SY/T 0315-1997 Technical standard for fusion bonded epoxy powder coating on steel pipelines
Some standard content:
1 General Principles
Petroleum and Natural Gas Industry Standard of the People's Republic of China Steel Pipeline Fusion Epoxy Powder
External Coating Technical Standard
Approval Department: China National Petroleum Corporation Approval Date: 1997-12-28
Implementation Date: 1998-06-01
SY/T 0315—1997
1.0.1 This standard is formulated to ensure the anti-corrosion quality of the external coating of steel pipeline fusion epoxy powder (hereinafter referred to as epoxy powder), extend the service life of steel pipelines, and improve economic benefits. 1.0.2 This standard is applicable to the design, construction and acceptance of the external coating of steel pipelines using epoxy powder coating as the film-forming material. The coated pipe body can be used for buried pipelines or underwater pipeline facilities, with an operating temperature of -30 to 100°C. 1.0.3 In addition to complying with this standard, the design, construction and acceptance of the external coating of steel pipe epoxy powder shall also comply with the provisions of the relevant mandatory standards currently in force in the country.
1.0.4 The names and numbers of some referenced standards are as follows: GB/T1408-1989 Test method for power frequency electrical strength of solid insulating materials Test method for volume resistivity and surface resistivity of solid insulating materials GB/T 1410---1989
GB/T 2482—1986
Determination method for magnetic content of abrasive materials
GB/T 4472-—1984
, General rules for determination of density and relative density of chemical products GB/T 6554—1986
Test method for electrical insulation coating powder
2 Basic provisions
2.0.1 When ordering anti-corrosion pipes, the buyer shall provide the anti-corrosion factory with the following information: 1 Quantity, outer diameter, wall thickness and length of steel pipes, standard or specification of steel pipes;
Thickness of coating;
Length of reserved section at pipe end;
Number of times of re-coating test.
If necessary, the ordering requirements shall also include the following: additional surface pretreatment;
Factory inspection by the buyer;
Additional test pieces;
Additional markings;
Shipping requirements,
Storage requirements;
Additional laboratory coating test pieces;
Other special requirements.
The following items must be agreed upon by both the buyer and the anti-corrosion plant: 2.0.3
How to deal with steel pipes with defects that cannot be removed during normal production; buyer inspection sites outside the coating construction site; alternative methods for measuring the anchor mark depth on the outer surface of steel pipes; how to deal with steel pipes with surface defects; bzxz.net
Repair methods used when the leak exceeds the predetermined limit; length of pipe section test pieces:
Additional repeated test plans;
Other optional repair materials,
Recoating of coated steel pipes.
3 Epoxy powder outer coating structure
Epoxy powder outer coating is a one-time film-forming structure SY/T 0315—1997
The thickness of epoxy powder outer coating for steel pipelines shall comply with the design requirements of the pipeline project. If there is no design requirement, it can be selected according to the coating use conditions and the provisions of Table 3.0.2.
Table 3.0.2 Thickness of epoxy powder coating on buried steel pipes No.
4 Material
4.1 Steel pipe
Coating level
Ordinary level
Reinforced level
Minimum thickness (μm)
4.1.1 The steel pipe to be coated shall comply with the provisions of the current national standards or the specifications and characteristics specified by the buyer. Reference thickness (μm)
300~400
400~500
4.1.2 The anti-corrosion manufacturer shall inspect the appearance and dimensional deviation of each steel pipe, and the appearance and dimensional deviation shall comply with the provisions of the current national steel pipe standards.
4.2 Epoxy powder
4.2.1 The epoxy powder coating manufacturer shall provide relevant technical information such as product manual, factory inspection certificate and quality certificate. 4.2.2 Epoxy powder coatings should be packaged in good condition. The anti-corrosion plant should store epoxy powder coatings in accordance with the temperature and humidity conditions recommended by the epoxy powder manufacturer. When epoxy powder is delivered, the name of the manufacturer, the name, model, batch number, production date, expiration date, etc. of the coating should be clearly marked on its outer packaging.
4.2.3 The performance of epoxy powder coatings should comply with the requirements of Table 4.2.3. Table 4.2.3 Properties of epoxy powder
Test items
Curing time (min)
Gel time (s)
Thermal properties
Non-volatile matter content (%)
180℃
230℃
180℃
230℃
Quality indicators
Uniform color, no agglomeration
Conform to the characteristics given by the epoxy powder manufacturer
Test method
Appendix A
GB/T 6554--1986
Appendix B
GB/T 6554—1986
SY/T 0315---1997
Test items
Particle size distribution (%)
Density (g/cm2)
Magnetic content (%)
Quality index
150μm sieve powder ≤3.0
250μm sieve powder ≤0.2
1. 3~1. 5
Test method
GB/T 6554-1986
GB/T4472—1984
GB/T 2482--1986
4.2.4 Each brand (type) of epoxy powder coating should be inspected according to the items in Table 4.2.3 before use. It can only be used when its performance meets the acceptance quality requirements.
5 External coating application
5.0.1 Before coating, the coating shall be tested for 24h cathodic stripping, 3° bending resistance, 1.5J impact resistance and adhesion through the coating test piece, and the test results shall meet the requirements of Table 5.0.2. When one or more of the three items of the manufacturer, coating formula and production location change, the coating shall be retested in accordance with the provisions of Article 5.0.2 of this standard. 5.0.2 The preparation and testing of laboratory coating test pieces shall comply with the following provisions: 1 The test piece substrate shall be low carbon steel, and its dimensions shall meet the requirements of the various tests in the appendix of this standard. 2 The surface of the test piece shall be spray cleaned, and its rust removal quality shall meet the requirements of Sa2< in "Rust Grade and Rust Removal Grade of Steel Surface Before Coating" GB/T8923-1988. The anchor mark depth on the surface shall be within the range of 40 to 100μm and meet the requirements recommended by epoxy powder manufacturers.
3 The curing temperature of the coating shall be in accordance with the recommended value of the epoxy powder manufacturer and shall not exceed 275℃. 4 The coating thickness on the test piece shall be 350μm±50μm; 5 The tests on the laboratory coated test pieces shall comply with the provisions of Table 5.0.2. Table 5.0.2 Coating quality requirements for laboratory test pieces Test items
24 or 48h cathodic peeling (mm)
28d cathodic peeling (mm)
Chemical corrosion resistance
Cross-section porosity (grade)
Adhesive surface porosity (grade)
3° bending resistance
1.5J impact resistance
Thermal properties
Electrical strength (MV/m)
Volume resistivity (α·m)
Adhesion (grade)
Abrasion resistance (falling sand method) (L/ μm)
Quality index
Smooth, uniform color, no bubbles, cracks and shrinkage holes, slight orange peel pattern is allowed
No cracks
No pinholes
Conform to the characteristics given by the epoxy powder manufacturer
≥1×103
Test method
Appendix C
Appendix C
Appendix D
Appendix E
Appendix E
Appendix F
Appendix G
Appendix B
GB/T 1408—1989
GB/T 1410--1989
Appendix H
5.0.3 Surface pretreatment shall meet the following requirements: SY/T 0315-1997
1 Before coating the outer surface of the steel pipe, the oil, grease and any other impurities on the outer surface of the steel pipe must be removed by appropriate methods. 2 Before spraying (blasting) rust removal, the steel pipe should be preheated to remove moisture, and the preheating temperature is 4060℃. 3 The spraying (blasting) rust removal on the outer surface of the steel pipe should reach the Sa2K level specified in GB/T8923-1988. The anchor pattern depth on the steel pipe surface should be within the range of 40~100μm and meet the recommended requirements of the epoxy powder manufacturer. 4 After spraying (blasting) rust removal, the rust powder and dust remaining on the outer surface of the steel pipe should be cleaned. Spraying should be carried out within 8h after the steel pipe surface is pretreated. When rust or surface contamination occurs, the surface pretreatment must be repeated. 5 If the buyer has other special requirements, the surface pretreatment should be carried out according to the buyer's requirements before coating. 5.0.4 The coating and curing temperature and coating thickness shall comply with the following provisions: 1 The coating temperature of the outer surface of the steel pipe must comply with the temperature range required by the epoxy powder coating, but the maximum shall not exceed 275°C. 2 When applying the outer coating, the curing temperature and curing time shall comply with the requirements of the epoxy powder coating. 3 The maximum thickness of the coating shall be determined by the buyer, and the minimum thickness shall comply with the requirements of Table 3.0.2 of this standard. 5.0.5 The length of the reserved section at both ends of the steel pipe should be 50mm±5mm, and there shall be no coating on the surface of the reserved section. If the buyer has requirements, it can be stipulated by itself.
6 Quality Inspection
6.1 Inspection before Coating
6.1.1 Before coating, each batch of epoxy powder coating shall be sampled at least once, and the gel time test shall be carried out according to the method in "Test Methods for Electrical Insulation Coating Powder" GB/T6554-1986, and its indicators shall comply with the requirements of Table 4.2.3 of this standard. 6.2 Quality inspection of coating process
6.2.1 After surface pretreatment, each steel pipe shall be visually inspected. Surface defects that may cause coating leaks shall be polished off, and the wall thickness after polishing shall not be less than the specified value. Defective steel pipes shall be removed or trimmed. 6.2.2 Appropriate methods shall be used to detect the rust removal quality and anchor depth of the steel pipe surface after pretreatment. The surface rust removal level shall reach the Sa2 level specified in GB/T8923--1988, and the anchor depth of the steel pipe surface shall be within the range of 40~~100μm. In continuous production, the surface pretreatment quality of the steel pipe shall be tested at least once every 8 hours. 6.2.3 The preheating temperature of the steel pipe surface before coating must be controlled within the range recommended by the epoxy powder manufacturer, and the temperature value shall be recorded at least once every hour.
6.2.4 The temperature of the steel pipe after coating and before quenching shall be controlled, and measured and recorded at least once every hour from the start of production. 6.2.5 The entire coating of each steel pipe shall be tested for leaks using an electric spark leak detector when the coating temperature is below 100°C, with a detection voltage of 5V/μm.
6.3 Factory inspection of externally coated steel pipes
6.3.1 The factory inspection of epoxy powder externally coated steel pipes shall include the inspection of coating appearance quality, coating thickness and leaks, and each inspection shall be carried out in accordance with the following requirements:
1 The appearance quality of the external coating shall be inspected pipe by pipe. The appearance shall be flat, uniform in color, free of bubbles, cracks and shrinkage cavities, and slight orange peel patterns are allowed.
2 Using a coating thickness gauge, randomly select three positions along the length of each steel pipe, measure the thickness of the anti-corrosion layer at any four points evenly distributed in the circumferential direction of each position and record the results. The results shall meet the requirements of Article 3.0.2 of this standard. If the coating thickness requirements are not met, recoating shall be carried out in accordance with the provisions of Article 7.0.2 of this standard.
3 Use an electric spark leak detector to check the outer coating of the steel pipe one by one. When the number of leaks is within the following range, repairs can be carried out in accordance with the provisions of Article 7.0.1 of this standard: When the outer diameter of the steel pipe is less than 325mm, the average number of leaks per meter of pipe length shall not exceed 1.0; when the outer diameter of the steel pipe is equal to or greater than 325mm, the average number of leaks per square meter of surface area shall not exceed 0.7. When the number of leaks exceeds the above number, or the area of individual leaks is greater than or equal to 250cm2, the steel pipe shall be treated in accordance with the requirements of Article 7.0.2 or Article 7.0.3 of this standard after consultation with the buyer. 751
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6.4 Type inspection of externally coated steel pipes
6.4.1 For each batch of epoxy powder coated steel pipes with a continuous production length of 10 km or more, after production is put into operation, pipe section test pieces with a length of about 500 mm should be cut at 500 m, 5000 m and 10000 m to test the various indicators in Table 6.4.1. After that, pipe section test pieces should be cut every 10000 m. For each batch of epoxy powder coated steel pipes with a continuous production length of less than 10 km, the sampling frequency can be determined by negotiation between the anti-magic factory and the buyer. Table 6.4.1 Type inspection items and acceptance indexes of external coated steel pipes Test items
24h or 48h cathodic peeling (mm)
2.5° bending resistance
1.5J impact resistance
Adhesion (grade)
Acceptance index
No crack
No pinhole
Test method
Appendix C
Appendix F
Appendix G
Appendix H
6.4.2 If the test results do not meet the requirements of Table 6.4.1 of this standard, the coating process parameters should be adjusted immediately. At the same time, two additional test pieces are added between the unqualified test pipe section and the previous qualified test pipe section for retesting. When both retested test pieces are qualified, the steel pipes coated in this interval can pass the acceptance. If one of the two re-tested pieces fails, all products between the previous qualified test and the failed test pipe section shall be deemed unqualified. Subsequent production shall be conducted by sampling test pipe sections for testing in accordance with the requirements of Article 6.4.1 of this standard.
6.4.3 Unqualified products shall be re-coated in accordance with the requirements of Article 7.0.3 of this standard. 7 Repair, recoating and re-coating of coatings
7.0.1 When using local repair methods to repair coating defects, the following requirements shall be met: 1 All rust, scales, dirt and other impurities and loose coatings on the defective parts must be removed; 2 The defective parts shall be polished to a rough surface;
3 Use a dry cloth and brush to remove dust; 4 For defective parts with a diameter less than or equal to 25mm, local repair shall be carried out using hot melt repair rods recommended by the epoxy powder manufacturer, two-component epoxy resin paint or equivalent materials agreed by the buyer; 5 For defective parts with a diameter greater than 25mm and an area less than 250cm2, local repair shall be carried out using two-component epoxy resin paint recommended by the epoxy powder manufacturer or equivalent materials agreed by the buyer; 6 The repair material shall be used in accordance with the method recommended by the manufacturer 7 The thickness of the repaired coating shall meet the requirements of Article 6.3.1 of this standard. 7.0.2 If the thickness of the steel pipe coating does not meet the requirements of Article 3.0.2 of this standard, recoating shall be carried out (applying another layer on the first coating). When recoating, blistering, peeling and damage to the original coating must be avoided. After recoating, the quality inspection requirements of Article 6.3.1 of this standard shall be met.
7.0.3 If the outer coated steel pipe fails the type inspection, it must be recoated. If the number of coating leaks or the area of individual leaks exceeds the provisions of Articles 6 and 3.1 of this standard, recoating or re-coating shall be carried out after consultation with the buyer. When recoating, the surface of the steel pipe shall be heated to no more than 275°C to soften the coating, then the coating shall be scraped off and then sprayed (blasted). All coatings must be removed before recoating. Recoating shall be carried out in accordance with the coating requirements of Chapter 5 of this standard, and after recoating, quality inspection shall be carried out in accordance with the quality requirements of Chapter 6 of this standard. After recoating, the coating quality shall meet the requirements of Article 7.0.2 of this standard. 8 Marking, shipment and storage of finished pipes
8.1 Marking
8.1.1 The outer coated steel pipes that have passed the quality inspection shall be marked on their outer wall 1m away from the pipe end, indicating the steel pipe specifications, materials, grades, 752
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manufacturer name, implementation standards; type, grade, anti-corrosion pipe number, inspector code, coating factory name, production date, implementation standards, etc. of the outer coating, and provide the user with a factory certificate. 8.2 Shipping
Finished pipes should be lifted and transported gently to prevent impact deformation and mechanical damage. 8.2.1
8.2.2 During shipment, long steel pipes should be prevented from being bent too much to damage the outer coating. 8.2.3 If the steel pipe is damaged during operation, it should be handled in accordance with the technical requirements or standards of the steel pipe used. 8.2.4 If the coating is damaged during operation, it should be handled in accordance with the requirements of Chapter 7 of this standard. 8.2.5 Each finished pipe after coating should be covered with an isolation gasket. The size and position of the gasket should be based on the principle that the protected coating will not be damaged during stacking.
8.3.1 The anti-corrosion plant shall provide detailed instructions for the stacking site and storage facilities and methods according to the requirements of the buyer. 8.3.2 Finished pipes shall be stacked separately according to coating type and steel pipe specifications, and shall be arranged neatly and clearly marked. Steel pipes that fail the coating inspection shall not be mixed with finished pipes. When stacking outdoors, the site shall set up pipe supports such as wooden blocks and earth platforms, the height of which shall be 150mm above the natural ground and the distance between pipe supports shall be 4m. The number of stacking layers of anti-corrosion pipes shall comply with the requirements of Table 8.3.2. Table 8.3.2 Number of stacking layers of finished pipes
Pipe diameter d
Maximum number of stacking layers
200≤d300
300d<400
8.3.3 The stacking location of finished pipes shall be well ventilated to avoid sunlight and rain. 9 Safety, sanitation and environmental protection of coating production 400≤<500
500≤d<600
d≥600
9.0.1 The safety and environmental protection of coating production shall comply with the requirements of the current national standards "Safety Regulations for Coating Operations - Safety of Pre-painting Process" GB7692 and "Safety Regulations for Coating Operations - Ventilation and Purification of Pre-painting Process" GB7693. 9.0.2 During the rust removal and spraying production of steel pipes, the noise generated by various equipment shall comply with the relevant provisions of the current national standard "Design Specifications for Noise Control in Industrial Enterprises" GBJB7. 9.0.3 The dust content in the air of rust removal and spraying workshops shall not exceed the provisions of "Design Hygiene Standards for Industrial Enterprises" TJ36--1979. 9.0.4 The rotating and moving parts of all mechanical facilities in rust removal and spraying operations shall be equipped with safety protection facilities such as protective covers. 9.0.5 The electrical equipment in the epoxy powder spraying area shall comply with the national safety regulations on electrical equipment in explosion-hazardous places. The electrical facilities shall be explosion-proof as a whole, and the operating part shall be equipped with an electric shock protector. 10 Patching, trenching and backfilling
10.1 On-site patching and quality inspection
10.1.1 On-site patching should be thermally sprayed with the same epoxy powder coating as the pipe body. Spraying must be carried out before the water pressure test to avoid the failure to heat to the curing temperature required by the epoxy powder due to water in the steel pipe. 10.1.2 The patching area on the surface of the steel pipe must be sprayed for rust removal before spraying, and its surface quality should reach the Sa 2% level required by GB/T8923-1988. There should be no oil stains on the treated surface. 10.1.3 After spraying for rust removal, the dust and moisture at the patching must be removed, and the sharp points formed by splashing during welding must be leveled, and the coating within a width of 15mm at the overlap of the patching at the pipe end must be roughened. 10.1.4 The process parameters of the patching spraying shall be determined according to the following requirements: 753
SY/T 0315—1997
1 Before the patching construction begins, the patching test spraying shall be carried out on the test pipe section with the proposed spraying process until the coating quality meets the requirements of Chapter 6 of this standard.
For patching construction of pipes with a diameter of 273mm and above, a short pipe with the same specification as the construction pipe diameter shall be used as the spraying test pipe section. The size of the processed test piece shall meet the requirements of Table 10.1.4. Table 10.1.4 Specifications of test pipe sections
Adhesion
Bending resistance
Impact resistance
Cathode stripping
Test piece size
100mm (axial) × 100mm (circumferential) × steel pipe wall thickness 300mm (axial) × 30mm (circumferential) × steel pipe wall thickness 350mm (axial) × 170mm (circumferential) × steel pipe wall thickness 150mm (axial) × 150mm (circumferential) × steel pipe wall thickness For the patching construction of pipelines with a diameter of 219mm or less, a short pipe with a diameter of 273mm is used as the spraying test pipe section, and the test pieces of the above specifications are processed, but the thickness should be the same as that of the construction pipeline. The sample preparation method of the test pieces can also be determined by negotiation between the construction and pipeline user departments. 2 For the first patching construction of each day, the adhesion test should be carried out on site after spraying. The method is: after spraying, wait for the temperature of the pipe body to drop to the ambient temperature. Use the tip of the knife to scratch two parallel lines 10 mm apart on the coating along the axis of the steel pipe, and then scratch two parallel lines 10 mm apart and intersecting with the first two lines at an angle of 30° to form a parallelogram. It is required that each scratch line must penetrate the coating. Then, insert the tip of the knife under the coating at each inner angle of the parallelogram and apply horizontal thrust. If the coating peels off in flakes, the spraying parameters should be adjusted until the coating peels off in a crumbly state.
10.1.5 Use an induction heater to heat the pipe body at the patching site to the specified temperature, with an allowable deviation of ±5°C, and then spray. It is required that the spraying thickness is the same as the average thickness of the pipe body coating, and the overlap with the pipe body coating is not less than 25mm. 10.1.6 After patching, the appearance, thickness and leakage point of each pass should be inspected and recorded. 1 Appearance quality: Visually, the coating surface should be flat and smooth, and no obvious flow should be observed. 2 Thickness detection: Use a coating thickness gauge to measure the thickness of the patch area on both sides of the weld, including the upper, lower, left and right positions, and a total of 8 points. The minimum thickness shall not be less than the minimum thickness of the pipe body coating. If there is a small area with insufficient thickness, it can be repaired with paint after roughening. If the area of insufficient thickness exceeds 1/3 of the surface area of the patch area of the steel pipe, it should be re-sprayed. 3 Leakage point detection: Use an electric spark leak detector to detect the coating in the patch area with a DC voltage of 5V/um. If there is a leak, it should be handled in accordance with the requirements of Chapter 7 of this standard.
10.2 Trenching and backfilling
10.2.1 After all the patching is accepted, before the pipeline is trenched, the entire line must be re-tested in accordance with the relevant provisions of the "Construction and Acceptance Specifications for Long-distance Pipeline Line Projects" SYJ4001. If damaged areas are found, they should be handled in accordance with the requirements of Chapter 7 of this standard, and backfilling can only be carried out after passing the requirements. 10.2.2 Backfilling should be carried out in accordance with the relevant requirements of the current standard SYJ4001. 10.2.3 After backfilling, the ground audio leak detector should be used to conduct full-line inspection, and leaks must be repaired if found. 11 Handover materials
11.0.1 Quality certificate, certificate of conformity and re-inspection report of relevant test items of epoxy powder coating. 11.0.2 Quality certificate, certificate of conformity and re-inspection report of relevant test items of two-component liquid epoxy coating used for repair. 11.0.3 Quality inspection report of epoxy powder outer coating during production and quality inspection report of steel pipe outer coating. 11.0.4 Test report.
11.0.5 Production quality certificate of outer coating, including: project name, project number, coating name and model, coating quality index, technical person in charge, quality person in charge, etc.
11.0.6 Coating inspection data before installation.
11.0.7 Patching record and inspection data.
11.0.8 Coating inspection data before backfilling.
11.0.9 Ground audio leakage detection and repair, recoating and repainting data. Other technical data required by the user.
Appendix A
Test for curing time of epoxy powder
The equipment required for this test shall meet the following requirements: A. 0. 1
Electric heating plate, temperature accuracy is ± 3°C;
Metal plate, size is 150mm×150mm×25mm; 2
Mold release agent (glycerol), which is required to withstand high temperature of 300°C without sticking to epoxy powder; 4
Contact thermometer;
Timer;
6 Drawing plate (shape see Figure A.0.1);
Notch (25±1) mm×about 0.9 mm
Figure A.0.1 Drawing plate
Tweezers (small pliers);
8 Scraper,
9 Universal knife;
10 Differential scanning calorimeter (DSC).
A.0.2 The test steps shall comply with the following provisions: 1 Spray two layers of release agent on the upper surface of the metal plate. 2 Heat the metal plate and maintain the temperature at 230℃±3℃ or 180℃±3℃. SY/T 0315-1997
3 Use a drawing plate to quickly spread the epoxy powder on the metal plate and apply it into a thin film with a film thickness of 300-400μm; when the powder on the metal plate begins to melt, immediately start the timer to start timing. 4 Before the coating is completely gelled, use a general knife or scraper to divide the coating into 10 strips, as shown in Figure A.0.2. Layer
Divide the coating with a knife
A rat board
Scribing the coating flat plate
Figure A.0.2
SY/T 0315-1997
5After 30s±3s, pick up the first coating strip with tweezers and immediately quench it in cold water. 6Repeat the operation in the above paragraph every 30s±3s. Note that the strips should be removed, quenched and placed in order from top to bottom.
7Use a differential scanning calorimeter (DSC) to measure △T (change in glass transition temperature) or curing percentage according to the requirements of Appendix B of this standard.
8Draw a curve of time versus △T or time versus curing percentage according to the regulations of the powder manufacturer. A.0.3 The test report shall include the following: 1 The time corresponding to AT. being 2°C or the time S corresponding to 99% curing percentage; 2 The test date.
Appendix B
Test for thermal properties of epoxy powder and its coating B.0.1 This test is used to determine the glass transition temperature (T.) and reaction heat (AH) of epoxy powder and coating and the curing percentage (C) of coating.
B.0.2 The equipment required for this test shall comply with the following provisions: 1 Differential scanning calorimeter (DSC) with refrigeration equipment, 2 Analytical balance, accurate to 0.1mg;
3 Sample sealer;
4 Aluminum sample III with cover.
B.0.3 The test steps shall comply with the following provisions: 1 Take 10mg±1mg of epoxy powder or coating as a sample, put it into the pre-weighed sample blood, cover the sample with a lid to seal it and weigh it, the mass of the sample shall be accurate to 0.1mg.
2 Place the sample and reference in the dry inert gas protection measuring cell of the differential scanning calorimeter. 3 For the epoxy powder sample, complete its thermal scan according to the following operating procedures: 1) Heat the sample at a rate of 20℃/min from 25℃±5℃ to 70℃±5℃, and then cool the sample to 25℃±5℃;
2) Heat the same sample at a rate of 20℃/min from 25℃±5℃ to 285℃±10℃, and then cool the sample to 25℃±5℃:
3) Heat the sample at a rate of 20℃/min from 25℃±5℃ to 150℃±10℃; 4: For the coating sample , complete its thermal scan according to the following operating procedures: 1) Heat the sample at a rate of 20℃/min, from 25℃±5℃ to 110℃±5℃, keep it at 110℃ for 1.5min, and then cool the sample to 25℃±5℃;
2) Heat the same sample at a rate of 20℃/min, from 25℃±5℃ to 285℃±10℃, and then cool the sample to 25℃±5℃;
3) Heat the sample at a rate of 20℃/min, from 25℃±5℃ to 150℃±10℃. B.0.4 The test results should be calculated according to the following requirements: 1 Corresponding to each thermal scan line obtained in 2), 3) of B.0.3, paragraph 3 and 2), 3) of B.0.3, paragraph 4, determine its corresponding T. Value, which is at the intersection of the extrapolated baseline at the low temperature end and the tangent line at the turning point of the curve. In addition, the corresponding reaction exotherms △H and △H, (see Figure B.0.4-1 and Figure B.0.4-2) must be determined. 756
Excitation (℃)
Operation process
Operation process
Figure B.0.4-1 Thermal scan of epoxy powder
2For coatings, use formula (B.0.4-1) to calculate the change in T. value. ATg — Tg4 — T3
Where: △TT. Change in value (℃);
Temperature (℃)
SY/T0315—1997
Operation process
Operation process
Figure B.0.4-2 Thermal scan of coating
(B.0.4-1)
T obtained by thermal scanning in 3) of Section 4 of B.0.3. Value (℃), Tx4
T obtained by thermal scanning in 2) of item 4 of B.0.3. Value (℃). 3 For coatings, calculate the cure percentage using formula (B.0.4-2). AH-AHL ×100
Wherein:
Cure percentage (%),
Reaction exotherm obtained by thermal scanning in 2) of item 3 of B.0.3 (J/g); △H,--Reaction exotherm obtained by thermal scanning in 2) of item 4 of B.0.3 (J/g). B.0.5 The test report shall include the following:
1 Model of differential scanning calorimeter,
2 For epoxy powder, report T, Tz and AH values, 3 For coatings, report T3, T, △H and C values; 4 Test date.
Appendix C
Cathode residual resistance test of coating
C.0.1 The equipment required for this test shall comply with the following provisions: adjustable DC regulated power supply;
2 hot plate or oven, temperature accuracy is ±3℃;3 shallow steel plate containing quartz sand;
calomel electrode,
platinum wire or carbon electrode;
6 plastic round cylinder with inner diameter of 75mm±3mm;
73% NaCI solution;
8 general-purpose knife.
(B. 0. 4-2)
SY/T 0315--1997
C.0.2 The size of the laboratory coating specimen is about 100mm×100mm×6mm. The size of the pipe section specimen is about 100mm×100mm×pipe wall thickness. The number of specimens in each group is 2.
C.0.3 Test steps
1 This test should use a test piece that has been confirmed to have no leaks. The minimum leak detection voltage of the spark leak detector should be 1800V. 2 Drill a blind hole with a diameter of 3.2mm in the center of the test piece, penetrate the coating, and expose the steel substrate. 3 Align the center of the plastic cylinder with the blind hole and place it on the test piece, and seal it with sealant. There should be no water leakage. 4 Inject at least 300 mL of NaCl solution into the cylinder and mark the liquid level on the cylinder. Insert the electrode into the solution and connect it to the positive pole of the DC power supply, and then connect the test piece with the exposed blind hole to the negative pole. 5 Apply voltage to the test piece (apply voltage to the calomel reference electrode) under one or more of the following test conditions, keeping the temperature constant: 1) 1.5 V, 20℃±3℃, 28 d;
2) 1.5 V, 65℃±3℃, 48 h;
3) 3.5V, 65℃±3℃, 24 h,
During the test, add distilled water as needed to maintain the liquid level. 6 After the above test cycle, dismantle the electrolytic cell, remove the test piece, and cool it to 20℃±3℃ in air. Within 1 hour from the beginning of removing the power supply, test the cathodic disbonding resistance of the test piece. 7 Use a knife to draw radial lines with the blind hole as the center, as shown in Figure C.0.3. The line should penetrate the coating to the substrate and extend at least 20mm from the blind hole.
8 Use the tip of a knife to insert under the coating from the blind hole, and pry and peel the coating along the ray direction with a horizontal force until the coating shows obvious anti-peeling performance. 9 Starting from the center of the blind hole, measure each peeling distance and calculate the average value, which is the cathodic peeling distance of the specimen.
C.0.4 The arithmetic average of the cathodic peeling values of the two parallel test specimens is used as the cathodic peeling value of the group of specimens.
C.0.5. The test report should include the following: 1 Average peeling value;
2 Test date.
Appendix D
Chemical corrosion resistance test of coating
D.0.1 The immersion medium required for this test should comply with the provisions of Table D.0.1. Test media
Table D. 0. 1i
Dilute hydrochloric acid
10% sodium chloride plus diluted sulfuric acid
10% sodium chloride aqueous solution
Figure C.0.3 Radiation through the test piece
Coating
Distilled water
5% sodium hydroxide aqueous solution
Equal mass of saturated aqueous solution of magnesium carbonate and calcium carbonate pH value
D.0.2 Laboratory coating test piece size is about 200mm×25mm×6mm, all edges should be covered, and the base should not be exposed. At least 3 test pieces are immersed in each medium.
D.0.3 The test steps should comply with the following provisions: 758
SY/T 0315-—1997
1 Place the test piece vertically in the immersion container and add enough medium to submerge half of the length of the test piece. 2 Cover the container and keep the temperature at 20℃±3℃ for 90 days. If the liquid level drops, add appropriate amount of distilled water.
3 After the test cycle, take out the test piece and observe whether the coating has discoloration, bulging, softening, blistering, cracking, peeling, reduced adhesion, etc.
D.0.4 The test report should include the following: 1 The condition of the coating after 90 days of immersion in various media; 2 The test date.
Appendix E
Determination of the porosity of the coating
The equipment required for this test should meet the following requirements: 1
Stereo microscope;
Bench vice or special bending machine;
3Dry ice or freezer;
Universal knife.
E.0.2 The size of the laboratory coating specimen is about 200mm×25mm×6mm; the size of the pipe section specimen is about 200mm×25mm×pipe wall thickness, of which 200mm is the axial size of the pipe section. Each group of specimens consists of 3 pieces. E.0.3 The test steps shall comply with the following provisions: Cool the test piece to below -30℃ and bend it to about 180° on a bench vise or a special bending machine. 2 Pry off a piece of coating from the bent test piece and observe the porosity of the coating at 40 times magnification. 3 Evaluate the porosity grade of the test piece according to the grade chart shown in Figure E.0.3-1 and Figure E.0.3-2. E.0.4 The test results with the lowest grade among the three test pieces represent the coating cross-sectional porosity grade and coating bonding surface porosity grade of the group of test pieces.
E.0.5 The test report shall include the following contents: 1 Cross-sectional porosity grade;
2 Bonding surface porosity grade;
3 Test date.
890082880
Figure E. 0. 3-1
Porosity grade of coating cross section
980888
Figure E.0.3-2Porosity grade of coating bonding surface759
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