SY/T 0544-1995 Technical requirements for solvent-based internal coatings for petroleum drill pipes
Some standard content:
Petroleum and Natural Gas Industry Standard of the People's Republic of ChinaSY/T 05441995
Specification of internal coating for pctroleum drill pipe solvent-based coatings
Technical conditions
Specification of internal coating for pctroleum drill pipes1995-11-08 Issued
China National Petroleum Corporation
1996-05·01 Implementation
Introduction
3 Technical requirements and test methods
4 Product certification, storage, packaging and transportation
5 Quality certification
6 On-site storage and use
Appendix A) Drill pipe coating test method (knife picking method) Appendix B (Standard) High positive density test method (Standard) Coating thickness determination method
This standard directly adopts the American Society of Corrosion Engineers NACFTM0384≤T film thickness is less than 10mm (0.25m1 m) steel pipe internal coating leakage detection standard: This standard is suitable for "film thickness less than 0.25mm1m steel pipe internal coating detection, widely adopted abroad
This standard is called the standard, through the reference in this standard and constitute the entire provisions of this standard. These standards are all test and inspection standards, and will be revised and published in the future. The latest version shall prevail. Appendix A, Appendix B and Appendix C of this standard are all appendices of the standard. This standard was proposed and approved by the Oil and Gas Drilling and Pipeline Construction Design Professional Standardization Committee. Drafting unit of this standard: First Machinery of North China Shizhou Administration Bureau! Jiang Xingrong
Main drafters of this standard Fu Jinlin Zhang Yuansheng Xian Guixin Zhang Tongmin
Petroleum and Natural Gas Industry Standard of the People's Republic of China SY/T 0544-: 1995
Specification of solvent-based coating internal coating for oil drill pipes Specilication of internal coating for oil drill pipes This standard specifies the technical requirements and test methods for the internal coating of petroleum needle rods with floating agent coatings, product marking, storage, loading and unloading and transportation: quality certificate and well site storage and use. This standard is applicable to the internal coating of drill pipes of various types and specifications of API Sc5. The internal coating of this standard is used under the condition that the concentration of the internal layer of the natural gas drilling fluid is not higher than 24 and the drilling fluid PH is 12.5. 2 Reference standards
The following standards contain the parent materials, which are referenced in this standard and constitute this standard. At the time of publication of this standard: 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: GB1724-79 Coating fineness measurement method
CB117279 Paint film-preparation method
(B3186-82 (88) Material sampling
GB/T8923-88 Evaluation of steel surface rust grade and rust removal grade before painting Steel surface decay machine grade before painting (comparison sample method) GB/ T 1328S9:
SY006392 Test method for leak detection of pipeline anti-drinking layer Non-destructive measurement method for pipe anti-separation layer (magnetic method)SY 0066 22
SYJ4042~39 Technical standard for powder internal coating of steel pipeline Drill thread grease
SY 5198-$7
SYT 5360bzxZ.net
94 Treatment and use of petroleum drilling tools Square drill bit, drill pipe, joint NACETMO!S5 Evaluation of the performance of plastic anti-corrosion internal coating of pipelines with high positive sign NA (ETM0384 Detection of leakage of internal coating of steel pipe with dry film thickness less than 10 mils (0.25m1m) APSp sD drill specification
ASTM D714 Determination of the degree of blistering of color paint
3 Technical requirements and test methods
3.1 Requirements for drill pipes before refurbishment
3.1.1 New drill pipes
The supplier of drill pipes shall provide the quality certificate, commodity inspection certificate and supply list for each batch of new drill pipes: 3.1.2 Before supply, the drill pipes shall be inspected and graded according to SY/T5369 (with grading attached): Old drill pipes and repainted drill pipes that meet the first and second level quality standards shall be coated, and a supply list 3.2 shall be provided. Technical requirements for coatings
3.2.1 The technical requirements for polyester materials shall comply with the provisions of the Taiwan National Petroleum Corporation. Approved on November 8, 1995 and implemented on May 1, 1996. Tightness (falling method;
high retreat and high injection test
ph.3.5.1+h'c.
70MPa-IGh
Properties:! This test is for the composite polyester layer of the paint and the surface. SY/ T 0544-1995
Table! Technical requirements for coatings
Technical requirements
Not less than Class B
No bubbles, no change in adhesion
Test methods
See GB1724
See Appendix A (standard list)
British SY4042: Appendix
See Appendix (limited to the standard)
3.2.2 The coating manufacturer shall provide product description, quality inspection report: production phase II and effective storage period. 3.2.3 Coatings of different brands: Before the first use, they shall be tested according to the items specified in Table 1. They can only be used after all the items are qualified. 3.2.4 When the batch of coatings is returned to the factory, samples shall be taken according to the provisions of GB3186, and the fineness, viscosity, thixotropy index, volume content, and time of stock shall be tested according to the technical indicators of the production of polyester materials. They can only be used after all the items are qualified. 3.2.5 If the coating exceeds the specified effective storage period, it should be re-tested according to 3.2.4 before continuing to use, and all technical indicators should be met. 3.3 Coating structure and technical conditions 3.3.1 The coating consists of primer and topcoat: the dry film thickness is 125~22511, and the number of coatings is determined by the performance of the coating. 3.3.2 The inner surface of the new pipe body and the outer thread head shall be fully coated, and only the two buckles of the small end of the internal thread shall be coated. 3.4 Process requirements 3.4.1 The inner surface of the bell rod shall be pre-treated before coating, and the surface roughness shall reach R125-7021 according to GB/T13288, and the rust grade shall reach S221/2~3 according to GBT8923. 3.4.3 After each baking of primer and topcoat, the residence time before re-coating shall not exceed 24.3.5 Factory inspection
Products shall be inspected after the coating is cured and cooled. All inner coating drill rods shall be inspected one by one according to the following requirements. The quality index shall be returned to the original quality index.
The surface of the metal coating of the drill rod shall be inspected by a gauge, which shall be flat and even, smooth, without bubbles, orange peel and sagging and other visible defects. 3.5.2 Dry thickness
SY7 T 05441995
1 The coating thickness gauge should be used to measure the coating thickness. Four points should be measured on the cross section of the coating at both ends of the internal and external threaded joints, 9" apart. The measurement method and sequence are shown in the Appendix (Appendix of the Standard). 3.5.3 Points
The number of leaks in the full length of the inner coating of the drill pipe shall not exceed 5. Test equipment and test method NACLTM0384 are required to be implemented
3.6 Type test
3.6.1 Open test conditions
The type test adopts random sampling method, sampling in the storage area of the finished product of the inner coating drill pipe, and the sampling method of Appendix B (Appendix of the Standard)! 422 is used. Each item shall not be less than one sample. After inspection Only qualified products can be put into production. In any of the following situations, type tests shall be carried out:
When the paint is replaced by a different manufacturer or a paint with different performance; When the main equipment and process undergo major changes that may affect product performance; )
) During normal production, the product should be inspected once a year. When the product is stopped for more than one year and resumed production: ) When the national quality supervision agency proposes a type test. 3.6.2 Type test requirements
a) Adhesion of silt layer:
The inspection should not be lower than Class B. The inspection method and quality judgment are shown in Appendix A (Appendix of the standard); b) High humidity pressure test:
The technical requirements are the same as those in Table 1. The sampling and test methods are shown in Appendix B (Appendix of the standard) 4 Product marking. Storage, loading and unloading and transportation
4.1 Product marking
4.1.1. Apply drill end thread grease
After the rod is inspected and cleaned, apply a layer of neutral drill thread grease (see SY5198) and put on the Huatu and front cap: send to the stand to let the product mark. 4.1.2 Aluminum outer coating
The outer surface of the drill pipe is sprayed with neutral transparent anti-separation material or brushed with surface anti-corrosion coating, which is required to be smooth and even without peeling. 4.1.3 Paint is bad
Mark-self-color paint spraying, the font is Fangsong or Kaishu, the code is capital Latin letters, the number is Ninghechuan A fold number, and the font size should be the same as the original mark symbol. 4.1.4 Paint printing mark content and order
a) Trademark: silt layer factory trademark or! Name:
b) Specification: Pipe outer diameter wall thickness (in millimeters): Silver grade: E, X, G or S grade
d) Standard: ××××××;
) Production month: ××××,
4.1.5 Paint and mark position
The paint and mark shall be printed on the outer surface not less than 610mm away from any end face of the station rod, but the marking direction of the same batch of rods shall be consistent. 4.2 Product storage
4.2.1 The ground of the product storage site should be flat and solid. The products should be classified and stored in the finished product area that has been clearly marked. 4.2.2 There should be two pads on the surface. When the site is a concrete floor, the height of the drill mark from the ground shall not be less than 0.2m: when the site is a construction site, it shall not be less than 0.511: The drill should have a support point. The pads between each layer of drill rods should be aligned up and down to prevent the drill rods from bending. At the same time, there should be molds at both ends of the pads to prevent rolling.
SY/ T 05441995
4.2.3 Drill rods can be stored in multiple layers, and the stacking height shall not exceed 311. 4.2.4 Finished product delivery! Bottles, the protective holes at both ends of the drill pipe should be blocked. 4.3 Product loading and unloading
4.3.1 Use appropriate lifting wheels to lift and place gently. Do not use iron levers, steel pipes and other hard objects to move the drill pipe inside the rod: good protection should be provided
4.32 When loading, there should be more than three rows of cushion columns at the bottom of the rod: the spacing should be appropriate to bear the weight evenly and prevent bending. The load between the layers must be small: the rope should be used to tie the holes to prevent the petals from loosening during transportation. 4.3.3 The installation height should be in accordance with the national transportation safety regulations. 4.3.4 The coating should not come into contact with corrosive substances that may damage it during transportation. 5. Quality certificate
The inner clean layer drill pipe produced by Guan Guang should have a quality certificate issued by the supplier's quality inspection department. The quality certificate should contain the following contents: supplier's name and buyer's name:
h including the interval number
l! Product name, specification (diameter and wall thickness), steel grade; technical indicators and inspection results; 9) Delivery time (year, month): h. Except for the inspection, the company shall record other contents that the company considers necessary to clarify, and the storage and use on site shall be sufficient in depth and depth. (.2 The chain shall be able to roll without rolling. (.3 It is forbidden to insert hard objects such as iron directly into the drill rod to move the pipe. 6.4 It is forbidden to place heavy objects on the stored pipe. 6.5 The drill pipe filter shall not be allowed to be used. 6.6 Drilling is not necessary. The inner surface of the drill pipe must be rained through the inner coating, and the tools must have a team device that does not damage the coating. The drilling rig should be equipped with retaining caps at both ends, and the holes at the ends of the protective caps should be blocked. (1.7 68 The normal environment of non-drilling liquid should be included in the drill pipe
() When spraying the drill pipe, the following requirements should be followed: Before spraying: let the cooling water fill the entire drill pipe; spray the sealant and keep the water in the drill pipe for more than 5 minutes. 4
Appendix (Appendix)
41 Scope of application
Drill pipe coating adhesion test method (blade picking method) This method is applicable to the adhesion test of the coating inside the drill pipe. A2 Method Summary
Use a sharp knife to make two notches on the drill pipe, and then use the tip of the knife to pick up the coating that is not broken by the two notches, and check whether the adhesion of the coating picked up is qualified
Test steps
Use a sharp knife to make two parallel notches in the length direction of the pipe body. The distance between the notches is 3111m, and each notch is about 2~3cm long. When making, make the tip of the knife perpendicular to the coating surface, and the cutting should be Stable and without shaking. A3.3 The cut should penetrate the coating to the metal substrate. Use the tip of the knife to pick up the coating from the cut area to check the adhesion of the coating to the metal around the cut. 13.4
Record the test results.
Result evaluation
Divided into five levels:
Level A - The coating cannot be picked up from the metal substrate. The metal can only be seen where the knife marks are; Level B
A small part of the coating can be picked up, but more than 50% of the coating is intact: that is, more than 50% of the coating is picked up:
(Level 1
1) All coatings can be picked up, exposing the metal substrate; Level E
-The coating is separated from the metal substrate without the use of a knife. Appendix (limited to the appendix of the standard)
Autoclave test method
This method is based on NACFTMO B1 Description of the 1SS
B1.1 This test method uses the following test conditions to evaluate the performance of the plastic coating on the steel pipe: the test is carried out in a high pressure chamber at a certain temperature and pressure.
B1.2 The test method is a standard test method that can evaluate the overall performance of the plastic coating on the steel pipe. B2 Principle
In a corrosive medium, at a certain temperature and pressure, the protective performance of the steel pipe coated with the plastic coating may change. The high pressure chamber is a static chamber in which the coating is placed to a certain corrosion environment and temperature and pressure are applied, so that the influence of the above factors on the coating performance can be observed.
3 Test Equipment
B3.1 High pressure chamber
The high pressure chamber is a container that can withstand the maximum pressure and temperature and is equipped with a pressure gauge and a temperature controller. 33.1.1
.2 A monitor shall be provided to ensure that the temperature and positive pressure remain at the specified values during the entire test. The autoclave shall be made of suitable materials to resist corrosion and attack by the test medium. 3.1.37
B3.2 Heating of the test vessel
The heating method of high pressure energy shall enable the heating to be carried out evenly. 3.2.1
The heating zone shall extend from the bottom of the test vessel to the point where the sample is submerged. It is necessary to ensure that the sample and the medium are heated evenly. B3.2.21
The temperature shall be controlled within 6°C of the test temperature. B3.2.31
B3.3 Verification of high pressure
For the continuation of the test, the method of increasing pressure shall provide and maintain a known and reproducible positive pressure and gas concentration. B3.4 High-pressure flow meter safety
B1.4.1 All safety regulations recommended by the manufacturer should be followed. B3.4.2 Attention should be paid to understanding the current safety knowledge of high-temperature and high-pressure flow measurement equipment, and also understanding the safety knowledge of flammable and toxic gases (light H2O3).
34 Test specimens
Test the coating performance in the actual test air. The test specimens can be made according to GB1727. The surface of the test specimens should be sandblasted to meet the surface roughness and rust removal standards of 14.1
The coating can be applied by spraying or brushing. , the film thickness is the same as the pipe body B4.2 For the finished product to be tested, the sample should be obtained from the inner coating pipe body. B4.2.1 In order to evaluate the performance of the state-produced coating product, a sample should be randomly cut from the pipe body on the production line. 14.2.2 The sample can also be obtained by the method of "opening a skylight". That is, take a drill sample and make a "skylight" on it, and then make the sample into a shape of the same size as the "skylight" and bundle it with the pipe body. According to the process flow of the same batch of drill pipes, it is made on the production line: when sampling, it is disassembled to open the "window" drill and sample size. Figure 2. B4.4 Before the test, the specimens should be visually inspected and recorded. B4.5 Measure the thickness of the paint layer according to SY0066: at least 100 points should be measured. B4.6 Detect leaks according to method B in SY0063-92: the coating should have no leaks. B4.7 If the volume of the autoclave allows, several specimens can be tested at the same time. B4.8 A comparison specimen with known performance should be placed in the test chamber at the same time during each test. 0
Figure 1 "Skylight" drill rod size diagram (unit: 11).
Figure 2 "Skylight" sample size diagram (unit: mm) 550
Note: The dimensions marked in the area and figure are based on the drill rod with a diameter of 127mm. Drill rods of other sizes can refer to the requirements to manufacture appropriate inch samples
B5 Test steps
The test should be carried out in accordance with the safety regulations and operating methods recommended by the high-pressure manufacturer. B5.2
Verification conditions:
B5.2.1. The test conditions should be determined according to the items being tested.) The sample should be fully immersed in the medium.
It is recommended to place three samples (including one comparison sample) each time: there should be a certain distance between each sample b)
B5.2.2 After the test, the kettle body should be cooled to 93, and then reduced to normal pressure at a uniform speed within 15 to 30 minutes, and finally the sample should be taken out:
B6 Evaluation
After taking out the sample, an immediate appearance inspection should be carried out to see if there is any swelling or softening. The sample is then cooled to room temperature for further inspection. The sample should be compared with the sample that has not been tested to see if there is any blistering and adhesion change. B6.1 For defects such as softening, swelling, color change, and foamy bubbles or looseness inside the coating, use the following standard meters to measure: a) No change; b) Slight change; c) Severe change: d) Severe deterioration; B6.2 Small measurements shall be evaluated according to Appendix A (Appendix to the standard). B(.3 Blistering shall be evaluated according to ASTMD714.
B7 Repeatability of coating performance
For the same coating, as long as the test conditions are the same, the test results should be the same. If the test results are not repeatable, double-check the reasons: or conduct further analysis on the sample. Repeat the test. B8 Test result record
Autoclave test data record table (format) Recorder
Test start time
Test medium
Polyester batch number
Detailed method
Test end time
Test pressure
Test temperature
Test sample appearance description: Changes in softness, color, bubbles or looseness inside the coating Test conclusion:
Blistering condition
Attachment
Attachment C (standard gradual recording)
This method is formulated with reference to SY (1066
(1 Method Overview
Coating Thickness Determination Method
(1.1 This method is applicable to the non-destructive measurement of the thickness of the non-magnetic coating on the inner surface of the drill pipe. C1.2 The measurement of coating thickness shall not only comply with this method, but also comply with the provisions of the relevant national standards (specifications) in force. (1.3 This method should be used with a temperature-free measuring instrument. The coating pressure is measured based on the change in the magnetic flux or magnetic attraction between the probe and the base metal.
(2 Instrument
The instrument should be suitable for measuring the flat or round magnetic film coating thickness, and can be used for all sizes of TAPISeDm. The measurement accuracy is 2% of the time of each gear. 3 Instrument Calibration
(1 Before using the instrument, it must be connected to the production" Instructions: Use appropriate standard pieces for calibration. When used, keep the interval between the new school and the small magnetic standard pieces with uniform thickness. The thickness of the tube should be as close as possible to the estimated value of the coating thickness to be measured. It should be placed on smooth and clean low-light steel to make it in close contact with the base metal. A single layer of appropriate thickness should be used and replaced frequently, because it is easy to produce waves: when calibrated on the surface, it is convenient to use and is easier to buy than the coating test piece. There are also instruments and a critical original degree of the base metal. When the basic metal is developed through this degree, the measuring instrument will not be affected by the increase in metal density. The critical degree should not be read. The nature of the base metal original. Special manufacturing! Ratios not given, determined by testing, C34 Coating Limit Standard: This calibration standard is made by pasting a magnetic coating of known thickness on a &mm thick mild steel plate. The thickness should be as close as possible to the estimated coating thickness of the coating to be measured. Note: If the coating thickness is relatively high, the use of a flat surface standard is not possible, then the calibration standard should be pasted on a substrate with the same coating thickness as the coating to be measured and calibrated.
C4 Measurement Steps
The instrument is operated according to the manufacturer's instructions. (.4.1
(42) The coating area at both ends of the needle rod should be 90 degrees apart. The four points at both ends should be measured (43) Use a bipolar measurement, the poles should be located on the same plane as the surface of the high-rise surface (4.4 If the surface thickness of the metal part is greater than 25% of the coating thickness, its effect on the measurement accuracy must be considered. C4.5 Under the premise of not damaging any coating material, the dust and grease should be removed by appropriate methods. The magnetic probe should not be contaminated before measurement. (4.6 The measuring instrument and the measuring method are related to the author's skills. For example, the pressure applied to the probe and the rate of application of the balance are different. The author can reduce or eliminate this effect by performing reverse calibration and measurement, or using a constant pressure probe. The probe must be placed perpendicular to the test surface. If it is used in a horizontal or inverted position, it should be calibrated in this position. (4.7 The magnetic instrument is sensitive to the speed at which the magnet is removed from the test position. When used, the speed at which the probe is removed must not affect the thickness measurement. (4.8 The inner diameter of the pipe end is due to the inner diameter of the pipe itself, and the inner diameter of the pipe itself cannot be measured. Therefore, the film thickness of the pipe end must be used to infer the thickness of the pipe body.3 This method applies to temperature-free measuring instruments. It measures the coating pressure according to the change of magnetic flux or magnetic attraction between the probe and the base metal. (2) The instrument should be suitable for measuring the flat or round magnetic film coating original original, applicable to all specifications of TAPISeDm, and the measurement accuracy is 2% of the working time of each gear. 3 Calibration of the instrument (1) Before using the instrument, it must be calibrated with appropriate standard pieces according to the manufacturer's instructions. When using, keep the intervals specified in the calibration. (2) Small magnetic calibration standards with uniform thickness can be used. Test pieces with known thickness and known coating thickness can be used. They can be provided by the instrument manufacturer and purchased by you. C33 Calibration The thickness of the standard foil (foil): the thickness of the tube should be as close as possible to the estimated value of the coating thickness to be measured. It should be placed on a smooth and clean low-carbon steel: so that it is in close contact with the base metal. A single layer of appropriate thickness should be used and replaced frequently, because it is easy to produce waves: when calibrated on the surface, it is convenient to use: and it is easier to buy than the coated test piece. There are also instruments and a critical original degree of the base metal. When the basic metal develops through this degree, the measuring instrument will not be affected by the increase in metal density. The critical degree should not be read. It is recommended to interpret the properties of the base metal. If the manufacturer does not provide a ratio, it is determined by scratching and testing. C34 coating limit standard: This calibration standard is made by sticking a magnetic coating of three known thicknesses on a &mm thick low-carbon steel plate for a long time. The thickness should be As close as possible to the estimated coating thickness of the coating to be measured. Note: If the coating thickness is relatively high, it is not possible to use a flat surface calibration, then the calibration standard should be attached to a substrate with the same thickness as the coating to be measured for calibration.
C4 Measurement steps
Operate the instrument according to the manufacturer's instructions. (.4.1
(42) There should be 90° between the two ends of the needle rod, and four points should be measured at both ends (43) Use a bipolar measurement, and the electrodes should be located on the same plane of the high-level surface (4.4 If the surface thickness of the workpiece is greater than 25% of the coating thickness, its effect on the measurement accuracy must be considered. C4.5 Under the premise of not damaging any coating material, use appropriate methods to measure the coating thickness. Dust and grease should be removed before measurement. The magnetic probe should not be contaminated. (4.6 The measuring instrument and the measuring method are related to the author's skills. For example, the pressure applied to the probe and the rate of application of the balance are different. The author can reduce or eliminate this effect by performing reverse calibration and measurement, or using a constant pressure probe. The probe must be placed perpendicular to the surface of the test point. If it is used in a horizontal or inverted position, it should be calibrated in this position. (4.7 The magnetic instrument is sensitive to the speed at which the magnet moves from the test position. When used, the speed at which the probe moves away must not affect the thickness measurement. (4.8 The inner diameter of the pipe end is due to the inner diameter of the pipe itself, and the inner diameter of the pipe itself cannot be measured. Therefore, the film thickness of the pipe end must be used to infer the thickness of the pipe body.3 This method applies to temperature-free measuring instruments. It measures the coating pressure according to the change of magnetic flux or magnetic attraction between the probe and the base metal. (2) The instrument should be suitable for measuring the flat or round magnetic film coating original original, applicable to all specifications of TAPISeDm, and the measurement accuracy is 2% of the working time of each gear. 3 Calibration of the instrument (1) Before using the instrument, it must be calibrated with appropriate standard pieces according to the manufacturer's instructions. When using, keep the intervals specified in the calibration. (2) Small magnetic calibration standards with uniform thickness can be used. Test pieces with known thickness and known coating thickness can be used. They can be provided by the instrument manufacturer and purchased by you. C33 Calibration The thickness of the standard foil (foil): the thickness of the tube should be as close as possible to the estimated value of the coating thickness to be measured. It should be placed on a smooth and clean low-carbon steel: so that it is in close contact with the base metal. A single layer of appropriate thickness should be used and replaced frequently, because it is easy to produce waves: when calibrated on the surface, it is convenient to use: and it is easier to buy than the coated test piece. There are also instruments and a critical original degree of the base metal. When the basic metal develops through this degree, the measuring instrument will not be affected by the increase in metal density. The critical degree should not be read. It is recommended to interpret the properties of the base metal. If the manufacturer does not provide a ratio, it is determined by scratching and testing. C34 coating limit standard: This calibration standard is made by sticking a magnetic coating of three known thicknesses on a &mm thick low-carbon steel plate for a long time. The thickness should be As close as possible to the estimated coating thickness of the coating to be measured. Note: If the coating thickness is relatively high, it is not possible to use a flat surface calibration, then the calibration standard should be attached to a substrate with the same thickness as the coating to be measured for calibration.
C4 Measurement steps
Operate the instrument according to the manufacturer's instructions. (.4.1
(42) There should be 90° between the two ends of the needle rod, and four points should be measured at both ends (43) Use a bipolar measurement, and the electrodes should be located on the same plane of the high-level surface (4.4 If the surface thickness of the workpiece is greater than 25% of the coating thickness, its effect on the measurement accuracy must be considered. C4.5 Under the premise of not damaging any coating material, use appropriate methods to measure the coating thickness. Dust and grease should be removed before measurement. The magnetic probe should not be contaminated. (4.6 The measuring instrument and the measuring method are related to the author's skills. For example, the pressure applied to the probe and the rate of application of the balance are different. The author can reduce or eliminate this effect by performing reverse calibration and measurement, or using a constant pressure probe. The probe must be placed perpendicular to the surface of the test point. If it is used in a horizontal or inverted position, it should be calibrated in this position. (4.7 The magnetic instrument is sensitive to the speed at which the magnet moves from the test position. When used, the speed at which the probe moves away must not affect the thickness measurement. (4.8 The inner diameter of the pipe end is due to the inner diameter of the pipe itself, and the inner diameter of the pipe itself cannot be measured. Therefore, the film thickness of the pipe end must be used to infer the thickness of the pipe body.
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