This standard specifies a test method for determining the impact resistance of pipeline anticorrosion coatings. This standard is applicable to determining the energy required to damage pipeline anticorrosion coatings under specified drop hammer impact conditions, and provides a method for selecting anticorrosion coating materials based on this performance. SY/T 0040-1997 Test method for impact resistance of pipeline anticorrosion coatings (drop hammer test method) SY/T0040-1997 Standard download decompression password: www.bzxz.net

1 Scope
Petroleum and Natural Gas Industry Standard of the People's Republic of China Test Method for Impact Resistance of Pipeline Anticorrosion Coating
(Drop Hammer Test Method)
Approval Department: China National Petroleum Corporation Date of Approval: 1997-12-31
Effective Date: 1998-07-01
This standard specifies a test method for determining the impact resistance of pipeline anticorrosion coating. SY/T 0040--1997
Replaces SYJ40--1989
This standard is applicable to determining the energy required to damage the pipeline anticorrosion coating under the specified drop hammer impact conditions, and provides a method for selecting anticorrosion coating materials based on this performance.
2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. SY0063—1992 Leakage test method for pipeline anticorrosion layer SY0C66-1992 Non-destructive measurement method for thickness of steel pipe anticorrosion layer (magnetic method) YB(T)1—1980 High carbon chromium bearing steel
3 Overview and significance of the method
This method is a mechanical test method that uses a fixed-mass hammer to drop from different heights to produce point impacts on the surface of the test piece, and uses electrical measurement to detect the damage caused by the anticorrosion layer. The impact resistance of the anticorrosion layer is determined by the amount of energy required to penetrate the anticorrosion layer. The ability of the pipeline anticorrosion layer to resist mechanical damage during transportation, loading and unloading, and installation depends on the impact resistance of the anticorrosion layer. 4 Instruments and equipment
4.1 The impact test machine (see Figures 1, 2, and 3) shall comply with the following provisions. a) Heavy hammer:
The heavy hammer consists of a white hammer head and a hammer body, with a mass of 1.36kg. The hammer head is hemispherical and has a diameter of 15.9mm. It is suitable for a drop range of 0.6~1.2m. For most anti-corrosion layers, when the heavy hammer hits from a height of 0.9m, suitable results can be produced. Note: If the hammer head is processed to Rockwell hardness HRC45 after processing and maintains an impact toughness value of at least 20J, frequent replacement of the hammer head can be avoided. High carbon chromium bearing steel that meets the GCr15 grade in the YB (T) 1 standard can also be used as a hammer head. b) Drop guide tube:
The guide tube is 1.52m long and contains a heavy hammer to guide the drop of the heavy hammer. The drop guide tube is made of steel, aluminum or other suitable rigid materials, and the inner surface is finely processed to reduce the friction when the heavy hammer falls. The drop tube should be equipped with a scale with a graduation value of 2.5mm to measure the drop height of the weight
c) Pipe clamp:
Installed on the base of the equipment, used to fix and position the test piece (perpendicular to the axis of the drop tube). Note: The sliding impact caused by the misalignment of the drop tube and the test piece will lead to irregular test results. For this reason, it is recommended to use a steel V-type clamp with a spring clamp.
d) Equipment support:
SY/T0040—1997
Both the equipment and the test piece should have a firm support so that there is a rigid foundation so that the energy of the weight can be fully transmitted to the test piece. 4.2 Magnetic thickness gauge: Determined according to SY0066. 4.3 Anti-corrosion layer leak detector: Determined according to SY0063. 5 Test piece
5.1 The test piece should be taken from a representative industrially produced anti-corrosion layer pipe section, and the anti-corrosion layer should have no obvious cracks or defects. A seamless steel pipe with an outer diameter of 60mm and a wall thickness of 4mm is used, and the length of the test piece is 410mm. 5.2 Seven test pieces should be prepared for each test.
6 State adjustment
6.1 The test piece should be placed at room temperature of 21-25℃ for 24h before the test. 7 Pre-test
7.1 First, measure the thickness of the test piece's anti-corrosion layer according to the requirements of SY0066, and then perform a leak test on the test piece according to the requirements of SY0063, requiring the test piece to have no leak points.
7.2 Place the test piece that has passed the leak test in a V-shaped pipe clamp, and gently place a heavy hammer on the surface of the anti-corrosion layer, and adjust the zero point of the ruler. 7.3 In order to determine the approximate starting height of the drop hammer, a preliminary test is required. That is, the first test piece is impacted from a height sufficient to damage the anti-corrosion layer, so that it produces damage to the anti-corrosion layer that can be detected according to SY0063. Subsequently, the height is reduced by 50%, and a second exploratory impact is made on a new area on the surface of the test piece. In this way, the test is continued by lowering the height accordingly until no damage occurs. Note: The impact points should be randomly selected on the surface of the anti-corrosion layer, and the distance between the two adjacent impact points should be kept not less than 76mm, and not less than 38mm from the pipe end. Selecting the impact points in any regular way will cause the test to deviate and introduce errors into the test results. 7.4 Repeat the test at the height immediately before the undamaged point to determine whether the approximate height of the average impact strength has been found. Note: In order to make the number of damaged points and undamaged points in the test close, the interpolation method can be used to reduce the height values ​​of the damaged points and undamaged points. 8 Test steps
8.1 This test is carried out at 21~~25℃. 8.2 Start the test at the middle value of the height range determined in 7.4. Maintain a fixed height increment between two tests. 8.3 After each impact, check whether the anti-corrosion layer is damaged according to SY0063. 8.4 If the anti-corrosion layer is damaged during the first impact, reduce the height increment for the next test; if it is not damaged, increase the height increment for the next test.
8.5 In the same way, determine the next impact height by whether the anti-corrosion layer is damaged or not. The height increments of adjacent impact points remain unchanged. Continue to apply this "up-down" method until 20 consecutive impact readings are completed. 9 Calculation
9.1 The calculation formula for impact strength is as follows.
M-9.81X10-5[ho+d(
Wherein: M-average value of impact strength (J); h.-—lowest impact height with the least number of occurrences (cm); t-—impact height increment (cm)
N-—-the total number of times damage occurs or does not occur in 20 tests, the smaller of which is the N value; A-—-the sum of the product of the number of increments above the h. value in all N and the number of occurrences at that height; W..-
weight of a hammer (g).
Note: When calculating the average value of impact strength based on the total number of times the anti-corrosion layer is damaged, a negative sign is used; otherwise, a positive sign is used. 9.2 The calculation formula for the standard deviation is as follows.
（1）
SY/T 0040—1997
Where S.--standard deviation J)
S9.81×10-[1-62d(NB-A'2+0.0737WN2
B--the sum of the square of the number of increments above h in all N and the product of the number of times the height occurs. (2)
Note: Only by correctly selecting the height increment d can the impact strength of the anti-corrosion layer be properly determined. When a 1.36kg hammer is used to test an anti-corrosion layer with a thickness of 0.254~~1.02mm, the height increment should be 5.10~12.7mm. For thicker anti-corrosion layers, a larger height increment is required. If the ratio of the height increment to the standard deviation ( d/s) is less than 0.045 (1/N), the test should be repeated with a larger height increment d, which will improve the estimation of the impact strength value of the anti-corrosion layer.
9.3 Appendix A (Suggested Appendix) illustrates the use of the above two formulas with examples. 10 Test ReportWww.bzxZ.net
The test report includes the following contents.
a) Complete identification information of the test piece:
1) Name of the anti-corrosion layer and its technical standard number; 2) Pipe size (including length, outer diameter and wall thickness) and material; 3) Anti-corrosion pipe manufacturer, production date and production serial number; 4) Maximum, minimum and average thickness values ​​of the anti-corrosion layer; 5) Test date;
6) Other relevant information.
b) Average impact strength value M.
c) Standard deviation S.
1---drop guide tube; 2-tube sleeve; 3-hammer; 4-hammer head; 5-test piece; 6-metal V-type seat; 7-machine base; 8°-lifting pin; 9-positioning screw; 10 frame; 11-pipe clamp; 12-spring; 13-lifting ringFigure 1 Impact testing machine
SY/T0040-1997
Metal V-type seat; b-hammer; c-pipe clamp; d-spring; e-lifting pin; f-hammer head; 1-guide core; 2-M5 standard screw hole; 3-M4 hexagon fixing screw hole, 4-M6 countersunk screw holeFigure 2 Impact testing machine parts diagram ()
SY/T 0040--1997
1—Hole for cap screw; 2—Hole for M4 eyebolt; 3,4 Welding seam; 5—Aluminum tube; 0—Machine base; 7—6mm×6mm square hole; 8—Pipe sleeve; 9—Frame Figure 3 Parts drawing of impact testing machine (II)
Appendix A
(Suggestive appendix)
Calculation example
Use 1.The results of 20 impact tests with a 36kg hammer are shown in Table A1. Table A1 Test results
Number of tests
Falling height
Height increment-0.8cm
Number of breakages=11
Number of unbreakages=9
Number of tests
Falling height
SY/T 0040—1997
At 33.4cm (h.), the number of unbreakages=1; at 34.2cm, the number of unbreakages=3; at 35.0cm, the number of unbreakages=3; at 35.8cm, the number of unbreakages=2. Calculate A and B:
A=(0×1)+(1×3)+(2×3)+(3×2)=15B=(0° ×1) +-(12 ×3)+(22 X3)+(32 X2)=33Calculate according to formula (1):
0*[33.4+0.8（号+
M -- 9.81X 10
15，1
）×1360
Calculate according to formula (2):
S=9.81×10-s[1.62x0.8x(2×33-152)+0.0737×13609
Average impact strength value M=4.69J
Standard deviation S=0.164J
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