JB/T 6743-1993 Technical requirements for corrosion protection of indoor and outdoor steel cable trays
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T 6743-1993
Technical requirements for corrosion protection of indoor and outdoor steel cable trays
Published on August 21, 1993
Ministry of Machinery Industry of the People's Republic of China
Standard Download Network (www.bzxzw.com))
Implementation on October 1, 1993
Mechanical Industry Standard of the People's Republic of China
Technical requirements for corrosion protection of indoor and outdoor steel cable trays
Subject content and scope of application
JB/T67431993
This standard specifies the environmental conditions, corresponding protection types, technical requirements, test methods and inspection rules for steel cable trays (hereinafter referred to as cable trays) used in various indoor and outdoor environments. This standard applies to steel cable trays used in general environments, hot and humid environments, and indoor and outdoor corrosive environments. Cited standards
JB4375
ZBK04001
GB2423.33
GB2423.17
GB2423.16
National standards
GB1720
GB1732
CECS31:91
Environmental conditions for application of electric and electronic productsFixed use in weather-protected locationsEnvironmental conditions for application of electric and electronic productsFixed use in weather-free locationsElectrical productsEnvironmental conditions for use in indoor and outdoor corrosive locationsEnvironmental technical requirements for indoor and outdoor anti-corrosion electric productsBasic environmental test procedures for electric and electronic productsBasic environmental test procedures for electric and electronic productsBasic environment for electric and electronic products Test procedures Basic environmental test procedures for electrical and electronic products Basic environmental test procedures for electrical and electronic products Test Kch; High concentration sulfur dioxide corrosive gas test method Test Db: Alternating damp heat test method
Test Ka: Salt spray test method
Test A: Low temperature test method
Test J: Mildew test method
Artificial climate accelerated test methods for plastics, coatings, and rubber materials Paint film adhesion test method
Paint film impact resistance test method
Steel cable tray engineering design specification
Environmental conditions and protection types for use
The environmental conditions and protection types for use of cable trays are classified according to climatic conditions (K), biological conditions (B) and chemically active substance conditions (C).
One means indoor or outdoor conditions; 4 means outdoor conditions. 3
The conditions for chemically active substances are divided into three severity levels: light corrosion (C2), medium corrosion (C3) and strong corrosion (C4). 3.2 The protection type of a product refers to the corresponding measures taken to adapt to an environment of a certain degree of severity, and the type of product designed and manufactured refers to the ability of the product to adapt to the environment. The protection types of cable trays and the corresponding levels of environmental conditions for use are specified in Table 1. The code for the protection type should be clearly marked on the product manual and packaging of the cable tray. Table 1 Protection types and corresponding levels of environmental conditions for use of cable trays Protection category
Ordinary type
Wet and hot type
Medium corrosion resistance type
Strong corrosion resistance type
Approved by the Ministry of Machinery Industry on August 21, 1993
Protection type code
Standard Download Network (www.bzxzw.com)
Level of environmental conditions for use
3K5L, 3K6, 3K6L
3K5L/3B2 /3C2
3K5L/3B2/3C3
3K5L/3B2/3C4
1993-10-01 implementation
Protection category
Outdoor type
Outdoor medium corrosion protection type
Outdoor strong corrosion protection type
JB/T67431993
Continued Table 1
Protection type code
Note: The impact on mold is only specified for export products protected by coatings. 3.3 Environmental parameters for various levels of environmental conditions are shown in Tables 2 and 3. Table 2 Climate environment parameters of different climate environment levels Environmental parameters
Low relative turbidity
High relative humidity
Solar radiation
Condensation conditions
Precipitation conditions
mm/min
Icing conditions
Environmental parameters \
Sulfur dioxide
Hydrogen sulfide
Hydrogen oxide
Environmental parameters of chemically active substances of different corrosion levels Table 3
3C2, 4C2
Average value"
Maximum value"
3C3, 4 C3
Average value
Maximum value
Salt spray conditions"
Use environment conditions and other slow
4K2/4B1/4C2
4K2/4B1/4C3
4K2/4B1/4C4
3C4,4C4
Average value
Maximum value
Environmental parameters\
Hydrogen fluoride
tng/m3
Ammonia oxide 4,
3C2,4C2
Average value
JB/T 6743—1993
Continued Table 3
3C3, 4C3
Maximum value?
Average value
Maximum value
3C4, 4C4
Maximum value
Note: 1) When the concentration value of one or more chemical gases in the ambient air meets the values in this table, it belongs to this level; 2) The average value is the average of the long-term values, and the maximum value is the limit value or peak value that does not exceed 30 minutes per day. If it exceeds 30min, the grade should be increased:
3) Salt spray conditions are qualitatively specified and not used for grade division; 4) Equivalent to the value of dihydrogen oxide.
&Technical requirements
The thickness of various protective coatings (platings) shall comply with the provisions of Table 4. Table 4 Requirements for the thickness of various protective layers
Protective layer method
Bridge components
Protective layer thickness
Hot-dip galvanizing or zinc alloy
≥65(460g/m2)
≥54 (382g/m2)
Electro-galvanized
>M14,≥12;
M8~M12.≥9
≤M6,≥6
The uniformity, apparent quality and adhesion of the bond or coating shall meet the following requirements. 4.2
4.2.1Hot-dip zinc or zinc alloy:
Thermosetting powder electrostatic spraying
4.2.1.1The surface of hot-dip zinc or zinc alloy shall be uniform, without burrs, overburning, dust, scars and other defects. The number of missed plating points with a diameter of <2mm shall not exceed 3 points per workpiece; and there shall not be 2 missed plating points in any 100cm2 area. 4.2.1.2The uniformity of hot-dip zinc or zinc alloy layer shall not expose the metal substrate after 4 dippings according to the method specified in Appendix B of this standard. The coating thickness can also be measured by magnetic or other suitable instruments. 4.2.1.3 The adhesion of the hot-dip zinc or zinc alloy layer shall be tested according to the heavy manganese impact test method specified in Appendix C of this standard. The zinc or zinc alloy layer shall not be left.
4.2.2 Electroplated layer
The surface of the electroplated zinc layer shall be uniform, bright and free of bubbles. The thickness of the coating shall be measured by magnetic or other suitable instruments. The thickness of the thinnest layer on the plane shall not be less than 80% specified in Table 4, and shall not exceed 20% of the test points. Its fasteners shall not be affected by the coating. 4.2.3 CoatingWww.bzxZ.net
The surface of the powder coating or paint layer shall be uniform, flat and bright, without defects such as wrinkles and bubbles. The adhesion of the coating shall not be less than the second level specified in GB1720; the impact resistance shall not be less than 40kg·cm according to GB1732. 4.3 The electric bridge of different environmental protection types shall be subjected to artificial climate test according to the cycle specified in Table 5. The evaluation level of surface appearance quality after the test shall be as specified in Table 6.
Test item name
Alternating damp heat test\
Salt spray test
JB/T 67431993
5Artificial climate test items and periodic table for various protection types of cable trays5
Test cycle for each protection type
Test method standard number
GB2423.4Test Db
GB2423.17Test Ka
High concentration sulfur dioxide corrosion gas test*
Ultraviolet rays"
Condensation test
GB2423.33 Test Kch
Artificial air-cooled test method for plastic, polyester and rubber materials
Note: 1) The high temperature stage of the alternating damp heat test is 40±2°C, and the lower limit of the relative humidity in the cooling stage is 85%; 2) The concentration of sulfur dioxide corrosive gas is 17.5mg/L; 3) The ultraviolet light is 60°C for 8h and the condensation is 50°C for 4h. Only the cable tray with a protective layer of paint is tested. Table 6 Regulations for grading the appearance quality of protective layer
Hot-dip galvanized or electro-galvanized layer
The gloss is allowed to darken slightly, the color fades slightly, but the coating has no corrosion spots. The gloss is allowed to darken slightly, the color fades slightly, and the coating has individual corrosion spots (the area of corrosion spots is ≤15%)
The color has changed significantly, and there are a small number of corrosion spots in the coating (the area of flat corrosion spots is ≤50%). The bottom metal has no rust spots
The color has changed significantly, and the coating is severely corroded (the area of corrosion spots is >50%). The bottom metal (including punching holes and edge parts) has obvious rust spots. After artificial climate testing, the cable tray shall meet the following requirements. 4.4.1
The surface appearance of powder coating or oil coating is good, and the gloss and color have no obvious change. Outdoor
The coating surface is allowed to have slight color loss and slight gloss loss, but no defects such as bubbles. The coating surface has obvious color changes, but no defects such as bubbles, and no rust spots on the base metal
The coating surface has obvious color changes and bubbles or the base metal has obvious rust spots
After the wet heat test, the surface protection layer shall not be lower than the requirements of level 2 specified in Table 6. After the mist or chemical corrosive gas test, the surface protection layer shall not be lower than the requirements of level 3 specified in Table 6, and the base metal including the edges shall not have obvious rust spots.
4.4.2
When the indoor or outdoor anti-corrosion cable tray uses powder coating or paint layer as the protective layer, the gloss retention rate of the coating after the ultraviolet condensation test shall not be lower than 50% of the original gloss rate, and no bubbles shall be generated on the surface. 4.4.4 When the cable tray with powder coating or paint as protective layer is used outdoors at 4K2, i.e. the lowest temperature is -35℃, it is still necessary to conduct a 40℃ test according to the temperature gradient method in GB2423.1. After the test sample reaches a stable temperature for 4h, it is gradually restored to room temperature. Observe whether there are cracks on the coating surface.
4.4.5 For the export TH type cable tray with powder coating or paint as protective layer, after a 28d mildew test according to GB2423.16, the degree of mildew growth should not be greater than level 2.
Test method
Each test must be conducted on at least three test samples. Fasteners such as media bolts should use actual products. When conducting artificial climate tests, small-sized actual products such as pallets can be used, or simulated parts (size as shown in Figure 1) with the same materials, processes and protective layers as the actual products can be used.
JB/T67431993
Except for the hot-dip galvanizing process, the measurement of the protective layer thickness is measured in the actual product. Each sample is measured at least 5 points to obtain the average value. When the thickness of the electroplated zinc layer does not meet the requirements of Article 4.2.2 of this standard, the number of test points should be doubled for retesting, and the results of the retesting shall prevail. If it still does not meet the requirements of Article 4.2.2, it shall be considered unqualified. 150
Figure 1 Cable tray simulation test sample size
Unit mm
5.2 At the beginning of the test, dust and other impurities on the surface of the test sample should be removed first, and the appearance quality should be checked and the original value should be measured and recorded under the conditions of temperature of 15-35℃ and relative humidity of 45%-75%. 5.3 The test samples may not be pre-treated when undergoing artificial climate tests. They are placed in the test chamber (room) at the beginning of the test cycle and placed at 1535℃ and 45% to 75% relative humidity for more than 4 hours after the test cycle. When the samples undergoing salt spray or sulfur dioxide corrosion gas tests are taken out of the test chamber (room), the surface may be rinsed with tap water to remove residual salt or chemical media on the surface. 5.4 The treated test samples shall be inspected for appearance quality and their grades shall be carefully and strictly determined according to the provisions of Table 6 in Article 4.3. The gloss value of the samples undergoing UV/condensation tests shall be measured with gloss. During the test, the gloss value may be measured every 48 hours for reference and comparison. The samples undergoing low temperature tests shall be carefully inspected for cracks on the surface coating. 6 Inspection rules
All items shall be tested in parallel using samples of the same batch of materials and processes. Products of different protection types shall be tested separately. 6.1
6.2 Cable trays shall be tested in accordance with all items specified in this standard in one of the following situations. a,
Before materials and processes are finalized:
When changes in materials and processes affect the protective performance; during finalized production, regular inspections should be carried out, at least once every two years. 6.3 The factory inspection of cable trays shall be carried out in accordance with the provisions of Article 4.2 for the following tests. a.
Appearance quality;
Thickness of the surface protective layer;
Adhesion of the surface protective layer;
Impact resistance of the coating.
A1 Sample preparation
JB/T67431993
Hot-dip galvanizing adhesion test method (weight method) (supplement)
A1.1 Representative samples should be selected according to the material, material specifications, product shape, etc. A1.2 The sample is cut into 200mmX400mm and should be galvanized under the same process conditions as the product. A1.3 The adhesion is calculated using the three-point method. Cut off 50mm at each end of the galvanized sample, and then cut three sections from the middle and both ends of the sample to measure the adhesion and the average adhesion of the three sections of the sample, which is the average adhesion of the sample. A1.4 The test area of each section is 100cm2.
A2 Preparation of delamination solution
Dissolve 3.2g antimony trichloride or 2g antimony trioxide in 500mL concentrated hydrochloric acid with a specific gravity of 1.19, and dilute to 1L with distilled water. A3 Test method
The sample is cleaned of surface oil and dirt with organic solvents such as carbon tetrachloride and benzene, then rinsed with running water, wiped dry with a clean cloth, and then washed with ethanol. After sufficient drying, weigh (accurate to 1% of the estimated zinc layer weight of the sample section). The amount of delamination liquid is not less than 10mL per square centimeter of the sample surface. The weighed sample is placed in the delamination liquid (keeping the temperature of the delamination solution not higher than 38C) until the zinc coating is completely dissolved and the hydrogen bubbles are significantly reduced. Take out the sample, rinse it with running water, remove the surface attachments with a hard brush, and then immerse it in ethanol. After taking it out, quickly dry it; weigh it again with the same accuracy. After weighing, measure the surface area of the sample (accurate to 1%). A4 Calculation of adhesion
Where: A——Adhesion, g/m2;
G,—Weight of sample before delamination, g:
G2——Weight of sample after delamination, g
SSurface area of sample, mm.
Approximate thickness of zinc coating
Where:——Thickness of zinc coating,:
A-—Attachment, g/m2;
—Density of zinc coating, k/cm2, p is taken as 7. e
B1 Sample preparation
JB/T67431993
Hot-dip galvanizing layer uniformity test method (copper sulfate test) (supplement)
Representative samples should be selected according to the material, material specifications and product shape. B1.1
B1.2 After the sample is cut into appropriate size, it should be galvanized under the same process conditions as the product. B1.3 Cut a 10cm long sample from the sample for the copper sulfate test. If the sample is too large, it is allowed to be galvanized after appropriate cutting. The size of the steel plate sample is 10cm×10cm.
B1.4 Bolts and nuts, take the original for the copper sulfate test. B1.5 Use carbon tetrachloride, benzene, etc. to remove surface oil stains on the sample, rinse it with running water, wipe it dry with a clean cloth, and then immerse it in a 2% sulfuric acid solution (2mL sulfuric acid with a specific gravity of 1.84 is diluted with 98mL water). After 15s, rinse it with running water, wipe it dry with a clean cloth, and paint or paraffin on the exposed base metal parts at both ends of the sample.
Method for preparing copper sulfate solution
36g of chemically pure copper sulfate (CuSOg, 5H, 0) is placed in 100mL of distilled water, heated to dissolve, cooled to room temperature, and copper hydroxide or copper carbonate (1g per liter of sulfuric acid pot solution) is added. After stirring evenly, it is left to stand for more than 24 hours, and then the clear solution above is filtered or sucked out for use. The specific gravity of the solution should be 1.18 at 18°C, otherwise it should be adjusted with concentrated copper sulfate solution or distilled water. B3 Test preparation
B3.1 The copper sulfate solution should be contained in a container that does not react chemically with copper sulfate. The container should have an appropriate volume so that the copper sulfate solution can immerse the sample and keep the sample at a distance of not less than 25mm from the container wall. B3.2 The amount of copper sulfate solution is calculated as no less than 8mL per square centimeter of the test area. B4 Test method
Place the prepared sample in a copper sulfate solution at 18±2℃ and soak for 1 minute. Do not stir the solution or move the sample. Take out the sample immediately after 1 minute, rinse it with running water, and use a soft brush to remove the black precipitate, especially the precipitate in the pores and concave areas. Then wipe it dry with a clean cloth and immediately proceed to the next etching. Each prepared copper sulfate solution can be etched 15 times. B5 Determination of etching end point
After the above test, the sample reaches the etching end point when red metallic copper appears on the sample. The etching when metallic copper appears is not counted in the number of copper sulfate tests. B5.1
B5.2 Scrape off the attached metallic copper with a tool without a sharp edge. If there is still metallic zinc under the copper, it is not considered as the corrosion end point. B5.3 The following situations are not considered as the corrosion endpoint: When red copper appears within 25mm of the end of the specimen: a
When red copper appears at the corners of the specimen; When red copper appears at the scratched and abraded parts and around them after galvanizing. c.
CI hammer test device
JB/T6743—1993
Hot-dip galvanized layer adhesion hammer test method (supplement)
The hammer used for the test should be installed on a stable wooden test bench, and the test surface should be kept at the same height as the hammer base. The hammer test device is shown in Figure C1.
Test rules
The specimen should be placed horizontally, with the hammer head facing the center of the bench, and the hammer handle perpendicular to the base plane and then fall freely. Hit 5 points in parallel at intervals of 4mm. Check the surface state of the zinc layer. The hitting point is more than 10mm away from the end, and the hitting point shall not be hit twice repeatedly. 1×45°
Initial hole 10×25
1X45°
Figure C1 Hammer test device diagram
Note: ①The hammer head is made of 45# steel; weight 210g, hammer blade hardness (Shore) above 40. The hammer handle is made of oak; weight about 70g,
The base steel plate is 15mm thick, 250mm×250mm long and wide, and made of A3F.?
JB/T67431993
Classification of corrosion environment and selection of surface protection treatment methods for cable trays of different protection types
(reference)
For the classification of corrosion environment, please refer to Table D1; for the surface protection schemes of various protection types, please refer to the schemes in Table D2. Table D1
Reference basis
Operating conditions
Apparent phenomena
Ventilation conditions
Geographic conditions, including the degree of chemical corrosive
Concentration difference of corrosive substances
Humidity and temperature characteristics
Environmental conditions
Ordinary type
Wet and hot type
Medium corrosion type
Strong corrosion type
Light corrosion type
Huzhou Medium corrosion type
Strong corrosion type
Note: ×
Anti-light corrosion environment
Reference basis for the classification of corrosion environment
Anti-moderate corrosion environment
Due to the wind direction, chemical corrosion can sometimes be smelled| |tt||Smell of chemical substances
There is only general rust phenomenon in the building process and electrical facilities. The process and electrical facilities only need routine maintenance. Generally, trees grow normally
The ventilation conditions are normal
Indoors, there is no or far away from places with chemical corrosion
The relative humidity is high, but it lasts very long
Indicates applicable environment:
Electrogalvanizing
Anti-strong corrosion environment
Can often feel the stimulation of chemical substances,
but no protective equipment is required for normal process operation
The corrosion phenomenon of buildings, processes and electrical facilities is obvious , process and electrical facilities generally need annual overhaul; generally trees grow in places with good natural ventilation, a little far from the seashore, or places with chemical corrosive substances whose concentration is not the most severe, with high relative humidity, and the duration is not recommended for surface protection treatment methods. Protective layer category: spray powder, hot dip zinc coating, composite layer, which has strong irritation to the eyes or external respiratory tract, and sometimes protective equipment is required to carry out normal process operation. The corrosion of buildings, processes and electrical facilities is serious, and the equipment overhaul interval is relatively short; Generally, the survival rate of trees is low
, the ventilation conditions are poor
, the seaside or the places with high concentration of chemical corrosive substances
, the hot and humid areas or the relative humidity is extremely high for a long time
, the purification
, determined in accordance with the provisions of Article 4 of this standard
, 1) For powder coatings against medium and strong corrosion, chemical anti-corrosion powder coatings with an edge coverage of ≥30% must be selected; 2) When used in outdoor environments, powder or paint coatings must be selected according to the provisions of Article 4.3 Table 5 and Article 4.4.3 of this standard. 3) When the surface protection process of hot-dip zinc or zinc alloy is used in medium and strong corrosion conditions, the surface must be treated with galvanizing. 9
Additional instructions:
JB/T67431993
This standard is proposed and managed by Guangzhou Electric Science Research Institute of the Ministry of Machinery Industry. This standard was jointly drafted by Guangzhou Electric Science Research Institute, Jixi Cable Tray Factory, Panyu Cable Tray Factory and Heilongjiang Low Temperature Electromechanical Research Institute. The main drafters of this standard are Liang Xingcai, Gao Renzhi, Pan Huisheng, Sun Dianren, Liang Peiyun and Wang Dianxiang.?
JB/T67431993
Classification of corrosion environment and selection of surface protection treatment methods for cable trays of different protection types
(reference)
For the classification of corrosion environment, please refer to Table D1; for the surface protection schemes of various protection types, please refer to the schemes in Table D2. Table D1
Reference basis
Operating conditions
Apparent phenomena
Ventilation conditions
Geographic conditions, including the degree of chemical corrosive
Concentration difference of corrosive substances
Humidity and temperature characteristics
Environmental conditions
Ordinary type
Wet and hot type
Medium corrosion type
Strong corrosion type
Light corrosion type
Huzhou Medium corrosion type
Strong corrosion type
Note: ×
Anti-light corrosion environment
Reference basis for the classification of corrosion environment
Anti-moderate corrosion environment
Due to the wind direction, chemical corrosion can sometimes be smelled| |tt||Smell of chemical substances
There is only general rust phenomenon in the building process and electrical facilities. The process and electrical facilities only need routine maintenance. Generally, trees grow normally
The ventilation conditions are normal
Indoors, there is no or far away from places with chemical corrosion
The relative humidity is high, but it lasts very long
Indicates applicable environment:
Electrogalvanizing
Anti-strong corrosion environment
Can often feel the stimulation of chemical substances,
but no protective equipment is required for normal process operation
The corrosion phenomenon of buildings, processes and electrical facilities is obvious , process and electrical facilities generally need annual overhaul; generally trees grow in places with good natural ventilation, a little far from the seashore, or places with chemical corrosive substances whose concentration is not the most severe, with high relative humidity, and the duration is not recommended for surface protection treatment methods. Protective layer category: spray powder, hot dip zinc coating, composite layer, which has strong irritation to the eyes or external respiratory tract, and sometimes protective equipment is required to carry out normal process operation. The corrosion of buildings, processes and electrical facilities is serious, and the equipment overhaul interval is relatively short; Generally, the survival rate of trees is low
, the ventilation conditions are poor
, the seaside or the places with high concentration of chemical corrosive substances
, the hot and humid areas or the relative humidity is extremely high for a long time
, the purification
, determined in accordance with the provisions of Article 4 of this standard
, 1) For powder coatings against medium and strong corrosion, chemical anti-corrosion powder coatings with an edge coverage of ≥30% must be selected; 2) When used in outdoor environments, powder or paint coatings must be selected according to the provisions of Article 4.3 Table 5 and Article 4.4.3 of this standard. 3) When the surface protection process of hot-dip zinc or zinc alloy is used in medium and strong corrosion conditions, the surface must be treated with galvanizing. 9
Additional instructions:
JB/T67431993
This standard is proposed and managed by Guangzhou Electric Science Research Institute of the Ministry of Machinery Industry. This standard was jointly drafted by Guangzhou Electric Science Research Institute, Jixi Cable Tray Factory, Panyu Cable Tray Factory and Heilongjiang Low Temperature Electromechanical Research Institute. The main drafters of this standard are Liang Xingcai, Gao Renzhi, Pan Huisheng, Sun Dianren, Liang Peiyun and Wang Dianxiang.?
JB/T67431993
Classification of corrosion environment and selection of surface protection treatment methods for cable trays of different protection types
(reference)
For the classification of corrosion environment, please refer to Table D1; for the surface protection schemes of various protection types, please refer to the schemes in Table D2. Table D1
Reference basis
Operating conditions
Apparent phenomena
Ventilation conditions
Geographic conditions, including the degree of chemical corrosive
Concentration difference of corrosive substances
Humidity and temperature characteristics
Environmental conditions
Ordinary type
Wet and hot type
Medium corrosion type
Strong corrosion type
Light corrosion type
Huzhou Medium corrosion type
Strong corrosion type
Note: ×
Anti-light corrosion environment
Reference basis for the classification of corrosion environment
Anti-moderate corrosion environment
Due to the wind direction, chemical corrosion can sometimes be smelled| |tt||Smell of chemical substances
There is only general rust phenomenon in the building process and electrical facilities. The process and electrical facilities only need routine maintenance. Generally, trees grow normally
The ventilation conditions are normal
Indoors, there is no or far away from places with chemical corrosion
The relative humidity is high, but it lasts very long
Indicates applicable environment:
Electrogalvanizing
Anti-strong corrosion environment
Can often feel the stimulation of chemical substances,
but no protective equipment is required for normal process operation
The corrosion phenomenon of buildings, processes and electrical facilities is obvious , process and electrical facilities generally need annual overhaul; generally trees grow in places with good natural ventilation, a little far from the seashore, or places with chemical corrosive substances whose concentration is not the most severe, with high relative humidity, and the duration is not recommended for surface protection treatment methods. Protective layer category: spray powder, hot dip zinc coating, composite layer, which has strong irritation to the eyes or external respiratory tract, and sometimes protective equipment is required to carry out normal process operation. The corrosion of buildings, processes and electrical facilities is serious, and the equipment overhaul interval is relatively short; Generally, the survival rate of trees is low
, the ventilation conditions are poor
, the seaside or the places with high concentration of chemical corrosive substances
, the hot and humid areas or the relative humidity is extremely high for a long time
, the purification
, determined in accordance with the provisions of Article 4 of this standard
, 1) For powder coatings against medium and strong corrosion, chemical anti-corrosion powder coatings with an edge coverage of ≥30% must be selected; 2) When used in outdoor environments, powder or paint coatings must be selected according to the provisions of Article 4.3 Table 5 and Article 4.4.3 of this standard. 3) When the surface protection process of hot-dip zinc or zinc alloy is used in medium and strong corrosion conditions, the surface must be treated with galvanizing. 9
Additional instructions:
JB/T67431993
This standard is proposed and managed by Guangzhou Electric Science Research Institute of the Ministry of Machinery Industry. This standard was jointly drafted by Guangzhou Electric Science Research Institute, Jixi Cable Tray Factory, Panyu Cable Tray Factory and Heilongjiang Low Temperature Electromechanical Research Institute. The main drafters of this standard are Liang Xingcai, Gao Renzhi, Pan Huisheng, Sun Dianren, Liang Peiyun and Wang Dianxiang.
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