the metal are determined under given conditions, taking into account their dependence on the chemical composition and structure of the metal, the composition of the medium, temperature, hydro- and aerodynamic conditions, the type and magnitude of mechanical stresses, as well as the purpose and design of the product. 1.2. Corrosion resistance indicators can be quantitative, semi-quantitative (point) and qualitative. 1.3. Corrosion resistance should, as a rule, be characterized by quantitative indicators, the choice of which is determined by the type of corrosion and operational requirements. The basis of most of these indicators is the time to reach a given (permissible) degree of corrosion damage to the metal under certain conditions. The indicators of corrosion resistance, primarily the time to reach the allowable depth of corrosion damage, in many cases determine the service life, durability and shelf life of structures, equipment and products. 1.4. The main quantitative indicators of corrosion and corrosion resistance of the metal are given in the table. For a number of corrosion effects (integral corrosion indicators), the corresponding speed (differential) corrosion indicators are given.

Type of corrosion	The main quantitative indicators of corrosion and corrosion resistance
	Corrosion effect (integral corrosion index)	Speed ​​(differential) corrosion index	Corrosion resistance index
continuous corrosion	Corrosion penetration depth	Linear corrosion rate	Corrosion penetration time to the allowable (given) depth*
	Mass loss per unit area	Weight loss rate	Time to reduce the mass by an allowable (specified) value *
stain corrosion	Degree of damage to the surface
Pitting corrosion	Maximum Pitting Depth	Maximum Pitting Penetration Rate	Minimum pit penetration time to allowable (specified) depth*
	Maximum diameter of pitting at the mouth		The minimum time to reach the allowable (specified) size of the diameter of the pitting at the mouth *
	The degree of damage to the surface by pitting		Time to reach the permissible (specified) degree of damage *
Intergranular corrosion			Penetration time to allowable (specified) depth*
	Decreased mechanical properties (relative elongation, narrowing, impact strength, tensile strength)		Time to reduce the mechanical properties to an acceptable (specified) level*
stress corrosion cracking	Depth (length) of cracks	crack growth rate	Time to first crack**
	Decreased mechanical properties (relative elongation, narrowing)		Time to destruction of the sample** Level of safe stresses** (conditional limit of long-term corrosion strength**) Threshold stress intensity factor for corrosion cracking**
Corrosion fatigue	Depth (length) of cracks	crack growth rate	Number of cycles before specimen failure** Conditional corrosion fatigue limit** Threshold stress intensity factor for corrosion fatigue**
exfoliating corrosion	The degree of damage to the surface by delaminations The total length of the ends with cracks
	Corrosion penetration depth	Corrosion penetration rate

With a linear dependence of the corrosion effect on time, the corresponding rate indicator is found by the ratio of the change in the corrosion effect over a certain time interval to the value of this interval. With a non-linear dependence of the corrosion effect on time, the corresponding rate of corrosion is found as the first derivative with respect to time by a graphical or analytical method. 1.5. The corrosion resistance indicators, marked in the table with *, are determined from the time dependence of the corresponding integral corrosion index in a graphical way shown in the diagram, or analytically from its empirical time dependence at= f(t), finding for a valid (given) value at additional the corresponding value of t add. The indicators of corrosion resistance when exposed to mechanical factors, including residual stresses, marked in the table with the sign **, are determined directly during corrosion tests.

Scheme of dependence of the corrosion effect (integral index) at from time

1.6. It is allowed to use, along with the indicators given in the table, other quantitative indicators determined by operational requirements, high sensitivity of experimental methods or the possibility of using them for remote monitoring of the corrosion process, with a preliminary establishment of the relationship between the main and applied indicators. As such indicators of corrosion, taking into account its type and mechanism, the following can be used: the amount of hydrogen released and (or) absorbed by the metal, the amount of oxygen reduced (absorbed), an increase in the mass of the sample (while maintaining solid corrosion products on it), a change in the concentration of corrosion products in medium (with their complete or partial solubility), an increase in electrical resistance, a decrease in reflectivity, a decrease in heat transfer coefficient, a change in acoustic emission, internal friction, etc. For electrochemical corrosion, it is allowed to use electrochemical indicators of corrosion and corrosion resistance. In case of crevice and contact corrosion, the corrosion and corrosion resistance indicators are selected from the table in accordance with the type of corrosion (solid or pitting) in the crevice (gap) or contact zone. 1.7. For one type of corrosion, it is allowed to characterize the results of corrosion tests by several corrosion indicators. In the presence of two or more types of corrosion on one sample (product), each type of corrosion is characterized by its own indicators. Corrosion resistance in this case is evaluated by an indicator that determines the performance of the system. 1.8. If it is impossible or inappropriate to determine quantitative indicators of corrosion resistance, it is allowed to use qualitative indicators, for example, a change in the appearance of the metal surface. At the same time, the presence of tarnishing is visually established; corrosion damage, the presence and nature of the layer of corrosion products; the presence or absence of an undesirable change in the environment, etc. On the basis of a qualitative indicator of corrosion resistance, an assessment is made of the type: resistant - not resistant; good - not good, etc. A change in appearance is allowed to be assessed by points on conditional scales, for example, for electronic equipment products in accordance with GOST 27597. 1.9. Permissible indicators of corrosion and corrosion resistance are set in the regulatory and technical documentation for the material, product, equipment.

2. DETERMINATION OF CORROSION INDICATORS

2.1. Continuous corrosion 2.1.1. Mass loss per unit surface area D m, kg / m 2, calculated by the formula

Where m 0 - mass of the sample before testing, kg; m 1 - mass of the sample after testing and removal of corrosion products, kg; S- sample surface area, m 2 . 2.1.2. When hard-to-remove solid corrosion products are formed or their removal is inexpedient, a quantitative assessment of continuous corrosion is carried out by increasing the mass. The increase in mass per unit surface area is calculated from the difference in the masses of the sample before and after testing, referred to the unit surface area of ​​the sample. To calculate the mass loss of the metal by increasing the mass of the sample, it is necessary to know the composition of the corrosion products. This indicator of metal corrosion in gases at high temperature is determined according to GOST 6130. 2.1.3. Corrosion products are removed according to GOST 9.907. 2.1.4. The change in dimensions is determined by direct measurements from the difference between the dimensions of the sample before and after testing and removal of corrosion products. If necessary, change the dimensions according to the loss of mass, taking into account the geometry of the sample, for example, changing the thickness of a flat sample D L, m, calculated by the formula

Where D m- weight loss per unit area, kg/m 2 ; ρ is the density of the metal, kg/m 3 . 2.2. Spot corrosion 2.2.1. The area of ​​each spot is determined with a planimeter. If such a measurement is not possible, the spot is outlined by a rectangle and its area is calculated. 2.2.2. The degree of damage to the metal surface by corrosion spots ( G) as a percentage is calculated by the formula

Where Si- area i-th spot, m 2; n - the number of spots; S - sample surface area, m 2 . It is allowed to determine the degree of damage to the surface by corrosion with the help of a grid of squares in case of corrosion with spots. 2.3. Pitting corrosion 2.3.1. The maximum penetration depth of pitting corrosion is determined by: measuring the distance between the mouth plane and the bottom of the pitting with a mechanical indicator with a movable needle probe after removing corrosion products in cases where the dimensions of the pitting allow free penetration of the needle probe to its bottom; microscopically, after removal of corrosion products by measuring the distance between the mouth plane and the bottom of the pit (double focusing method); microscopically on a transverse section at an appropriate magnification; sequential mechanical removal of metal layers of a given thickness, for example, by 0.01 mm until the last pits disappear. Pittings with a mouth diameter of at least 10 µm are taken into account. The total area of ​​the working surface must be at least 0.005 m 2 . 2.3.2. A microsection for measuring the maximum penetration depth of pitting corrosion is cut out from the area where the largest pittings are located on the working surface. The cut line should pass through as many of these pits as possible. 2.3.3. The maximum penetration depth of pitting corrosion is found as the arithmetic mean of measurements of the deepest pittings, depending on their number ( n) on the surface: at n < 10 измеряют 1-2 питтинга, при n < 20 - 3-4, при n> 20 - 5. 2.3.4. With through pitting corrosion, the thickness of the sample is taken as the maximum penetration depth. 2.3.5. The maximum diameter of the pitting is determined using measuring instruments or optical means. 2.3.6. The degree of damage to the metal surface by pitting is expressed as a percentage of the surface occupied by pitting. In the presence of a large number of pits with a diameter of more than 1 mm, it is recommended that the degree of damage be determined according to clause 2.2. 2.4. Intergranular corrosion 2.4.1. The depth of intergranular corrosion is determined by the metallographic method according to GOST 1778 on an etched section made in the transverse plane of the sample, at a distance from the edges of at least 5 mm at a magnification of 50 ´ or more. It is allowed to determine the penetration depth of corrosion of aluminum and aluminum alloys on unetched sections. Etching mode - according to GOST 6032, GOST 9.021 and NTD. (Revised edition, Rev. No. 1). 2.4.2. The change in mechanical properties during intergranular corrosion - tensile strength, relative elongation, impact strength - is determined by comparing the properties of metal samples that have been subjected to and not subjected to corrosion. The mechanical properties of metal samples that have not undergone corrosion are taken as 100%. 2.4.3. Samples are made in accordance with GOST 1497 and GOST 11701 when determining the tensile strength and relative elongation, and according to GOST 9454 - when determining impact strength. 2.4.4. It is allowed to use physical methods for controlling the depth of corrosion penetration in accordance with GOST 6032. 2.5. Corrosion cracking and corrosion fatigue 2.5.1. In corrosion cracking and corrosion fatigue, cracks are detected visually or using optical or other flaw detection tools. It is allowed to use indirect measurement methods, for example, determining the increase in the electrical resistance of the sample. 2.5.2. The change in mechanical properties is determined according to clause 2.4.2. 2.6. Exfoliating corrosion 2.6.1. The degree of surface damage during exfoliating corrosion is expressed as a percentage of the area with peeling on each surface of the sample according to GOST 9.904. 2.6.2. The total length of the ends with cracks for each sample ( L) as a percentage is calculated by the formula

Where L i- length of the end section affected by cracks, m; P- sample perimeter, m. 2.6.3. It is allowed to use the conditional scale score according to GOST 9.904 as a generalized semi-quantitative (point) indicator of exfoliating corrosion.

3. DETERMINATION OF INDICATORS OF CORROSION RESISTANCE

3.1. Continuous corrosion 3.1.1. The main quantitative indicators of corrosion resistance against continuous corrosion in the absence of special requirements, for example, in terms of environmental pollution, are determined from the table. 3.1.2. When continuous corrosion occurs at a constant rate, the corrosion resistance indicators are determined by the formulas:

Where tm- time to decrease in mass per unit area by an acceptable value D m, year; v m- weight loss rate, kg / m 2 ∙ year; t 1 - penetration time to the allowable (given) depth ( l), year; v 1 - linear corrosion rate, m/year. 3.1.3. When continuous corrosion occurs at a non-constant rate, the corrosion resistance indicators are determined according to clause 1.5. 3.1.4. If there are special requirements for the optical, electrical and other properties of the metal, its corrosion resistance is estimated by the time of change of these properties to an acceptable (specified) level. 3.2. Stain Corrosion The index of corrosion resistance in spot corrosion is the time (t n) to achieve an acceptable degree of damage to the surface. t value n determined graphically according to clause 1.5. 3.3. Pitting corrosion 3.3.1. The main indicator of corrosion resistance against pitting corrosion is the absence of pitting or the minimum time (t pit) for penetration of pitting to an allowable (given) depth. t pit is determined graphically from the dependence of the maximum pitting depth l max from time. 3.3.2. An indicator of resistance to pitting corrosion can also serve as the time to reach an acceptable degree of damage to the surface by pitting. 3.4. Intercrystalline corrosion 3.4.1. Indices of corrosion resistance against intergranular corrosion are generally determined graphically or analytically from the time dependence of the penetration depth or mechanical properties in accordance with clause 1.5. 3.4.2. A qualitative assessment of resistance against intergranular corrosion of the type of racks - not racks based on accelerated tests of corrosion-resistant alloys and steel is established according to GOST 6032, aluminum alloys - according to GOST 9.021. 3.5. Corrosion cracking 3.5.1. Quantitative indicators of resistance to corrosion cracking are determined for high-strength steels and alloys according to GOST 9.903, for aluminum and magnesium alloys - according to GOST 9.019, welded joints of steel, copper and titanium alloys - according to GOST 26294-84. 3.6. Exfoliating corrosion 3.6.1. The exfoliating corrosion resistance indicators for aluminum and its alloys are determined according to GOST 9.904, for other materials - according to NTD.

4. PROCESSING THE RESULTS

4.1. It is recommended to pre-process the results in order to identify abnormal (outliers) values. 4.2. The dependence of the corrosion effect (integral corrosion index) on time in the case of its monotonous change is recommended to be expressed graphically, using at least four values ​​of the index for plotting. 4.3. The results of the calculation of corrosion and corrosion resistance indicators are recommended to be expressed as a confidence interval of the numerical value of the indicator. 4.4. The regression equation, confidence intervals and accuracy of the analysis are determined according to GOST 20736, GOST 18321. 4.5. The metallographic method for assessing corrosion damage is given in Appendix 1. (Introduced additionally, Rev. No. 1).APPENDIX.(Deleted, Rev. No. 1).

ATTACHMENT 1

Mandatory

METALLOGRAPHIC METHOD FOR ASSESSING CORROSION DAMAGES

1. The essence of the method

The method is based on determining the type of corrosion, the form of corrosion damage, the distribution of corrosion damage in metals, alloys and protective metal coatings (hereinafter referred to as materials) by comparing with the corresponding typical forms, as well as measuring the depth of corrosion damage on a metallographic section.

2. Samples

2.1. The location of sampling from the material under test is selected based on the results of visual (with the naked eye or with a magnifying glass) inspection of the surface or non-destructive flaw detection. 2.2. Samples are cut from the following places in the material: 1) if only part of the surface of the material is affected by corrosion, samples are taken in three places: from the part affected by corrosion; from a part not affected by corrosion, and in the area between them; 2) if there are areas of the surface of the material with different types of corrosion or with different depths of corrosion damage, samples are taken from all areas affected by corrosion; 3) if there is one type of corrosion damage on the surface of the material, samples are taken from at least three characteristic areas of the material under study. 2.3. If necessary, at least one sample is taken from at least five functionally necessary sections of the test material. The size of the sample is determined based on the size of the zone of corrosion damage. 2.4. Samples are cut in such a way that the plane of the section is perpendicular to the surface under study. The manufacturing method should not affect the structure of the material and destroy the surface layer and edges of the sample. For materials with protective coatings, damage to the coating and its separation from the base material is not allowed. 2.5. Sample marking - according to GOST 9.905. 2.6. In the manufacture of a metallographic section, all traces of cutting, for example, burrs, are removed from the surface of the sample. 2.7. When grinding and polishing the section, it is necessary to ensure that the nature and size of the corrosion damage does not change. The edges of the section in the place of corrosion damage should not have roundings. Roundings are allowed that do not affect the accuracy of determining the corrosion damage. To do this, it is recommended to pour the sample into the casting mass in such a way that the edge under study is at a distance of at least 10 mm from the edge of the section. Polishing is carried out for a short time using diamond pastes. 2.8. Evaluation of the section is carried out before and after etching. Etching makes it possible to distinguish between corrosion damage and the structure of the material. When pickling, the nature and size of the corrosion damage should not be changed.

3. Testing

3.1. Determination and assessment of the type of corrosion, the form of corrosion damage and its distribution in the material 3.1.1. The test shall take into account the chemical composition of the material being tested, the method of its processing, as well as any corrosive factors. 3.1.2. The test is carried out on a metallographic section under a microscope at a magnification of 50, 100, 500 and 1000 ´ . 3.1.3. When determining the type of corrosion, the control of corrosion damage is carried out along the entire length of the section. It is allowed to determine several types of corrosion on one sample. 3.1.4. When testing protective coatings, the determination of the type of corrosion of the coating and the base material is carried out separately. 3.1.5. If the material, in addition to the corrosive environment, is also affected by other factors that affect the change in the structure of the material, for example, high temperature, mechanical stress, corrosion damage is determined by comparing the material with a specific sample subjected to the influence of similar factors, but protected from the corrosive environment. 3.1.6. Evaluation of the form of corrosion damage and determination of the type of corrosion is carried out by comparison with typical schemes of corrosion damage according to Appendix 2, the distribution of corrosion damage in the material - according to Appendix 3. 3.2. Measuring the depth of corrosion damage 3.2.1. The depth of corrosion damage is determined on a micrometallographic section using an ocular scale and a micrometer screw of a microscope. 3.2.2. The depth of corrosion damage is determined by the difference in the thickness of the metal of the corroded section of the surface of the section and the surface area without corrosion or by measuring the depth of damage from the surface that is not destroyed or slightly destroyed by corrosion. When testing a material with a protective coating, the results of measuring the depth of corrosion damage to the coating and the base metal are determined separately. 3.2.3. If the entire surface of the sample is affected by corrosion and the depth of corrosion damage in different parts of the surface does not noticeably differ, for example, in the case of intergranular or transgranular corrosion, the depth of corrosion damage is measured in at least 10 areas of the surface. For large samples, measurements are taken at least in 10 areas for every 20 mm of the length of the inspected surface, taking into account the deepest lesions. 3.2.4. In case of local corrosion damage (for example, pitting corrosion or spotting corrosion), measurements are carried out at the places of this corrosion damage, and the number of measurement sites may differ from the requirements given in paragraph 1. 3.2.3. 3.2.5. To clarify the determination of the maximum depth of corrosion damage after the metallographic evaluation of sections, they are re-grinded: until the moment when the measured depth is less than the previous measurement result; 2) for samples with almost the same depth of corrosion damage in different parts of the surface, after evaluation, regrinding is carried out and a new metallographic section is made, on which corrosion damage is again assessed. 3.2.6. The error in measuring the depth of corrosion damage is no more than ±10%.

4. Test report - according to GOST 9.905

ATTACHMENT 1.(Introduced additionally, Amendment No. 1).

APPENDIX 2

Mandatory

TYPES OF CORROSION

Type of corrosion	Characteristics of the form of corrosion damage	Scheme of a typical type of corrosion damage
1. Solid (uniform) corrosion	Forms of corrosion damage 1a and 1b differ only in surface roughness. By changing the shape of the surface before and after the corrosion test, the presence of corrosion is revealed: it is determined by the change in the mass and dimensions of the samples before and after the corrosion test
	Form 1c can be transitional between continuous and selective corrosion, for example, 10c, 10d and 10e The type of corrosion can be specified by changes in its shape depending on the time of exposure to the corrosive environment, as well as by the structure of the metal
2. Local (uneven) corrosion	The shape corresponds to continuous corrosion, but differs in that part of the surface is subject to corrosion or corrosion proceeds at different rates in its individual sections.
3. Corrosion stains	Minor corrosion damage of irregular shape; the size of its area in the case of a small increase may exceed the size of the field of view
4. Corrosion pit	Corrosion damage with a depth approximately equal to the width
5. Pitting corrosion	Corrosion damage with a depth significantly greater than the width
6. Subsurface corrosion	Corrosion damage, characterized by the fact that it occupies a small area on the surface and is mainly concentrated under the surface of the metal
	A form of corrosion damage in which individual zones are below the surface and usually do not have a noticeable direct exit to the surface.
7. Layered corrosion	Corrosion damage, the inner layers of which include grains of various sizes, various phases, inclusions, segregations, etc.
8. Intergranular corrosion	Corrosion damage is characterized by the presence of a corroded zone along the boundaries of metal grains, and it can affect the boundaries of all grains or only individual grains.
9. Transcrystalline corrosion	Corrosion damage is characterized by the presence of a large number of transcrystalline cracks.
10. Selective corrosion	Corrosion damage to which a certain structural phase or component is subjected; if the phase is formed by a eutectic, it is determined whether the whole eutectic or some of its components, for example, cementite, is corroded
	Corrosion damage to which a certain phase of the metal is subjected without direct contact with the corroded surface. In this case, it is determined whether the phases corrode along the grain boundaries or within the grains of the main structure. Next, it is determined whether the boundaries between the corroding phases differ from the rest of the boundaries (the presence of a phase, cracks). From this it is concluded whether the corrosive medium penetrates along the grain boundaries or diffuses through the entire volume of the grains
	Corrosion damage to which only individual grains are subjected, the physical state of which has changed, for example, due to deformation
	Corrosion damage to which only the deformable parts of the grains are subjected, while the resulting corrosion damage zone is narrower than one grain and passes through several grains. At the same time, it is determined whether the deformation has affected the change in the structure of the metal, for example, the transition of austenite to martensite
	Corrosion damage in the form of a zone with rows of isolated inclusions; at the same time, a possible change in the structure in this zone is determined
	Corrosion damage in the form of a wide zone along the grain boundary. This form may be temporary and cannot be attributed to intergranular corrosion; it is characterized by the fact that it does not penetrate into the depth of the metal. More precisely, it can be determined by changes in the form of corrosion damage depending on the time of corrosion exposure and by the release of structural particles in a corroding alloy.
	Corrosion damage, which results in the formation of a new phase of the metallic appearance, which has the ability to reduce the resistance of the metal
	Corrosion damage, as a result of which the chemical composition of the phase changes while maintaining its shape and location, for example, graphitization of cementite plates in cast iron, dezincification of brass, etc. Other corrosion products, for example, oxides, can form in the zone of this change.
11. Corrosion in the form of rare cracks	Corrosion damage, which results in the formation of a deep, slightly branched crack, wide near the surface with a gradual transition to a slight width; crack filled with corrosion products
	Corrosion damage in the form of a deep crack of insignificant width emanating from a corrosion pit on the surface; the crack may have a branched shape
	Corrosion damage, as a result of which an intergranular crack of insignificant width is formed in the absence of corrosion products. Compared to intergranular corrosion, it has the form of single (rare) cracks
	Corrosion damage, as a result of which a transcrystalline crack of insignificant width with significant branching is formed. Compared to transcrystalline corrosion, it has the form of single (rare) cracks. Some cracks may be partly transgranular and partly intergranular.
	Corrosion damage, as a result of which cracks of insignificant width are formed, having the form of threads, mainly parallel to the surface and creating a zone of a certain depth. They cannot be attributed to similar cracks formed due to deformation or poor processing of the sample.
	Corrosion damage in the form of small, predominantly short cracks inside individual grains. Cracks can be formed, for example, due to the action of molecular hydrogen, high stress, corrosion of a certain phase

APPENDIX E 2.(Introduced additionally, Amendment No. 1).

APPENDIX 3

Mandatory

DISTRIBUTION OF CORROSION

APPENDIX 3(Introduced additionally, Amendment No. 1).

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR State Committee for Product Quality Management and StandardsDEVELOPERSL.I. Topchiashvili, G.V. Kozlova, cand. tech. sciences (topic leaders); V.A. Atanova, G.S. Fomin, cand. chem. Sciences, L.M. Samoilova, I.E. Trofimova 2. APPROVED AND INTRODUCED BY Decree of the USSR State Committee for Standards dated October 31, 1985 No. 3526 3. The standard fully complies with ST SEV 4815-84, ST SEV 6445-88 4. INTRODUCED FOR THE FIRST TIME 5. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

	Item number, applications		Item number, applications
GOST 9.019-74	3.5.1	GOST 6032-89	2.4.1; 2.4.4; 3.4.2
GOST 9.021-74	2.4.1; 3.4.2	GOST 6130-71	2.1.2
GOST 9.903-81	3.5.1	GOST 9454-78	2.4.3
GOST 9.904-82	2.6.1; 2.6.3; 3.6.1	GOST 11701-84	2.4.3
GOST 9.905-82	Attachment 1	GOST 18321-73	4.4
GOST 9.907-83	2.1.3	GOST 20736-75	4.4
GOST 1497-84	2.4.3	GOST 26294-84	3.5.1
GOST 1778-70	2.4.1	GOST 27597-88	1.8

6. REPUBLICATION with Amendment No. 1 approved in October 1989 (IUS 2-90)

The development of the steel industry is inextricably linked with the search for ways and means to prevent the destruction of metal products. Corrosion protection, development of new methods is a continuous process in the technological chain of production of metal and metal products. Iron-containing products become unusable under the influence of various physical and chemical external environmental factors. We see these effects in the form of hydrated iron residues, that is, rust.

Methods for protecting metals from corrosion are selected depending on the operating conditions of the products. Therefore stands out:

• Corrosion associated with atmospheric phenomena. This is a destructive process of oxygen or hydrogen depolarization of the metal. Which leads to the destruction of the crystal molecular lattice under the influence of a humid air environment and other aggressive factors and impurities (temperature, the presence of chemical impurities, etc.).
• Corrosion in water, primarily marine. In it, the process is faster due to the content of salts and microorganisms.
• The processes of destruction that occur in the soil. Soil corrosion is a rather complex form of metal damage. Much depends on the composition of the soil, humidity, heating and other factors. In addition, products, such as pipelines, are buried deep in the ground, which makes it difficult to diagnose. And corrosion often affects individual areas pointwise or in the form of ulcerative veins.

Types of corrosion protection are selected individually, based on the environment in which the protected metal product will be located.

Typical types of rust damage

Methods for protecting steel and alloys depend not only on the type of corrosion, but also on the type of destruction:

• Rust covers the surface of the product in a continuous layer or in separate sections.
• It appears in the form of spots and penetrates deep into the detail.
• Destroys the metal molecular lattice in the form of a deep crack.
• In a steel product consisting of alloys, one of the metals is destroyed.
• Deeper extensive rusting, when not only the surface is gradually broken, but penetration into the deeper layers of the structure occurs.

Damage types can be combined. Sometimes it is difficult to determine them immediately, especially when there is a point destruction of steel. Corrosion protection methods include special diagnostics to determine the extent of damage.

Allocate chemical corrosion without the occurrence of electric currents. In contact with petroleum products, alcohol solutions and other aggressive ingredients, a chemical reaction occurs, accompanied by gas emissions and high temperature.

Electrochemical corrosion is when a metal surface comes into contact with an electrolyte, specifically water from the environment. In this case, the diffusion of metals occurs. Under the influence of the electrolyte, an electric current arises, the substitution and movement of the electrons of the metals that enter the alloy occurs. The structure is destroyed, rust is formed.

Steel smelting and its corrosion protection are two sides of the same coin. Corrosion causes great harm to industrial and commercial buildings. In cases with large-scale technical structures, for example, bridges, power transmission poles, barrier structures, it can also provoke man-made disasters.

Corrosion of metal and methods of protection against it

How to protect metal? Corrosion of metals and ways to protect against it, there are many. To protect the metal from rust, industrial methods are used. In domestic conditions, various silicone enamels, varnishes, paints, polymeric materials are used.

Industrial

The protection of iron from corrosion can be divided into several main areas. Corrosion protection methods:

• Passivation. Upon receipt of steel, other metals are added (chromium, nickel, molybdenum, niobium and others). They are distinguished by high quality characteristics, refractoriness, resistance to aggressive media, etc. As a result, an oxide film is formed. Such types of steel are called alloyed.

• Surface coating with other metals. Different methods are used to protect metals from corrosion: electroplating, immersion in a molten composition, application to the surface using special equipment. As a result, a metallic protective film is formed. Chromium, nickel, cobalt, aluminum and others are most often used for these purposes. Alloys (bronze, brass) are also used.

• The use of metal anodes, protectors, more often from magnesium alloys, zinc or aluminum. As a result of contact with the electrolyte (water), an electrochemical reaction begins. The protector breaks down and forms a protective film on the steel surface. This technique has proven itself well for the subsea parts of ships and offshore drilling rigs.

• Acid pickling inhibitors. The use of substances that reduce the level of environmental impact on the metal. They are used for conservation, storage of products. And also in the oil refining industry.

• Corrosion and protection of metals, bimetals (cladding). This coating of steel is a layer of another metal or a composite composition. Under the influence of pressure and high temperatures, diffusion and bonding of surfaces occur. For example, well-known bimetal heating radiators.

Corrosion of metal and methods of protection against it, used in industrial production, are quite diverse, these are chemical protection, glass enamel coating, enameled products. Steel is hardened at high, over 1000 degrees, temperatures.

In the video: galvanizing metal as protection against corrosion.

household

Protecting metals from corrosion at home is, first of all, chemistry for the production of paints and varnishes. The protective properties of the compositions are achieved by combining various components: silicone resins, polymeric materials, inhibitors, metal powder and shavings.

To protect the surface from rust, it is necessary to use special primers or a rust converter before painting, especially on older structures.

What are the types of converters?

• Primers - provide adhesion, adhesion to metal, level the surface before painting. Most of them contain inhibitors that significantly slow down the corrosion process. Preliminary application of a primer layer can significantly save paint.
• Chemical compounds - convert iron oxide into other compounds. They are not subject to rust. They are called stabilizers.
• Compounds that convert rust into salts.
• Resins and oils that bind and seal rust, thus neutralizing it.

The composition of these products includes components that slow down the process of rust formation as much as possible. Converters are included in the product line of manufacturers producing paints for metal. They are different in terms of their texture.

It is better to choose a primer and paint from the same company so that they are suitable in terms of chemical composition. First you need to decide which methods you will choose to apply the composition.

Protective paints for metal

Paints for metal are divided into heat-resistant, which can be operated at high temperatures, and for normal temperatures up to eighty degrees. The following main types of paints for metal are used: alkyd, acrylic, epoxy paints. There are special anti-corrosion paints. They are two- or three-component. They are mixed immediately before use.

Advantages of paintwork for metal surfaces:

• well protect surfaces from temperature changes and atmospheric fluctuations;
• quite easily applied in different ways (brush, roller, using an airbrush);
• most of them are quick-drying;
• wide range of colors;
• long operating periods.

Of the available inexpensive means, you can use the usual silver. It contains aluminum powder, which creates a protective film on the surface.

Epoxy two-component compounds are suitable for protecting metal surfaces that are subjected to increased mechanical stress, in particular the underbody of cars.

Metal protection at home

Corrosion, methods of protection against it in domestic conditions require compliance with a certain sequence:

1. Before applying a primer or rust converter, the surface is thoroughly cleaned of dirt, oil stains, rust. Use metal brushes or special attachments for grinders.

2. Then a primer layer is applied, allowed to soak and dry.

Protecting metals from corrosion is a complex process. It begins at the stage of steel smelting. It is difficult to list all the rust control methods, as they are constantly being improved, not only in industry, but also for domestic use. Manufacturers of paints and varnishes are constantly improving the compositions, increasing their corrosive properties. All this significantly extends the service life of metal structures and steel products.

Electrochemical protection of metal structures from corrosion manifestations is based on the imposition of a negative potential on the protected product. It demonstrates a high level of efficiency in cases where metal structures are subjected to active electrochemical destruction.

1 The essence of anti-corrosion electrochemical protection

Any metal structure begins to break down over time as a result of corrosion. For this reason, metal surfaces are necessarily coated with special compounds consisting of various inorganic and organic elements before use. Such materials reliably protect the metal from oxidation (rust) for a certain period. But after a while they need to be updated (apply new compounds).

When the protective layer cannot be renewed, corrosion protection of pipelines, car body and other structures is carried out using an electrochemical technique. It is indispensable for rust protection of tanks and containers operating underground, the bottoms of sea ships, various underground utilities, when the potential for corrosion (it is called free) is in the zone of overpassivation of the base metal of the product or its active dissolution.

The essence of electrochemical protection is that a constant electric current is connected to a metal structure from the outside, which forms a cathode-type polarization of microgalvanic electrodes on the surface of the metal structure. As a result, the transformation of anodic regions into cathodic regions is observed on the metal surface. After such a transformation, the negative influence of the environment is perceived by the anode, and not by the material from which the protected product is made.

Electrochemical protection can be either cathodic or anodic. At the cathode potential of the metal is shifted to the negative side, at the anode - to the positive.

2 Cathodic electrical protection - how does it work?

The mechanism of the process, if you understand it, is quite simple. A metal immersed in an electrolytic solution is a system with a large number of electrons, which includes cathode and anode zones separated in space, electrically closed to each other. This state of affairs is due to the heterogeneous electrochemical structure of metal products (for example, underground pipelines). Corrosion manifestations are formed on the anode areas of the metal due to its ionization.

When a material with a high potential (negative) is attached to the base metal in the electrolyte, the formation of a common cathode is observed due to the process of polarization of the cathode and anode zones. In this case, a large potential is understood to be such a value that exceeds the potential of the anodic reaction. In the formed galvanic couple, the material with a low potential of the electrode dissolves, which leads to the suspension of corrosion (since the ions of the protected metal product cannot enter the solution).

Required to protect the body of the car, underground tanks and pipelines, the bottoms of ships, the electric current can come from an external source, and not just from the functioning of a microgalvanic couple. In such a situation, the protected structure is connected to the "minus" of the electric current source. The anode, made of materials with a low degree of solubility, is connected to the "plus" of the system.

If the current is obtained only from galvanic couples, one speaks of a process with sacrificial anodes. And when using current from an external source, we are talking about the protection of pipelines, parts of vehicles and water vehicles using superimposed current. The use of any of these schemes provides high-quality protection of the object from general corrosion decay and from a number of its special variants (selective, pitting, cracking, intergranular, contact types of corrosion).

3 How does the anodic technique work?

This electrochemical technique for protecting metals from corrosion is used for structures made of:

• carbon steels;
• passivated dissimilar materials;
• highly alloyed and;
• titanium alloys.

The anode scheme assumes a shift in the potential of the protected steel in a positive direction. Moreover, this process continues until the system enters a stable passive state. Such corrosion protection is possible in environments that conduct electrical current well. The advantage of the anodic technique is that it significantly slows down the rate of oxidation of the protected surfaces.

In addition, such protection can be carried out by saturating the corrosive environment with special oxidizing components (nitrates, bichromates, and others). In this case, its mechanism is approximately identical to the traditional method of anodic polarization of metals. Oxidizing agents significantly increase the effect of the cathodic process on the steel surface, but they usually negatively affect the environment by releasing aggressive elements into it.

Anode protection is used less frequently than cathodic protection, since a lot of specific requirements are put forward for the protected object (for example, the impeccable quality of welds in pipelines or a car body, the constant presence of electrodes in solution, etc.). Cathodes in anode technology are arranged according to a strictly defined scheme, which takes into account all the features of the metal structure.

For the anode technique, sparingly soluble elements are used (cathodes are made of them) - platinum, nickel, stainless high-alloy alloys, lead, tantalum. The installation itself for such corrosion protection consists of the following components:

• protected structure;
• current source;
• cathode;
• special reference electrode.

It is allowed to use anode protection for tanks where mineral fertilizers, ammonia compounds, sulfuric acid are stored, for cylindrical installations and heat exchangers operated at chemical enterprises, for tanks in which chemical nickel plating is performed.

4 Features of tread protection of steel and metal

Quite often used version of cathodic protection is the technology of using special protector materials. With a similar technique, an electronegative metal is connected to the structure. During a given time period, corrosion affects the protector, and not the protected object. After the protector is destroyed to a certain level, a new "protector" is put in its place.

Protective electrochemical protection is recommended for processing objects located in soil, air, water (that is, in chemically neutral environments). At the same time, it will be effective only when there is some transitional resistance between the medium and the protective material (its value varies, but in any case it is small).

In practice, protectors are used when it is economically inexpedient or physically impossible to supply the required charge of electric current to an object made of steel or metal. It is worth noting separately the fact that protective materials are characterized by a certain radius, to which their positive effect extends. For this reason, it is necessary to correctly calculate the distance to remove them from the metal structure.

Popular protectors:

• Magnesium. They are used in environments with a pH of 9.5–10.5 units (earth, fresh and low-salt water). Manufactured from magnesium-based alloys with additional alloying with aluminum (no more than 6–7%) and zinc (up to 5%). For the environment, such protectors that protect objects from corrosion are potentially unsafe due to the fact that they can cause cracking and hydrogen embrittlement of metal products.
• Zinc. These "protectors" are indispensable for structures operating in water with a high salt content. It makes no sense to use them in other media, since hydroxides and oxides appear on their surface in the form of a thick film. Zinc-based protectors contain minor (up to 0.5%) additions of iron, lead, cadmium, aluminum and some other chemical elements.
• Aluminum. They are used in sea running water and at facilities located on the coastal shelf. Aluminum protectors contain magnesium (about 5%) and zinc (about 8%), as well as very small amounts of thallium, cadmium, silicon, and indium.

In addition, iron protectors are sometimes used, which are made from iron without any additives or from ordinary carbon steels.

5 How is the cathode scheme performed?

Temperature fluctuations and ultraviolet rays cause serious damage to all external components and components of vehicles. Protection of the car body and some of its other elements from corrosion by electrochemical methods is recognized as a very effective way to extend the ideal appearance of the car.

The principle of operation of such protection is no different from the scheme described above. When protecting the car body from rusting, the anode function can be performed by almost any surface that is capable of high-quality conduction of electric current (wet road surface, metal plates, steel structures). The cathode is directly the body of the vehicle.

Elementary methods of electrochemical protection of the car body:

1. We connect through the mounting wire and an additional resistor to the plus of the battery the garage housing in which the car is standing. This protection against corrosion of the car body is especially productive in the summer, when there is a greenhouse effect in the auto garage. This effect just protects the outer parts of the car from oxidation.
2. We mount a special grounding metallized "tail" made of rubber in the rear of the vehicle so that drops of moisture fall on it while driving in rainy weather. At high humidity, a potential difference is formed between the highway and the car body, which protects the outer parts of the vehicle from oxidation.

Also, the protection of the car body is carried out with the help of protectors. They are mounted on the thresholds of the car, on the bottom, under the wings. Protectors in this case are small plates made of platinum, magnetite, carboxyl, graphite (anodes that do not break down over time), as well as aluminum and stainless steel (they should be changed every few years).

6 Nuances of anti-corrosion protection of pipelines

Pipe systems are currently protected by draining and cathodic electrochemical techniques. When protecting pipelines from corrosion according to the cathodic scheme, the following are used:

• External current sources. Their plus will be connected to the anode ground, and the minus to the pipe itself.
• Protective anodes using current from galvanic pairs.

The cathodic technique assumes the polarization of the protected steel surface. At the same time, underground pipelines are connected to the "minus" of the cathodic protection complex (in fact, it is a current source). "Plus" is connected to an additional external electrode using a special cable, which is made of conductive rubber or graphite. This scheme allows you to get a closed circuit, which includes the following components:

• electrode (outer);
• electrolyte in the soil where pipelines are laid;
• pipes directly;
• cable (cathode);
• current source;
• cable (anodic).

For tread protection of pipelines, materials based on aluminum, magnesium and zinc are used, the efficiency of which is 90% when using protectors based on aluminum and zinc and 50% for protectors made of magnesium alloys and pure magnesium.

For drainage protection of pipe systems, the technology of diverting stray currents into the ground is used. There are four options for drainage piping - polarized, earth, reinforced and straight. With direct and polarized drainage, jumpers are placed between the "minus" of stray currents and the pipe. For an earth protection circuit, it is necessary to make earthing by means of additional electrodes. And with enhanced drainage of pipe systems, a converter is added to the circuit, which is necessary to increase the magnitude of the drainage current.

Foreword

The goals, basic principles and basic procedure for carrying out work on interstate standardization are established by GOST 1.0-92 “Interstate standardization system. Basic Provisions” and GOST 1.2-97 “Interstate Standardization System. Interstate standards, rules and recommendations for interstate standardization. The order of development, adoption, application, updating and cancellation "

About the standard

1. DEVELOPED by the Technical Committee for Standardization TK 214 "Protection of Products and Materials from Corrosion" (GUP of the Order of the Red Banner of Labor Academy of Public Utilities named after K.D. Pamfilov, GUP VNYI of Railway Transport, FSUE VNII Standard)

2. INTRODUCED by the Federal Agency for Technical Regulation and Metrology

3. ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 27 of June 22, 2005)

Short name of the country according to MK (ISO3166)004-97	Country code according to MK (ISO 3166) 004-97	Abbreviated name of the national standards body
Azerbaijan	AZ	Azstandard
Armenia	AM	Ministry of Trade and Economic Development of the Republic of Armenia
Belarus	BY	State Standard of the Republic of Belarus
Kazakhstan	KZ	State Standard of the Republic of Kazakhstan
Kyrgyzstan	KG	Kyrgyzstandart
Moldova	MD	Moldova-Standard
the Russian Federation	EN	Federal Agency for Technical Regulation and Metrology
Tajikistan	TJ	Tajikstandart
Turkmenistan	TM	Main State Service "Turkmenstandartlary"
Uzbekistan	USD	Uzstandard

4. This International Standard takes into account the main normative provisions of ISO/IEC Guide 21:1999 "Adoption of International Standards as Regional or National Standards".

(ISO/IEC Guide 21:1999 "Regional or national adoption of international standards deliverables")

5. By order of the Federal Agency for Technical Regulation and Metrology dated October 25, 2005 No. 262-st, the interstate standard GOST 9.602-2005 was put into effect directly as a national standard of the Russian Federation from January 1, 2007.

6. REPLACE GOST 9.602-89

Information on the entry into force (termination) of this standard and amendments to it is published in the index "National Standards".

Information about changes to this standard is published in the index "National standards", and the text of the changes - in the information indexes "National standards". In case of revision or cancellation of this standard, the relevant information will be published in the information index "National Standards"

Preface Information about the standard Introduction General requirements for corrosion protection 1. Scope 2. Normative references 3. General provisions 4. Corrosion hazard criteria 5 Selection of corrosion protection methods 6. Requirements for protective coatings and quality control methods 7. Requirements for electrochemical protection 8. Requirements for limiting leakage currents at sources of stray currents 9. Requirements for performing work on anti-corrosion protection Appendix A (reference) Determination of soil electrical resistivity (reference) Determination of the dangerous influence of stray direct current Appendix D (reference) Determination of the presence of stray currents in the ground Appendix F (reference) Determination of the presence of current in underground communication facilities Appendix G (reference) Application I (reference) Determination of adhesion of protective coatings Appendix K (reference) Determination of adhesion of a coating to steel after soaking in water Appendix L (reference) Determination of the peeling area of ​​protective coatings at cathodic polarization H (reference) Determination of indentation resistance Appendix P (reference) Coatings for protection against external corrosion of pipelines of heating networks and conditions for their laying Appendix P (reference) Measurement of polarization potentials during electrochemical protection Appendix C (reference) Determination of the total potential of a structure under electrochemical protection Annex T (reference) Measurement of the potential of the pipeline of the channel laying in the electrochemical protection of pipelines with the location of the anode ground in the channel Appendix U (reference) Determination of the minimum polarity rational protective potential of underground steel pipelines by displacement from the stationary potential Bibliography

Introduction

Underground metal pipelines, cables and other structures are one of the most capital-intensive sectors of the economy. The life support of cities and settlements depends on their normal, uninterrupted functioning.

The greatest influence on the operating conditions and service life of underground metal structures is exerted by the corrosive and biocorrosive aggressiveness of the environment, as well as stray direct currents, the source of which is rail electrified transport, and alternating currents of industrial frequency.

The impact of each of these factors, and even more so their combination, can reduce the service life of steel underground structures by several times and lead to the need for premature relaying of obsolete pipelines and cables.

The only possible way to combat this negative phenomenon is the timely application of measures for the anti-corrosion protection of steel underground structures.

This standard takes into account the latest scientific and technical developments and achievements in the practice of anti-corrosion protection, accumulated by operating, construction and design organizations.

This standard specifies corrosion hazard criteria and methods for their determination; requirements for protective coatings, their quality standards for different operating conditions of underground structures (insulation adhesion to the pipe surface, adhesion between coating layers, cracking resistance, impact resistance, resistance to UV radiation, etc.) and methods for assessing the quality of coatings; requirements for electrochemical protection are regulated, as well as methods for monitoring the effectiveness of anti-corrosion protection.

The introduction of this standard will increase the service life and reliability of underground metal structures, reduce the cost of their operation and overhaul.

INTERSTATE STANDARD

Unified system of corrosion and aging protection Underground structures General requirements for corrosion protection Unified system of corrosion and aging protection. Underground constructions. General requirements for corrosion protection

Introduction date - 2007-01-01

Application area

This standard establishes general requirements for corrosion protection of the outer surface of underground metal structures (hereinafter referred to as structures): pipelines and tanks (including trench type) made of carbon and low alloy steels, power cables with voltage up to 10 kV inclusive; communication and signaling cables in a metal sheath, steel structures of unattended amplifying (NUP) and regeneration (NRP) points of communication lines, as well as requirements for objects that are sources of stray currents, including electrified rail transport, DC transmission lines through the “wire -ground", industrial enterprises consuming direct current for technological purposes.

The standard does not apply to the following structures: communication cables with a hose-type protective cover; reinforced concrete and cast iron structures; communications laid in tunnels, buildings and sewers; piles, sheet piles, columns and other similar metal structures; main pipelines transporting natural gas, oil, oil products, and branches from them; pipelines of compressor, pumping and pumping stations, oil depots and head facilities of oil and gas fields; installations for complex treatment of gas and oil; pipelines of heating networks with polyurethane foam thermal insulation and a pipe-shell made of rigid polyethylene (pipe-in-pipe design) with an operating system for remote monitoring of the state of pipeline insulation; metal structures located in permafrost soils.

GOST 9.048-89 Unified system of protection against corrosion and aging. Technical products. Laboratory test methods for mold resistance

GOST 9.049-91 Unified system of protection against corrosion and aging. Polymeric materials and their components. Laboratory test methods for mold resistance

GOST 12.0.004-90 Occupational safety standards system. Organization of labor safety training. General provisions

GOST 12.1.003-83 Occupational safety standards system. Noise. General safety requirements

GOST 12.1.005-88 System of labor safety standards. General sanitary and hygienic requirements for the air of the working area

GOST 12.2.004-75 System of labor safety standards. Machines and mechanisms special for pipeline construction. Safety requirements

GOST 12.3.005-75 System of labor safety standards. Painting works. General safety requirements

GOST 12.3.008-75 System of labor safety standards. Production of metallic and non-metallic inorganic coatings. General safety requirements

GOST 12.3.016-87 System of labor safety standards. Construction. Anti-corrosion works. Safety requirements

GOST 12.4.026-76 1) System of labor safety standards. Signal colors and safety signs

GOST 112-78 Meteorological glass thermometers. Specifications

GOST 411-77 Rubber and glue. Methods for determining the bond strength with metal during peeling

GOST 427-75 Measuring metal rulers. Specifications

GOST 1050-88 Rolled section calibrated with a special surface finish from quality carbon structural steel. General specifications

GOST 2583-92 Batteries from cylindrical manganese-zinc cells with saline electrolyte. Specifications

GOST 2678-94 Roll roofing and waterproofing materials. Test Methods

GOST 2768-84 Technical acetone. Specifications

GOST 4166-76 Sodium sulfate. Specifications

GOST 4650-80 Plastics. Methods for determining water absorption

GOST 5180-84 Soils. Methods for laboratory determination of physical characteristics.

GOST 5378-88 Goniometers with vernier. Specifications

GOST 6055-86 2) Water. Unit of stiffness

GOST 6323-79 Wires with PVC insulation for electrical installations. Specifications

GOST 6456-82 Grinding paper skin. Specifications

GOST 6709-72 Distilled water. Specifications.

GOST 7006-72 Protective cable covers. Design and types, specifications and test methods

GOST 8711-93 (IEC51-2-84) Direct-acting analog indicating electrical measuring instruments and auxiliary parts to them. Part 2: Particular requirements for ammeters and voltmeters

GOST 9812-74 Oil insulating bitumen. Specifications

GOST 11262-80 Plastics. Tensile test method.

GOST 12026-76 Laboratory filter paper. Specifications

GOST 13518-68 Plastics. Method for determining the resistance of polyethylene to stress cracking.

GOST 14236-81 Polymer films. Tensile test method.

GOST 14261-77 High purity hydrochloric acid. Specifications.

GOST 15140-78 Paintwork materials. Methods for determining adhesion.

GOST 16337-77 High pressure polyethylene. Specifications

GOST 16783-71 Plastics. Method for determining the brittleness temperature during compression of a sample folded in a loop

GOST 22261-94 Instruments for measuring electrical and magnetic quantities. General specifications

GOST 25812-83 3) Main steel pipelines. General requirements for corrosion protection

GOST 29227-91 (ISO 835-1-81) Laboratory glassware. Pipettes graduated. Part 1. General requirements.

Note: When using this standard, it is advisable to check the validity of the reference standards according to the "National Standards" index, compiled as of January 1 of the current year, and according to the corresponding information indexes published in the current year. If the reference standard is replaced (modified), then when using this standard, you should be guided by the replaced (modified) standard. If the referenced standard is canceled without replacement, the provision in which the reference to it is given applies to the extent that this reference is not affected.

1) In the Russian Federation, GOST R 12.4.026-2001 “System of labor safety standards. Signal colors, safety signs and signal markings. Purpose and rules of application. General technical requirements and characteristics. Test Methods".

2) In the Russian Federation, GOST R 52029-2003 “Water. Unit of hardness.

3) In the Russian Federation, GOST R 51164-98 “Main steel pipelines. General requirements for corrosion protection”.

General provisions

3.1. The requirements of this standard are taken into account in the design, construction, reconstruction, repair, operation of underground structures, as well as objects that are sources of stray currents. This standard is the basis for the development of regulatory documents (RD) for the protection of specific types of underground metal structures and measures to limit stray currents (leakage currents).

3.2. Corrosion protection means (materials and design of coatings, cathodic protection stations, devices for monitoring the quality of insulating coatings and determining the risk of corrosion and the effectiveness of anticorrosion protection) are used only that meet the requirements of this standard and have a certificate of conformity.

3.3. When developing a project for the construction of structures, they simultaneously develop a project for protecting them from corrosion.

Note: For signaling, interlocking and blocking (SCB), power and communication cables used on the railway, when it is not possible to determine the parameters of electrochemical protection at the design development stage, it is allowed to develop working drawings of electrochemical protection after laying the cables based on measurement data and trial switching on of protective devices within the time limits established by the RD.

3.4. Corrosion protection measures for buildings under construction, operating and reconstructed structures are provided for in protection projects in accordance with the requirements of this standard.

In projects for the construction and reconstruction of structures that are sources of stray currents, measures are taken to limit leakage currents.

3.5. All types of corrosion protection provided for by the construction project are accepted into operation before the facilities are put into operation. During the construction process for underground steel gas pipelines and liquefied gas tanks, electrochemical protection is put into effect in areas of dangerous stray current influence no later than one month, and in other cases no later than six months after the structure is laid in the ground; for communication facilities - no later than six months after their laying in the ground.

It is not allowed to put into operation objects that are sources of stray currents until all the measures provided for by the project to limit these currents have been carried out.

3.6. The protection of structures against corrosion is carried out so as not to impair protection against electromagnetic influences and lightning strikes.

3.7. During the operation of structures, the effectiveness of anti-corrosion protection and the risk of corrosion are systematically monitored, as well as the registration and analysis of the causes of corrosion damage.

3.8. Work on the repair of failed electrochemical protection installations is qualified as emergency.

3.9. Structures are equipped with control and measuring points (CIP).

Viewing devices (wells) are used to control the corrosion state of communication cables laid in cable ducts.

Corrosion Hazard Criteria

4.1. Criteria for the danger of corrosion of structures are:

Corrosive aggressiveness of the environment (soils, groundwater and other waters) in relation to the metal of the structure (including biocorrosive aggressiveness of soils);

Dangerous action of stray direct and alternating currents.

4.2. To assess the corrosive aggressiveness of the soil in relation to steel, the specific electrical resistance of the soil, measured in the field and laboratory conditions, and the average density of the cathode current are determined at a potential shift of 100 mV more negative than the stationary potential of steel in the soil (table 1). If, when determining one of the indicators, a high corrosive aggressiveness of the soil is established (and for reclamation structures - medium), then the other indicator is not determined.

Methods for determining the electrical resistivity of the soil and the average density of the cathode current are given in Appendices A and B, respectively.

Notes

1. If the electrical resistivity of the soil, measured under laboratory conditions, is equal to or more than 130 Ohm m, the corrosive aggressiveness of the soil is considered low and the average cathode current density z K is not evaluated.

2. The corrosive aggressiveness of the soil in relation to the steel armor of communication cables, steel structures of the NUP is evaluated only by the specific electrical resistance of the soil, determined in the field (see Table 1).

3. The corrosive aggressiveness of the soil in relation to the steel of pipes of thermal networks of channelless laying is evaluated by the specific electrical resistance of the soil, determined in the field and laboratory conditions (see table 1).

4. For pipelines of heating networks laid in channels, thermal chambers, manholes, etc., the criterion for the risk of corrosion is the presence of water or soil in the channels (thermal chambers, manholes, etc.), when water or soil reaches thermal insulation structure or pipeline surface.

Table 1

table 2

Table 3

Table 4

Table 5

Requirements for protective coatings and quality control methods

6.1. The designs of protective coatings of very reinforced and reinforced types used to protect steel underground pipelines, except for heat pipelines, are shown in table 6; coating requirements - in tables 7 and 8, respectively.

Other designs of protective coatings may be used to ensure that the requirements of this standard are met.

6.2. During the construction of pipelines, welded pipe joints, fittings (hydraulic seals, condensate collectors, elbows, etc.) and places of damage to the protective coating are insulated under pipeline conditions with the same materials as the pipelines, or others, in terms of their protective properties that meet the requirements given in table 7 , not inferior to the coating of the linear part of the pipe and having adhesion to the coating of the linear part of the pipeline.

6.3. When repairing pipelines in operation, it is allowed to use coatings similar to those applied to the pipeline earlier, as well as based on heat-shrinkable materials, polymer-bitumen, polymer-asmol and sticky polymer tapes, except for polyvinyl chloride.

Note: For insulation of joints and repair of damaged areas of pipelines with mastic bitumen coatings, the use of polyethylene tapes is not allowed.

6.4. For steel tanks installed in the ground or bunded with soil, protective coatings of a very reinforced type of construction No. 5 and 7 are used according to table 6.

Table 6

Table 7

Requirements for highly reinforced coatings

Name of indicator 1)	Meaning	Test method	Coating number according to table 6
1. Adhesion to steel, not less, at temperature		Annex I, Method A
20˚С, N/cm	70,0
	50,0
	35,0		1 (for pipelines with a diameter up to 820 mm), 9
	20,0		3, 4, 5, 6, 10
40˚С, N/cm	35,0
	20,0		1, 9
	10,0		3, 4, 10
20˚С, MPa (kg/cm 2)	0,5 (5,0)	Annex I, method B	7, 8
2. Adhesion in the overlap at a temperature of 20˚С, N/cm, not less than:		Annex I, Method A
Tapes to tape	7,0		3, 4, 5
	35,0
	20,0
Tape wrappers	5,0
Layer of extruded polyolefin to tape	15,0
3. Adhesion to steel after soaking in water for 1000 hours at a temperature of 20ºС, N/cm, not less than	50,0	Annex K	1 (for pipelines with a diameter of 820 mm or more)
	35,0		1, 2 (for pipelines up to 820 mm in diameter)
	30,0
	15,0		3, 4
4. Impact strength, not less, at temperature:		According to GOST 25812, Appendix 5
From minus 15ºС to minus 40ºС, J			For all coatings (except 1, 2, 3.9), for pipelines with a diameter, mm, not more than:
	5,0
	7,0
	9,0
20ºС, J/mm coating thickness			1, 2, 3, 9 for pipelines with a diameter, mm:
	4,25		Up to 159
	5,0		Up to 530
	6,0		St. 530
			2 for pipelines with a diameter, mm:
	8,0		From 820 to 1020
	10,0		From 1220 and more
5. Tensile strength, MPa, not less, at a temperature of 20º 2)	12,0	GOST 11262	1, 2, 9
	10,0	GOST 14236	3, 8, 10
6. Coating peeling area at cathodic polarization, cm 2 , not more, at temperature:		Annex L
20ºС	5,0		For all coatings
40ºС	8,0		1, 2, 9
7. Resistance to stress cracking at a temperature of 50ºС, h, not less than		According to GOST 13518	For coatings with a polyolefin layer thickness of at least 1 mm: 1, 2, 3, 8, 9, 10
8. Resistance to UV radiation in a flow of 600 kWh/m at a temperature of 50ºС, h, not less		According to GOST 16337	1, 2, 3, 8
9. Brittleness temperature, ºС, not higher	-50ºС	According to GOST 16783	4, 9
10. Temperature of fragility of the mastic layer (flexibility on the rod) ºС, no more	-15ºС	According to GOST 2678-94	5, 6, 8, 10
11. Transient electrical resistance of the coating in a 3% solution of Na 2 SO 4 at a temperature of 20ºС, Ohm m 2, not less than:		Annex M
initial	10 10		1, 2, 9
	10 8		3, 4, 5, 6, 7, 8, 10
After 100 days. excerpts	10 9		1, 2, 9
	10 7		3, 4, 5, 6, 7, 8, 10
12. Transient electrical resistance of the coating 3) on the completed pipeline sections (in pits) at temperatures above 0˚С, Ohm m 2, not less than	5 10 5	Annex M	1, 2, 3, 8, 9, 10
	2 10 5		4, 5, 6
	5 10 4
13. Dielectric continuity (absence of breakdown at electric voltage), kV/mm	5,0	Spark flaw detector	1, 2, 3, 4, 5, 6, 8, 9, 10
	4,0
14. Resistance to penetration (indentation), mm, no more, at temperature:		Annex H	For all coatings
Up to 20˚С	0,2
Over 20˚С	0,3
15. Water saturation for 24 hours,%, no more	0,1	According to GOST 9812	5, 6, 7, 8, 10
16. Mushroom resistance, points, not less		According to GOST 9.048, GOST 9.049	For all types of coatings of a very reinforced type.
1) Properties are measured at 20°C unless otherwise specified in the RD. 2) The tensile strength of combined coatings, tapes and protective wraps (in megapascals) refers only to the thickness of the carrier polymer base, excluding the thickness of the mastic or rubber sublayer, while the tensile strength, related to the total thickness of the tape, must be at least 50 N / cm of width, and protective wrapping - not less than 80 N/cm of width. 3) The maximum permissible value of the transient electrical resistance of the coating on underground pipelines operated for a long time (more than 40 years) should be at least 50 Ohm m 2 - for polymer coatings.

Table 8

Requirements for reinforced coatings

Name of indicator 1)	Meaning	Test method	Coating number according to table 6
1 Adhesion to steel at 20°C:
N/cm, not less	50,0	Annex I, Method A	11 (for pipelines with a diameter of 820 mm or more) -
	35,0		11 (for pipelines up to 820 mm in diameter) -
	20,0
MPa (kgf / cm 2), not less than	0,5 (5,0)	Annex I, method B
Point, no more		According to GOST 15140	14, 15
2 Adhesion in the overlap at a temperature of 20 °C, N/cm, not less than:		Annex I, Method A
tape to tape	7,0
layer of extruded polyethylene to the tape	15,0
3 Adhesion to steel after soaking in water for 1000 hours at 20°C:
N/cm, not less	50,0	Annex K	11 (for pipelines with a diameter of 820 mm or more)
	35,0		11 (for pipelines with a diameter up to 820 mm)
	15,0
score, no more		According to GOST 15140	14, 15
4 Impact strength, not less, at temperature:		According to GOST 25812, Appendix 5
from minus 15 °С to plus 40 °С, J	2,0
	6,0		13/H^
	8,0		15,16
20 °C, J/mm coating thickness			11, 12 for pipelines with a diameter:
	4.25		up to 159 mm
	5,0		up to 530 mm
	6,0		St. 530 mm
5 Tensile strength, MPa, not less, at 20 °C 2)
12,0	According to GOST 11262
	10,0	According to GOST 14236
6 Coating peeling area at cathodic polarization, cm 2 , no more, at temperature:		Annex L
20°C	4,0		14, 15, 16
	5,0		11, 12, 13
40°C	8,0		11, 15, 16
7 Resistance to stress cracking at temperature		According to GOST 13518	For coatings with a polyolefin layer thickness of at least 1 mm:
50°С, h, not less			11,12
8 Resistance to UV radiation in a flow of 600 kWh/m at a temperature of 50 °C, h, not less than		According to GOST 16337
		11, 12
9 Transient electrical resistance of the coating in 3% solution of Na 2 SO 4 at a temperature of 20 °C, Ohm-m 2 , not less than:		Annex M
initial	10 10
	10 8		12, 13, 15, 16
	5 10 2
after 100 days exposure	10 9
	10 7		12,13,15,16
	3 10 2
10 Transient electrical resistance of the coating 3) on the completed pipeline section (in pits) at temperatures above 0°C, Ohm m 2 , not less than	3 10 5	Annex M	11, 12, 16
	1 10 5
	5 10 4
11 Dielectric continuity (no breakdown at electrical voltage), kV/mm	5,0	Spark flaw detector	11, 12, 16
	4,0
	2,0
12. Water saturation for 24 hours, %, no more	0,1	According to GOST 9812
13. Fungus resistance, score, not less		According to GOST 9.048, GOST 9.049	For all reinforced coatings
1) Properties are measured at 20°C unless otherwise specified in the RD. 2) The tensile strength of the combined coating, tapes and protective wraps (in megapascals) refers only to the thickness of the carrier polymer base, without taking into account the thickness of the mastic or rubber sublayer. At the same time, the tensile strength, related to the total thickness of the tape, must be at least 50 N/cm of width, and of the protective wrapper - at least 80 N/cm of width. 3) The maximum permissible value of the transient electrical resistance of the coating on underground pipelines operated for a long time (more than 40 years) should be at least 50 Ohm-m 2 for mastic bitumen coatings and at least 200 Ohm-m 2 for polymer coatings.

6.5. The thickness of protective coatings is controlled by non-destructive testing using thickness gauges and other measuring instruments:

In basic and factory conditions for two-layer and three-layer polymer coatings based on extruded polyethylene, polypropylene; combined based on polyethylene tape and extruded polyethylene; tape polymeric and mastic coatings - on every tenth pipe of one batch at least at four points around the circumference of the pipe and in places of doubt;

In route conditions for mastic coatings - by 10% of welded joints of pipes, insulated manually, at four points along the circumference of the pipe;

On tanks for mastic coatings - at one point on each square meter of the surface, and in places of inflections of insulating coatings - after 1 m along the circumference,

6.6. The adhesion of protective coatings to steel is controlled using adhesive meters:

In basic and factory conditions - every 100m or on every tenth pipe in the batch;

In highway conditions - by 10% of welded joints of pipes insulated manually;

On tanks - at least at two points along the circumference,

For mastic coatings, it is allowed to determine adhesion by cutting an equilateral triangle with a side length of at least 4.0 cm, followed by peeling off the coating from the top of the notch angle. Adhesion is considered satisfactory if, when peeling off new coatings, more than 50% of the area of ​​the peeled mastic remains on the pipe metal. The coating damaged during the adhesion test shall be repaired in accordance with the RD.

6.7. The continuity of the pipe coatings after the end of the insulation process under basic and factory conditions is controlled over the entire surface with a spark flaw detector at a voltage of 4.0 or 5.0 kV per 1 mm of coating thickness (depending on the coating material), and for silicate-enamel - 2 kV per 1 mm of thickness, as well as on the route before lowering the pipeline into the trench and after the isolation of the tanks.

6.8. Defective places, as well as through damage to the protective coating, identified during its quality check, are corrected before backfilling the pipeline. During repair, uniformity, solidity and continuity of the protective coating are ensured; after correction, the repaired places are subject to a secondary inspection.

6.9. After backfilling the pipeline, the protective coating is checked for the absence of external damage that causes direct electrical contact between the pipe metal and the soil, using devices to detect insulation damage.

6.10. To protect pipelines of heating networks from external corrosion, protective coatings are used, the designs and conditions of use of which are given in Appendix P.

Requirements for electrochemical protection

7.1. Requirements for electrochemical protection in the absence of a dangerous effect of direct stray and alternating currents

7.1.1. The cathodic polarization of structures (except for pipelines transporting media heated above 20 ° C) is carried out in such a way that the polarization potentials of the metal relative to the saturated copper sulfate reference electrode are between the minimum and maximum (in absolute value) values ​​in accordance with Table 9.

Measurement of polarization potentials is carried out in accordance with Appendix P.

Table 9

Requirements for electrochemical protection in the presence of a dangerous influence of direct stray currents

7.2.1. Protection of structures from the dangerous influence of direct stray currents is carried out in such a way as to ensure the absence of anode and alternating zones on the structure.

The total duration of positive displacements of the potential relative to the stationary potential is allowed no more than 4 minutes per day.

The determination of potential displacements (the difference between the measured potential of the structure and the stationary potential) is carried out in accordance with Appendix D.

These methods can be divided into 2 groups. The first 2 methods are usually implemented before the start of the production operation of a metal product (the choice of structural materials and their combinations at the stage of designing and manufacturing a product, applying protective coatings to it). The last 2 methods, on the contrary, can be carried out only during the operation of the metal product (passing current to achieve a protective potential, introducing special additives-inhibitors into the technological environment) and are not associated with any pre-treatment prior to use.

The second group of methods allows, if necessary, to create new protection modes that provide the least corrosion of the product. For example, in certain sections of the pipeline, depending on the aggressiveness of the soil, it is possible to change the density of the cathode current. Or for different grades of oil pumped through pipes, use different inhibitors.

Q: How are corrosion inhibitors applied?

Answer: To combat the corrosion of metals, corrosion inhibitors are widely used, which are introduced in small amounts into an aggressive environment and create an adsorption film on the metal surface, which slows down electrode processes and changes the electrochemical parameters of metals.

Question: What are the ways to protect metals from corrosion using paints and varnishes?

Answer: Depending on the composition of the pigments and the film-forming base, paint coatings can act as a barrier, passivator or protector.

Barrier protection is the mechanical isolation of a surface. Violation of the integrity of the coating, even at the level of the appearance of microcracks, predetermines the penetration of an aggressive medium to the base and the occurrence of under-film corrosion.

Passivation of the metal surface with the help of LCP is achieved by chemical interaction of the metal and coating components. This group includes primers and enamels containing phosphoric acid (phosphating), as well as compositions with inhibitory pigments that slow down or prevent the corrosion process.

Metal protector protection is achieved by adding powder metals to the coating material, which create donor electron pairs with the protected metal. For steel, these are zinc, magnesium, aluminum. Under the action of an aggressive environment, the additive powder gradually dissolves, and the base material does not corrode.

Question: What determines the durability of metal protection against corrosion by paints and varnishes?

Answer: Firstly, the durability of metal protection against corrosion depends on the type (and kind) of the applied paintwork. Secondly, the decisive role is played by the thoroughness of the preparation of the metal surface for painting. The most time-consuming process in this case is the removal of corrosion products formed earlier. Special compounds are applied that destroy rust, followed by their mechanical removal with metal brushes.

In some cases, rust removal is almost impossible to achieve, which implies the widespread use of materials that can be applied directly to surfaces damaged by corrosion - rust coatings. This group includes some special primers and enamels used in multi-layer or independent coatings.

Question: What are highly filled two-component systems?

Answer: These are anti-corrosion paints and varnishes with a reduced solvent content (the percentage of volatile organic substances in them does not exceed 35%). In the market for home use materials, one-component materials are mainly offered. The main advantage of highly filled systems compared to conventional systems is a significantly better corrosion resistance with a comparable layer thickness, less material consumption and the possibility of applying a thicker layer, which ensures that the necessary anticorrosion protection is obtained in just 1-2 times.

Question: How to protect the surface of galvanized steel from destruction?

Answer: Solvent-based anticorrosive primer based on modified vinyl-acrylic resins "Galvaplast" is used for interior and exterior works on bases made of ferrous metals with scale removed, galvanized steel, galvanized iron. The solvent is white spirit. Application - brush, roller, spray. Consumption 0.10-0.12 kg / sq.m; drying 24 hours.

Q: What is patina?

Answer: The word "patina" refers to a film of various shades that forms on the surface of copper and copper-containing alloys under the influence of atmospheric factors during natural or artificial aging. Patina is sometimes referred to as oxides on the surface of metals, as well as films that cause tarnishing over time on the surface of stones, marble or wooden objects.

The appearance of a patina is not a sign of corrosion, but rather a natural protective layer on the copper surface.

Question: Is it possible to artificially create a patina on the surface of copper products?

Answer: Under natural conditions, a green patina is formed on the surface of copper within 5-25 years, depending on the climate and the chemical composition of the atmosphere and precipitation. At the same time, copper carbonates are formed from copper and its two main alloys - bronze and brass: bright green malachite Cu 2 (CO 3) (OH) 2 and azure blue azurite Cu 2 (CO 3) 2 (OH) 2. For zinc-containing brass, the formation of green-blue rosasite of the composition (Cu,Zn) 2 (CO 3) (OH) 2 is possible. Basic copper carbonates can be easily synthesized at home by adding an aqueous solution of soda ash to an aqueous solution of a copper salt, such as copper sulphate. At the same time, at the beginning of the process, when there is an excess of copper salt, a product is formed that is closer in composition to azurite, and at the end of the process (with an excess of soda) - to malachite.

Saving coloring

Question: How to protect metal or reinforced concrete structures from the influence of an aggressive environment - salts, acids, alkalis, solvents?

Answer: To create chemical-resistant coatings, there are several protective materials, each of which has its own area of ​​protection. The widest range of protection has: XC-759 enamels, ELOKOR SB-022 varnish, FLK-2, primers, XC-010, etc. In each individual case, a specific color scheme is selected, according to the operating conditions. Tikkurilla Coatings Temabond, Temacoat and Temachlor paints.

Question: What compositions can be used for painting the internal surfaces of tanks for kerosene and other petroleum products?

Answer: Temaline LP is a two-component epoxy gloss paint with an amino adduct hardener. Application - brush, spray. Drying 7 hours.

EP-0215 ​​is a primer for corrosion protection of the inner surface of caisson tanks operating in a fuel medium with an admixture of water. It is applied on surfaces made of steel, magnesium, aluminum and titanium alloys, operated in various climatic zones, at elevated temperatures and exposed to polluted environment.

Suitable for use with BEP-0261 primer and BEP-610 enamel.

Question: What compositions can be used for the protective coating of metal surfaces in marine and industrial environments?

Answer: Thick-film type paint based on chlorinated rubber is used for painting metal surfaces in marine and industrial environments subject to moderate chemical attack: bridges, cranes, conveyors, port equipment, tank exteriors.

Temacoat HB is a two-component modified epoxy paint used for priming and painting metal surfaces exposed to atmospheric, mechanical and chemical attack. Application - brush, spray. Drying 4 hours.

Question: What compositions should be used to cover difficult-to-clean metal surfaces, including those immersed in water?

Answer: Temabond ST-200 is a two-component modified epoxy paint with aluminum pigmentation and low solvent content. It is used for painting bridges, tanks, steel structures and equipment. Application - brush, spray. Drying - 6 hours.

Temaline BL is a two-component, solvent-free epoxy coating. It is used for painting steel surfaces subject to wear, chemical and mechanical attack when immersed in water, containers for oil or gasoline, tanks and reservoirs, sewage treatment plants. Application - airless spray.

Temazinc is a one component zinc rich epoxy paint with a polyamide hardener. Used as a primer in epoxy, polyurethane, acrylic, chlorinated rubber paint systems for steel and cast iron surfaces exposed to strong atmospheric and chemical attack. It is used for painting bridges, cranes, steel frames, steel structures and equipment. Drying 1 hour.

Question: How to protect underground pipes from fistula formation?

Answer: There can be two reasons for the breakthrough of any pipes: mechanical damage or corrosion. If the first reason is the result of accident and carelessness - the pipe is hooked on something or the weld is broken, then corrosion cannot be avoided, this is a natural phenomenon caused by soil moisture.

In addition to the use of special coatings, there is a protection widely used throughout the world - cathodic polarization. It is a direct current source that provides a polar potential of min 0.85 V, max - 1.1 V. It consists of just a conventional AC voltage transformer and a diode rectifier.

Q: How much does cathodic polarization cost?

Answer: The cost of cathodic protection devices, depending on their design, ranges from 1000 to 14 thousand rubles. A repair team can easily check the polarization potential. Installation of protection is also not expensive and does not involve labor-intensive earthworks.

Protection of galvanized surfaces

Question: Why can't galvanized metals be shot blasted?

Answer: Such preparation violates the natural corrosion resistance of the metal. Surfaces of this kind are treated with a special abrasive agent - round glass particles that do not destroy the protective layer of zinc on the surface. In most cases, it is sufficient to simply treat with an ammonia solution to remove grease stains and zinc corrosion products from the surface.

Question: How to repair a damaged zinc coating?

Answer: Zinc-filled compositions ZincKOS, TsNK, "Vinikor-zinc", etc., which are applied by cold galvanizing and provide anodic protection of the metal.

Question: How is metal protection performed using CNC (zinc-rich compositions)?

Answer: The technology of cold galvanizing with the use of ZNK guarantees absolute non-toxicity, fire safety, heat resistance up to +800°C. The coating of metal with this composition is carried out by spraying, roller or even just a brush and provides the product, in fact, double protection: both cathodic and film. The term of such protection is 25-50 years.

Question: What are the main advantages of the "cold galvanizing" method over hot galvanizing?

Answer: This method has the following advantages:

1. Maintainability.
2. Possibility of drawing in the conditions of a construction site.
3. There are no restrictions on the overall dimensions of protected structures.

Question: At what temperature is thermal diffusion coating applied?

Answer: Application of thermal diffusion zinc coating is carried out at temperatures from 400 to 500°C.

Question: Are there any differences in the corrosion resistance of a coating obtained by thermal diffusion zinc plating compared to other types of zinc coatings?

Answer: The corrosion resistance of thermal diffusion zinc coating is 3-5 times higher than that of galvanized coating and 1.5-2 times higher than the corrosion resistance of hot zinc coating.

Question: What paintwork materials can be used for protective and decorative painting of galvanized iron?

Answer: To do this, you can use both water-based - G-3 primer, G-4 paint, and solvent-based - EP-140, ELOKOR SB-022, etc. Tikkurila Coatings protective systems can be used: 1 Temacoat GPLS-Primer + Temadur, 2 Temaprime EE + Temalac, Temalac and Temadur are tinted according to RAL and TVT.

Question: What kind of paint can gutter and drainage galvanized pipes be painted with?

Answer: Sockelfarg is a black and white water-based latex paint. Designed for application to both new and previously painted outdoor surfaces. Resistant to weather conditions. The solvent is water. Drying 3 hours.

Question: Why are water-based corrosion protection products rarely used?

Answer: There are 2 main reasons: the increased price compared to conventional materials and the opinion in certain circles that water systems have inferior protective properties. However, as environmental legislation tightens, both in Europe and around the world, the popularity of water systems is growing. Experts who tested high-quality water-based materials were able to make sure that their protective properties are not worse than those of traditional materials containing solvents.

Question: What device is used to determine the thickness of the paint film on metal surfaces?

Answer: The most easy-to-use device "Konstanta MK" - it measures the thickness of the paintwork on ferromagnetic metals. Much more functions are performed by the multifunctional thickness gauge "Constant K-5", which measures the thickness of conventional paintwork, galvanic and hot-zinc coatings on both ferromagnetic and non-ferromagnetic metals (aluminum, its alloys, etc.), and also measures surface roughness, temperature and air humidity, etc.

Rust recedes

Question: How can you treat objects that are heavily corroded by rust?

Answer: The first recipe: a mixture of 50 g of lactic acid and 100 ml of vaseline oil. The acid converts iron metahydroxide from rust into an oil-soluble salt, iron lactate. The cleaned surface is wiped with a cloth moistened with vaseline oil.

The second recipe: a solution of 5 g of zinc chloride and 0.5 g of potassium hydrotartrate dissolved in 100 ml of water. Zinc chloride in an aqueous solution undergoes hydrolysis and creates an acidic environment. Iron metahydroxide dissolves due to the formation of soluble iron complexes with tartrate ions in an acidic medium.

Question: How to unscrew a rusted nut with improvised means?

Answer: A rusted nut can be moistened with kerosene, turpentine, or oleic acid. After a while, she manages to turn it off. If the nut "persists", you can set fire to the kerosene or turpentine with which it was moistened. This is usually sufficient to separate the nut and bolt. The most radical way: a very hot soldering iron is applied to the nut. The metal of the nut expands and the rust lags behind the threads; now a few drops of kerosene, turpentine or oleic acid can be poured into the gap between the bolt and the nut. This time, the nut will definitely loosen!

There is another way to separate rusty nuts and bolts. A “cup” of wax or plasticine is made around the rusted nut, the rim of which is 3-4 mm higher than the level of the nut. Dilute sulfuric acid is poured into it and a piece of zinc is placed. After a day, the nut will easily turn off with a wrench. The fact is that a cup with acid and metallic zinc on an iron base is a miniature galvanic cell. The acid dissolves the rust and the iron cations formed are reduced on the zinc surface. And the metal of the nut and bolt does not dissolve in acid as long as it has contact with zinc, since zinc is a more chemically active metal than iron.

Question: What compositions applied on rust are produced by our industry?

Answer: Domestic solvent-borne compositions applied “over rust” include well-known materials: primer (some manufacturers produce it under the name “Inkor”) and primer-enamel “Gremirust”. These two-component epoxy paints (base + hardener) contain corrosion inhibitors and targeted additives, allowing them to be applied to dense rust up to 100 microns thick. The advantages of these primers are: curing at room temperature, the possibility of applying to a partially corroded surface, high adhesion, good physical and mechanical properties and chemical resistance, ensuring long-term operation of the coating.

Question: What can be used to paint old rusty metal?

Answer: For dense rust, it is possible to use several paints and varnishes containing rust converters:

• primer G-1, primer-paint G-2 (water-borne materials) – at temperatures up to +5°;
• primer-enamel ХВ-0278, primer-enamel AS-0332 – up to minus 5°;
• primer-enamel "ELOKOR SB-022" (materials based on organic solvents) - up to minus 15°C.
• Primer-enamel Tikkurila Coatings, Temabond (tinted according to RAL and TVT)

Question: How to stop the process of metal rusting?

Answer: This can be done with the help of "stainless primer". The primer can be used both as an independent coating on steel, cast iron, aluminum, and in a coating system that includes 1 primer layer and 2 enamel layers. It is also used for priming corroded surfaces.

"Nerjamet-primer" works on the metal surface as a rust converter, chemically binding it, and the resulting polymer film reliably isolates the metal surface from atmospheric moisture. When using the composition, the total cost of repair and restoration work on repainting metal structures is reduced by 3-5 times. The soil is produced ready for use. If necessary, it must be diluted to working viscosity with white spirit. The drug is applied to metal surfaces with remnants of tightly adhering rust and scale with a brush, roller, spray gun. Drying time at +20° - 24 hours.

Question: Roofing often fades. What kind of paint can be used for painting galvanized roofs and gutters?

Answer: Stainless steel cyclone. The coating provides long-term protection against weather, humidity, UV radiation, rain, snow, etc.

Possesses high covering ability and light fastness, does not fade. Significantly extends the service life of galvanized roofs. Also Tikkurila Coatings, Temadur and Temalac coatings.

Question: Can chlorinated rubber paints protect metal from rust?

Answer: These paints are made from chlorinated rubber dispersed in organic solvents. According to their composition, they are volatile resin and have high water and chemical resistance. Therefore, it is possible to use them for corrosion protection of metal and concrete surfaces, water pipes and tanks. Temanil MS-Primer + Temachlor system can be used from Tikkuril Coatings materials.

Anticorrosive in the bath, bathroom, pool

Question: What kind of coating can be used to protect bath containers for cold drinking and hot washing water from corrosion?

Answer: For containers for cold drinking and washing water, KO-42 paint is recommended;, Epovin for hot water - ZincKOS and Teplokor PIGMA compositions.

Question: What are enameled pipes?

Answer: In terms of chemical resistance, they are not inferior to copper, titanium and lead, and at cost are several times cheaper. The use of enameled pipes made of carbon steels instead of stainless steels gives a tenfold cost savings. The advantages of such products include greater mechanical strength, including in comparison with other types of coatings - epoxy, polyethylene, plastic, as well as higher abrasion resistance, which makes it possible to reduce the diameter of pipes without reducing their throughput.

Question: What are the features of re-enamelling bathtubs?

Answer: Enameling can be done with a brush or spray with the participation of professionals, as well as with a brush yourself. Preliminary preparation of the surface of the bath is to remove the old enamel and clean the rust. The whole process takes no more than 4-7 hours, another 48 hours the bath dries, and you can use it after 5-7 days.

Re-enamelling bathtubs require special care. Such baths cannot be washed with powders such as Comet and Pemolux, or using products containing acid, such as Silit. It is unacceptable to get varnishes on the surface of the bath, including for hair, the use of bleach when washing. Such baths are usually cleaned with soaps: washing powders or dishwashing detergents applied to a sponge or soft cloth.

Question: What paintwork materials can be used to re-enamel bathtubs?

Answer: Composition "Svetlana" includes enamel, oxalic acid, hardener, tinting pastes. The bath is washed with water, etched with oxalic acid (stains, stone, dirt, rust are removed and a rough surface is created). Washed with washing powder. Chips close up in advance. Then enamel should be applied within 25-30 minutes. When working with enamel and hardener, contact with water is not allowed. The solvent is acetone. Bath consumption - 0.6 kg; drying - 24 hours. Fully gaining properties after 7 days.

You can also use two-component epoxy-based paint Tikkurila "Reaflex-50". When using glossy bath enamel (white, tinted), either washing powders or laundry soap are used for cleaning. Fully gaining properties after 5 days. Consumption per bath - 0.6 kg. The solvent is industrial alcohol.

B-EP-5297V is used to restore the enamel coating of bathtubs. This paint is glossy, white, tinting is possible. The finish is smooth, even and durable. Do not use abrasive powders of the “Sanitary” type for cleaning. Fully gaining properties after 7 days. Solvents - a mixture of alcohol with acetone; R-4, No. 646.

Question: How to protect against breakage of steel reinforcement in the swimming pool bowl?

Answer: If the condition of the ring drainage of the pool is unsatisfactory, softening and suffusion of the soil is possible. The penetration of water under the bottom of the tank can cause subsidence of the soil and the formation of cracks in concrete structures. In these cases, the reinforcement in the cracks can corrode to breakage.

In such complex cases, the reconstruction of damaged reinforced concrete structures of the reservoir should include the implementation of a protective sacrificial layer of shotcrete on the surfaces of reinforced concrete structures exposed to the leaching action of water.

Obstacles to biodegradation

Question: What external conditions determine the development of wood-destroying fungi?

Answer: The most favorable conditions for the development of wood-destroying fungi are: the presence of air nutrients, sufficient wood moisture and favorable temperature. The absence of any of these conditions will delay the development of the fungus, even if it is firmly established in the wood. Most fungi develop well only at high relative humidity (80-95%). When wood moisture is below 18%, the development of fungi practically does not occur.

Question: What are the main sources of wood moisture and what is their danger?

Answer: The main sources of wood moisture in the structures of various buildings and structures include ground (underground) and surface (storm and seasonal) water. They are especially dangerous for wooden elements of open structures located in the ground (pillars, piles, power transmission line and communication supports, sleepers, etc.). Atmospheric moisture in the form of rain and snow threatens the ground part of open structures, as well as the outer wooden elements of buildings. Operational moisture in a drop-liquid or vapor form in residential premises is present in the form of household moisture released during cooking, washing, drying clothes, washing floors, etc.

A large amount of moisture is introduced into the building when laying raw wood, applying masonry mortars, concreting, etc. For example, 1 sq.m of laid wood with a moisture content of up to 23%, when dried to 10-12%, releases up to 10 liters of water.

The wood of buildings, which dries out naturally, is in danger of decay for a long time. If chemical protection measures were not provided, it, as a rule, is affected by the house fungus to such an extent that the structures become completely unusable.

Condensation moisture that occurs on the surface or in the thickness of structures is dangerous because, as a rule, it is detected already when irreversible changes have occurred in the enclosing wooden structure or its element, for example, internal decay.

Question: Who are the "biological" enemies of the tree?

Answer: These are mold, algae, bacteria, fungi and antimycetes (this is a cross between fungi and algae). Almost all of them can be dealt with with antiseptics. The exception is fungi (saprophytes), since antiseptics act only on some of their species. But it is fungi that are the cause of such widespread rot, which is the most difficult to deal with. Professionals divide rot by color (red, white, gray, yellow, green and brown). Red rot affects conifers, white and yellow - oak and birch, green - oak barrels, as well as wooden beams and cellar ceilings.

Question: Are there ways to neutralize white house fungus?

Answer: White house fungus is the most dangerous enemy of wooden structures. The rate of destruction of wood by white house fungus is such that in 1 month it completely "eats" a four-centimeter oak floor. Previously, in the villages, if the hut was affected by this fungus, it was immediately burned to save all other buildings from infection. After that, the whole world built a new hut for the affected family in another place. Currently, in order to get rid of white house fungus, the affected area is dismantled and burned, and the rest is impregnated with 5% chromic (5% solution of potassium dichromate in 5% sulfuric acid), while it is recommended to cultivate the land on 0.5 m deep.

Question: What are the ways to protect the wood from rotting in the early stages of this process?

Answer: If the process of decay has already begun, it can only be stopped by thorough drying and ventilation of wooden structures. In the early stages, disinfectant solutions, for example, such as the antiseptic compositions "Wood Doctor", can help. They are available in three different versions.

Grade 1 is intended for the prevention of wooden materials immediately after their purchase or immediately after the construction of the house. The composition protects against fungus and woodworm.

Grade 2 is used if fungus, mold or "blue" has already appeared on the walls of the house. This composition destroys existing diseases and protects against their future manifestations.

Grade 3 is the most powerful antiseptic, it completely stops the process of decay. More recently, a special composition (grade 4) has been developed for insect control - “anti-bug”.

SADOLIN Bio Clean is a disinfectant for surfaces contaminated with mold, moss, algae, based on sodium hypochlorite.

DULUX WEATHERSHIELD FUNGICIDAL WASH is a highly effective mold, lichen and rot killer. These compounds are used both indoors and outdoors, but they are effective only in the early stages of rot control. In case of serious damage to wooden structures, rotting can be stopped by special methods, but this is a rather difficult job, usually performed by professionals with the help of restoration chemicals.

Question: What protective impregnations and preservative compositions, presented on the domestic market, prevent biocorrosion?

Answer: Of the Russian antiseptic preparations, it is necessary to mention metacid (100% dry antiseptic) or polysept (25% solution of the same substance). Such conservation compositions as "BIOSEPT", "KSD" and "KSD" have proven themselves well. They protect the wood from damage by mold, fungi, bacteria, and the last two, in addition, make the wood difficult to ignite. Texture coatings "AQUATEX", "SOTEKS" and "BIOX" eliminate the occurrence of fungus, mold and wood blue. They are breathable and have a durability of over 5 years.

A good domestic material for wood protection is GLIMS-LecSil glazing impregnation. This is a ready-to-use aqueous dispersion based on styrene-acrylate latex and reactive silane with modifying additives. At the same time, the composition does not contain organic solvents and plasticizers. Glazing sharply reduces the water absorption of wood, as a result of which it can even be washed, including with soap and water, prevents fire impregnation from washing out, due to antiseptic properties it destroys fungi and mold and prevents their further formation.

Of the imported antiseptic compounds for protecting wood, antiseptics from TIKKURILA have proven themselves well. Pinjasol Color is an antiseptic that forms a continuous water-repellent and weather-resistant finish.

Question: What are insecticides and how are they used?

Answer: To combat beetles and their larvae, poisonous chemicals are used - contact and intestinal insecticides. Fluoride and silicofluoride sodium are allowed by the Ministry of Health and have been used since the beginning of the last century; when using them, safety measures must be observed. To prevent damage to wood by a bug, preventive treatment with fluorosilicic compounds or a 7-10% solution of common salt is used. During historical periods of widespread wooden construction, all wood was processed at the harvesting stage. Aniline dyes were added to the protective solution, which changed the color of the wood. In old houses, to this day, you can find red beams.

The material was prepared by L. RUDNITSKY, A. ZHUKOV, E. ABISHEV

 

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