Standard test method for cathodic disbonding of pipeline coatings subjected to elevated temperatures
other information
drafter:Hou Yu, Feng Shaoguang, Liu Lingli, Li Jike, Wang Dezeng, Li Rongguang, Zhao Guoxing, Lin Rongfang, Li Guizhi, Jin Hui, Gao Yang, Zhang Jingyuan, Zhang Guozhen
Drafting unit:China Petroleum Pipeline Technology Research Center, China Petroleum Pipeline College, Zhejiang Yonggu Weihua Coatings Co., Ltd., China Industrial Anticorrosion Technology Association, Qingdao Dacang Pipeline Anticorrosion and Insulation Equipment Co
Focal point unit:National Anti-corrosion Standardization Technical Committee (SAC/TC381)
Proposing unit:China Petroleum and Chemical Industry Federation
Publishing department:General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Standardization Administration of China
Some standard content:
ICS 25.220.99
National Standard of the People's Republic of China
GB/T 314052015
Staatiard test method for cathocile disbonding of pipeline coatings subjecteci tc elevatec temperatures2015-05-15Issued
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of ChinaStandardization Administration of the People's Republic of China
2015-10-01Implementation
This standard is compiled in accordance with the general principles drawn up in CB/T 1.1-2009. This standard is proposed by China Petroleum and Chemical Industry Federation and is under the jurisdiction of the National Technical Committee for Anti-Corrosion Standardization (SAC/T381). GB/T31405—2015
The drafting organizations of this standard are: China Petroleum Pipeline Technology Research Center, Ningyu Petroleum Pipeline College, Zhejiang Yonggu Weihua Paint Co., Ltd., China Industrial Anticorrosion Technology Association, Qingdao Dacang Pipeline Anticorrosion Protection Equipment Co., Ltd. The main drafters of this standard are: Hou Yu, Feng Shaoguang, Liu Lengli, Li Jike, Sandedi, Li Rongguang, Zhao Guoken, Lin Rongfang, Li Nanzhi, Jin Hui, Gao Ti, Zhang Jingyuan and Zhang Guozhen.
1 Scope
Test method for high temperature cathodic stripping of pipeline corrosion resistant coating This standard specifies the accelerated test method for evaluating the high temperature cathodic stripping performance of pipeline external anti-corrosion coating GB/T31405-2G15
This standard is applicable to the comparative test of high temperature cathodic stripping performance of buried temporary pipeline insulation external anti-corrosion coating with cathodic protection and operating temperature higher than normal temperature.
This standard provides the test method for the cathodic stripping performance of anti-corrosion coating immersed or completely immersed in high temperature solution. If the test piece is required to be tested at room temperature, SY/CC37 shall be adopted. If the test piece cannot be immersed or soaked, SY/TC094 may be adopted.2 Normative or applicable documents
For the documents listed below, please note that the version of the date is applicable to the main product. From the illegal date of the shore document, its latest version (including all the repair orders are subject to this document, Y, T037 pipeline aldehyde layer to the most case! Separation test. SY/T0066 Steel case layer thickness length measurement method (magnetic strength) pipe window is the tailor-made shadow test method bonding main military Bo method SY/T 0094+
3.1 The test level is rat-proof. Consider the whole hole of the anti-rat, but the test piece has been immersed in the three-solution liquid market, and the test piece is tightly connected to the source of the flow. The source of the blast and or the light of the super-operation, the sealed parts are subjected to a certain ratio of the distribution, avoidance and sealing. The general international certification point inspection is carried out at a low setting and high level.
3.2 During the test, the current in the test circuit and the potential of the test piece relative to the reference electrode are measured regularly. After the test, the separation of the test piece is observed, and the anti-tumor layer radiation is measured. The test results are evaluated. 4 Test equipment
4.1 Test container
The container is made of materials that do not react with the electrolyte solution and can withstand the test temperature, and is suitable for the circulation of the electrolyte solution. A cylindrical glass container with a diameter of about 300mm, a height of about 300mm, and a volume of not less than 19L is usually used. The bottom of the container is flat to accommodate the rotation of the magnetic stirring bar. The size of the container should meet the following requirements: the test piece should be hung vertically in the container, and the distance between its lower end and the bottom of the container should be not less than 25mm; the interval between the test pieces is not less than 38mm, and the vertically suspended auxiliary anode is placed at an equal distance from each test piece, and the distance is not less than the test piece spacing;
-The distance between the test piece and the side wall of the container is not less than 13 mm; The depth of the electrolyte solution should ensure that the specimen is immersed in it. And comply with the relevant provisions of 6.2: A reference electrode is placed concavely at any position in the container with a distance of not less than 38mm from the specimen and the anode. 4.2 The auxiliary anode
Should be made of metal with low consumption rate and connected with an insulated copper wire sealed by the factory, 1
GB/T31405--2015
4.3 Wire
Insulated copper wire with a cross-sectional area greater than 2mm\ is used to connect the auxiliary anode and the specimen. It should be welded to the non-immersed end of the specimen, and the welding position should be covered with insulating material. There may be joints on the wire, but it should be connected to the welding piece by welding or mechanical crimping. 4.4 Tools for making artificial defects||tt ||Use a common drill bit to create artificial defects, and its diameter should comply with the relevant provisions of 6.4. When preparing small diameter pipes (such as 19mm in diameter), a drill bit with a flat front end can be used to prevent perforation of the metal wall of the pipe. When conducting physical inspections, a sharp knife with a safety handle is required.
4.5 Multimeter
4.5.1 Multimeter 1: The internal resistance value is not less than 10MQ, and the measurement range is 0.0IV~5V, which is used to measure the additional voltage of the specimen (relative to the reference electrode).
4.5.2 Multimeter 2: The internal resistance value is not less than 11M0, and the voltage drop as low as 10μV can be measured on the test circuit. 4.5.3 Multimeter 3: Used for preliminary testing of the apparent resistance of the anti-corrosion layer. 4.6 Reference electrode
Use a saturated calomel reference electrode.
4.7 Thermometer
Two mercury thermometers with an accuracy of ±1°C. One of the thermometers is fully immersed to measure the temperature near the bottom of the container, and the other thermometer is partially immersed to measure the temperature near the front of the container. 4.8 HeaterWww.bzxZ.net
With a built-in magnetic stirrer or similar device, it is used to heat and stir the electrolyte solution. The heater is adjustable and can control the internal temperature of the test container within the range of the set temperature ±1°C. Another method of heating the test piece is internal heating, and the pipe can be filled with heat-conducting materials (oil, steel chips, etc.). Placing the thermocouple or thermometer and the heater in the heat-conducting medium can also effectively control the temperature of the test piece. 4.9 Regulated DC power supply
Can provide a regulated voltage condition of 1.50V±0.01V, which is the voltage between the test piece and the reference electrode. 4.10 Magnetic thickness gauge
Measure the thickness of the anti-corrosion layer according to SY/T0066.
4.11 Standard resistor
12±0.01Ω, power not less than 1W, used for current loop shunt. 4.12 Variable resistor
1002 winding potentiometer can be used, power not less than 25W. 4.13 Carbon or stainless steel electrode
For temporary use, with voltage-resistance meter to measure the initial state at the leakage point of the test piece. 2
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4.14 Additional connecting wire
The cross-sectional area is greater than 2mm, insulated copper wire, 4.15 Copper terminal
GB/T31405-2C15
Used on the terminal distribution board, used with spring wire clamp or knife switch. The function is to reverse or disconnect the circuit. Spring wire clips cannot be used to reverse the electrodes or test pieces located at the top of the test cell. 4.15 Plane area meter
0.5% concentration.
5 Reagents and materials
5.1 Direct solution: Drinkable tap water or water with relatively high purity (either distilled water or deionized water) prepared with a liquid containing 1% mass of sodium phosphate and sodium carbonate (the following must be added) and the liquid H should be 25a·cm500·c5.2 Pipe end sealing materials: can be used products, stone, epoxy grease or other heat-resistant materials, including elastomers or other materials that can withstand long-term testing.
5.3 Adhesive: used to make non-conductive air devices, and suitable for the support of the method and calibration. This invention is used to connect the inductive difference of the device.
e, the test sound is taken from the pipe with the home layer, which has a generation of decay, and the main home point. 62 The test area of the test piece is the surface between the bottom seal and the immersion line. The surface before the bottom seal should not be confirmed as part of the test area. The test piece is a section of the disease-proof layer of the southern bank with an appropriate diameter. The immersion area is not less than 23200mm, with 92900m as the reference.
6.3 Before making artificial defects, the leakage points of the anti-corrosion layer and the effective injection of the end seal should be tested according to the following method: immerse the test piece and the carbon or stainless steel electrode in the electrolyte solution, connect the - end of the multimeter to the test piece, and the other end to the carbon or stainless steel electrode, measure the apparent resistance of the test piece's anti-corrosion layer, and then swap the connectors of the multimeter and test again: and record the test results. The apparent resistance value obtained from the two measurements shall not be less than 1000Mn. The test can also be carried out under the condition of less than 10Mn. The test conditions should be considered when evaluating the results.
6.4 Drill a radial artificial defect hole in the middle of the immersed section of the specimen and record its diameter. When drilling, make sure that the top of the drill bit completely enters the steel pipe wall, and the edge of the cone is flush with the outer surface of the steel pipe. The drill bit diameter should not be less than 3 times the thickness of the anti-corrosion layer, and should not be less than 6mm. The pipe wall should not be drilled through. For small-diameter pipes, it is possible to be penetrated. A standard 60° drill bit should be used to start drilling, and then a drill bit with the cone edge ground off should be used to complete the drilling.
6.5 The pipe end above the immersion line should be provided with a correct support method and a separate wire: for power supply, welding or marking on the pipe. The end protruding from the immersion line, including the hook and the wire connection device, should be protected and sealed with insulating materials. Sub-test steps
7.1 Immerse the test piece in the electrolyte solution and connect it to the anode. The single test piece is connected according to Figure 1, and the multiple test pieces are connected according to Figure 2. The defect hole should face or face away from the anode.
GB/T31405—2015
7.2 Adjust the DC power supply or rheostat to keep the potential E between the test piece and the saturated calomel reference electrode in the range of 1.50V±0.01V under the test temperature. The reference electrode is immersed in the electrolyte solution only during measurement. 7.3 Use a heating and stirring device to make the electrolyte solution reach the test temperature within 4h±1h. During the test, the temperature fluctuation from the surface to the bottom of the electrolyte should be controlled within ±3%. 7.4 Artificial defect holes may be completely or partially blocked by impurities or salt deposits formed during the test, and do not need to be cleared during the test.
7.5 Mark the position of the immersion line on the outside of the test container, and add preheated distilled water or deionized water every day to maintain the liquid level.
7.6 From the start of the test, the potential and current should be measured every day. The maximum continuous stop measurement is 3d, and then continuous monitoring should be carried out for 2d; after stopping the measurement for 1d or stopping the measurement for 2d, at least 1d should be measured. At the beginning and end of the test, continuous measurements should be taken for 3 days and 2 days respectively. 7.7 The measured value at the beginning of the test should be the average of the measurement results on the second and third days after the specimen is immersed. The measured value in the middle and end of the test should be the average of the measurement results on the same day and the previous day. 7.8 The following measurements and adjustments should be made during the test: a) Potential E between the specimen and the reference electrode: The circuit of the anode or the specimen should not be disconnected during the measurement, and a multimeter should be used for measurement. E should always maintain the potential value specified in 7.2 during the test, otherwise it should be adjusted. h) Current I1 between the specimen and the anode: After measuring and adjusting E, I can be determined by installing a multimeter in the test circuit to measure the voltage drop across the 10-Ω standard resistor. 3
Description:
-glass container;
2-electrolyte bath:
anode,
reference electrode;
immersion line;
6--plastic plate 1 for test container
7-connection board;
8-multimeter 1;
square meter 2;
an alligator clip or knife switch;
10resistance;
DC power supply,| |tt||Note: For multiple test pieces in the same test container, a rheostat box should be used as shown in Figure 2. Figure 4 Test apparatus for high temperature cathodic disbonding test
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-Thermometer,
Test piece;
Magnetic stirrer,
Magnetic stirring heater or equivalent
Description:
Reference electrode:
Anode;
100 0, 25W variable resistor divider);
DC power supply:
1 n standard resistor, accuracy ±1%;
Test piece.
Measure the current at the AB end
Measure the voltage at the AC end
Note: Adjust the DC voltage to below 3 V, and then adjust each voltage divider to make the AC voltage 1.5 V. Figure 2 Current diagram of cathode stripping test
GB/T 31405—2015
GB/T31405—2015
150.22 ±12.70
Description:
Bottom of dense warp:
Artificial defect hole;
3·Immersion line;
Comparison milk:
Pins are messy;
6——-Connecting wire,
215.11 on 12.70
Sealed wire joint;
Plug or cover.
111.30±6.33
Figure 3 Schematic diagram of specimen preparation and installation
213,35
Unit is mm
Polarization potential E1: Connect one end of the multimeter to the reference electrode and the other end to the specimen, disconnect the connection line between the anode and the specimen, and pay close attention to the voltmeter. As the reading decreases, it has an obvious pause at the polarization point. The voltage value at this time is E1. 7.9 The test cycle is generally 30 d, including preheating and cooling time, and longer test cycles may also be specified. 7.10 After the test, physical inspection should be carried out immediately as follows: a) Before inspection, first clean the test piece with tap water close to room temperature, and do not damage the visible damage to the anti-corrosion layer. b) Visually inspect the entire immersion area to check whether there are new leaks and the loosening of the anti-corrosion layer at all points (including the edges of the artificial defect hole).
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GB/T31405—2015
c) Using the recommended dimensions of each part in Figure 3, drill a comparison hole in the anti-corrosion layer according to the drilling method for artificial defect holes in 6.4.
In the center of the comparison hole, use a sharp knife to cross-cut through the anti-corrosion layer in a mitre shape through the center of the defect hole, and then use the tip of the knife to pick up the corroded layer. According to the difficulty of lifting, the bonding state between the anti-corrosion layer in the soaking area and the surface of the steel pipe is divided into three situations: cannot be lifted, easy to lift and lifted. Use the same method as d) to cut through the anti-corrosion layer through the center of the cross-shaped cut at the artificial defect hole in the soaking area, and then try to pry up the anti-corrosion layer with the tip of the knife. The area of the anti-corrosion layer that is easier to lift or leave than the comparison hole is the peeling area: pile up transparent coordinate paper on the artificial defect hole, draw the outline of the lifting area, and use plane multiplication to obtain only the lifting area of the artificial defect. You can also calculate the lifting area by counting the squares on the coordinate paper. Use the same method to calculate the lifting area of the comparison hole, and the difference between the two is the peeling area.
8 Report
The test report should include at least the following information (see Appendix A): a) All identification of the test piece. Including:
Name and number of the anti-corrosion layer;
-Dimensions of the steel pipe:
-Source of the anti-corrosion pipe section, production date and batch number; Maximum and minimum values of the thickness of the anti-corrosion layer; Design area;
Size and number of the initial artificial defect holes; Date of start and end of the test.
b) The relevant resistance of the test piece, expressed as, measured before the artificial defect is made. c) The peeling area at the end of the test, expressed in mm or equivalent circle diameter mm, or both names are used at the same time; t) Provide the following measurement results at the beginning, middle and end of the test: current Ii expressed in μA or -lgI, (I, in A); the difference between potential E and potential E,, △E = E, -E,; the change in AE, I, or -lgI from the beginning to the end of the test; e) The temperature of the electrolyte at approximately the same time of each working day. f) Other possible relevant information.
9 Precision and Bias
9.1 For two adjacent test pieces taken from a pipe with the same anti-corrosion coating, the precision is limited. Assuming that the pipe surface conditions and the anti-corrosion coating material are the same during the production process, non-adjacent test pieces under the same production conditions, or test pieces taken from different lengths of the pipe, can represent different production process conditions. Repeatability and reproducibility can be used to judge the acceptability of the results (these precision data are approximate values based on limited data, but they provide a reasonable basis for judging the importance of the results). 9.2 Repeatability (): The equivalent circle diameter calculated by the operator in the laboratory using this standard test method for two results of the same test piece is not greater than 25 mm, and the lgl obtained is not much different from 1. D = (A/0.785)1/2
D——equivalent circle diameter, in millimeters (mm);.+-..----( 1
GB/T 31405—2015
---peeling area, unit is square millimeter (mm\); 0.785
--coefficient derived from the formula.
9.3 Reproducibility (R): The result of the test of the same specimen by different operators in different laboratories, the equivalent circle diameter D calculated according to formula (1) is not greater than 25 mm,Or the difference between the -lgII (I1 in A) obtained by different laboratories is not greater than 1. -iiiKAoNhiKAca
Sample name:
Anti-corrosion coating type:
Client:
Test start month:
Appendix A
(Informative Appendix)
Data record form for high temperature cathodic stripping test of pipeline anti-corrosion coating Report number
Production period:
Production batch number: ． ．
Thickness of anti-corrosion layer at artificial defect hole (mm): Maximum diameter of artificial defect hole (mm):
Location of artificial defect hole: (1)
Test area (mm2):
Test duration
Physical inspection at the end of the test
Test results
Electrolyte
Liquid temperature
Artificial defect pick-up area
Comparison hole pick-up area
Stripping height area
Test End
Average value:
Test temperature:
Initial apparent resistance value Positive connection
(E:-E)
Change area of parameter measurement from the beginning to the end of the test
GB/T31405—2015
Page, total _ pages
Electrolyte:
MO Reverse connection
Average value
When diameter D
.logl,
GB/T 31405-2015
Ninghua People's Republic of China
National Standard
Test method for high temperature weak peeling of corrosion coating on pipeline GB/T 31405-2015
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