JB/T 7870-1997 Thin-walled metal pipes and fittings for sprinkler irrigation
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T7870-1997
Metal Thin Wall Pipes and Fittings for Sprinkler Irrigation
Published on June 20, 1997
Ministry of Machinery Industry of the People's Republic of China
Implemented on January 1, 1998
JB/T7870-1997
This standard is a revision of JB/T7869.2-95 (formerly GB During the revision, JB/T7869.1~7869.2—Technical Conditions for Metal Thin-walled Pipes and Fittings for Sprinkler Irrigation were retained and the three standards were merged into one standard. 95 and JB/T7870-95, and the following modifications have been made based on the actual production, use and development trend of thin-walled metal pipes and pipe fittings in my country:
The requirements for water pressure resistance and the corresponding test methods have been adjusted; - The calculation method of head loss along the way has been added: The inspection rules have been modified;
Appendix C "Test Report Form and Table" in JB/T7869.2-95 has been deleted; The technical requirements that should be specified by the manufacturer in the standard have been deleted; According to the provisions of GB/T1.1-1993, the writing format and expression of the standard have been adjusted. From the date of entry into force, this standard will replace JB/T7869.1~7869.2-95 and JB/T7870-95. Appendix A and Appendix B of this standard are both appendices to the standard. This standard is proposed and managed by the National Technical Committee for Agricultural Machinery Standardization. The drafting unit of this standard: Drainage and Irrigation Machinery Research Institute of Jiangsu University of Science and Technology. The main drafters of this standard: Liu Yulin, Lin Kan. 1
Mechanical Industry Standard of the People's Republic of China
Metal Thin-walled Pipes and Fittings for Sprinkler Irrigation
JB/T7870-1997
Replaces JB/T7869.1--7669.295
JB/T 7870-95
This standard specifies the varieties, specifications, technical requirements, test methods, inspection rules, marking and packaging of metal thin-walled pipes and fittings for sprinkler irrigation.
This standard applies to galvanized thin-walled steel pipes, thin-walled aluminum (aluminum alloy) pipes and various matching pipe fittings for sprinkler irrigation. 2
Cited 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. GB228—87
GB242—82
GB246—82
GB700-88
GB708-88
GB 117386
GB2828—87
GB3091—82
GB 3190-82
GB5213-85
GB 6893-86
JB/T567391
HG 4-329-66
3 Varieties and specifications
Metal thin-walled tubes are divided into:
Metal tensile test method
Metal tube expansion test method
Metal tube flattening test method
Carbon structural steel
Dimensions and allowable deviations of cold-rolled steel plates and strips Technical conditions for cast aluminum alloys
Acceptance, packaging, marking and quality certificate of steel tubes Batch inspection counting sampling procedures and sampling tables (applicable to inspection of continuous batches) Galvanized welded steel tubes for low-pressure fluid transportation
Chemical composition of aluminum and aluminum alloy processed products Deep drawn cold-rolled thin steel plates and strips
Industrial aluminum and aluminum alloy drawing (rolling) tubes
Painting of agricultural and forestry tractors and machinery
General technical conditionsbzxZ.net
Sealing rubber products (ring-shaped)
Galvanized thin-walled steel tubes, nominal pressure is 1000kPa. Thin-walled aluminum (aluminum alloy) pipes, nominal pressure is 800kPa. 3.2 The specifications and allowable deviations of metal thin-walled pipes shall comply with the provisions of Table 1. 3.3. The specifications of pipe fittings are expressed by the nominal outer diameter of the metal thin-walled pipes they match, and the reducer is expressed by the nominal outer diameter of the metal thin-walled pipe matched with the large end of the reducer. The specifications of pipe fittings shall comply with the provisions of Table 2. Approved by the Ministry of Machinery Industry on June 20, 1997
Implemented on January 1, 1998
Outer diameter D
and allowable deviation
Wall thickness S
and allowable deviation
Nominal size
Galvanized thin-walled steel pipe
Thin-walled aluminum (aluminum alloy) pipe
Galvanized thin-walled steel pipe
Thin-walled aluminum (aluminum alloy) pipe
Fixed length L and allowable deviation
Straightness
Quick connector
4 Technical requirements
General Requirements
Non-fixed-size
JB/T7870-1997
Specifications and allowable deviations of metal thin-walled tubes mm
324050606570758090100105110120130150160±1%D
6000;5000
Specifications of fittings
Reducing tubes
JB/T7870-1997
Pipes and fittings shall comply with the requirements of this standard and be manufactured according to the drawings and technical documents approved through the prescribed procedures. 4.2 Galvanized thin-walled steel pipe
The pipe of galvanized thin-walled steel pipe is made of easy-to-weld steel. The steel grade and manufacturing method are selected by the manufacturer. 4.2.1
The inner and outer surfaces of the pipe should have a complete galvanized layer. No leakage, bubbles, local roughness and zinc nodules are allowed. 4.2.2
The cross-section at both ends of the pipe should be perpendicular to the axis of the pipe, and the inclination should not be greater than 2°; the burrs inside and outside the cut should not be higher than 0.5mm. 4.2.3
4.2.4The average weight of the inner and outer galvanized layer of hot-dip galvanized steel pipe is 500g/m (the coating thickness is equivalent to 0.069mm). The allowable deviation is -50g/m; the thickness of the inner and outer galvanized layer of electro-galvanized steel pipe is not less than 0.03mm. 4.2.5 When the galvanized layer of galvanized thin-walled steel pipe is subjected to acid copper immersion test, the sample is repeatedly immersed five times, and there shall be no red copper deposition on the surface of the galvanized steel pipe.
The bonding strength of the galvanized layer of the galvanized thin-walled steel pipe shall comply with the provisions of Appendix A (Appendix to the standard). The zinc content of the galvanized layer of the galvanized thin-walled steel pipe shall not be less than 98.5%. Electrogalvanized thin-walled steel pipes shall be passivated. Hot-dip galvanized thin-walled steel pipes may be passivated upon agreement between the supply and demand parties. 4.3 Thin-walled aluminum (aluminum alloy) pipes
The brand and supply status of thin-walled aluminum (aluminum alloy) pipes shall comply with the provisions of GB6893. The chemical composition of thin-walled aluminum (aluminum alloy) pipes shall comply with the provisions of GB3190. The mechanical properties of thin-walled aluminum (aluminum alloy) pipes shall comply with the provisions of GB6893. The inner and outer surface quality base and internal organization of thin-walled aluminum (aluminum alloy) pipes shall comply with the provisions of GB6893. The cross-sections at both ends of the thin-walled aluminum (aluminum alloy) pipes shall be perpendicular to the pipe axis, with an inclination of no more than 2°, and the inner and outer burrs of the cut shall not be higher than 0.54.4 Performance of metal thin-walled pipes
Phenomenon.
When metal thin-walled tubes are subjected to water pressure test with a test pressure of 1.6 times the nominal pressure, no leakage shall occur. The tensile properties of metal thin-walled tubes shall comply with the provisions of GB228. Metal thin-walled tubes shall be subjected to expansion test in accordance with the provisions of GB242. After the test, there shall be no cracks, splits, weld cracks, etc. at the expanded part of the sample. Metal thin-walled tubes shall be subjected to flattening test in accordance with the provisions of GB246. After the test, there shall be no cracks, splits, weld cracks, etc. at the bending deformation part of the sample.
4.4.5 The combination of metal thin-walled tubes and pipe fittings shall be subjected to running test, and the running time shall not be less than 500h. 4.5 Pipe fittings
The materials used must be accompanied by chemical composition and mechanical property certificates. 4.5.1
4.5.2 The material of stamping parts shall be made of cold-rolled thin steel plate or B3 cold-rolled thin steel plate made of material not lower than 08A1 specified in GB5213, surface quality group, drawing level F. The thickness deviation shall comply with the Class B regulations of GB708. 4.5.3 The chemical composition and mechanical properties of aluminum castings shall comply with the regulations of GB1173. 4.5.4
The material of welded parts shall comply with the relevant provisions of GB700. Other mild steels that are easy to weld may also be used. The rubber compound of rubber seals shall comply with the relevant provisions of Class-2 in HG4-329. The inner wall and joints of pipe fittings shall be smooth and flat, and there shall be no obvious defects such as bumps and flattening at the bends. The inner and outer surfaces of castings shall be smooth, and no defects such as cracks, sand holes, pores, shrinkage, etc. that affect the performance and appearance quality shall be allowed. The weld of welded parts shall be flat, and no defects such as desoldering, leakage, cracks, burn-through, weld nodules, slag inclusions and pores shall be allowed. Welded parts that need to be galvanized shall be welded first and then galvanized. The galvanized layer of galvanized parts shall comply with the relevant provisions of 4.2. The surface of stamped parts shall be smooth, without defects such as wrinkles, marks, cracks and delamination; the edges shall not have flash and burrs. The bonding of adhesive parts shall comply with the relevant bonding process requirements and operating procedures. The strength of the bonding part shall meet the design requirements. The thread shape of the connecting thread must be intact and free of defects such as deformation and missing teeth. The painting shall comply with the relevant provisions of JB/T5673 for water-resistant coatings. 3
JB/T78701997
4.5.15 For the processed surfaces that are prone to rust, anti-rust measures must be taken, but the water quality must not be polluted. 4.5.16 The surface and appearance quality of rubber seals shall comply with the relevant provisions of HG4-329. 4.6 Performance of pipe fittings
4.6.1 For pipe fittings subjected to water pressure, when the water pressure resistance test is carried out at a test pressure of 1.6 times the nominal pressure, plastic deformation shall not occur in all parts of the pipe fittings, and leakage is not allowed at the welding and gluing points. 4.6.2 When the sealing performance test of the pipe fittings is carried out at a test pressure of the nominal pressure, leakage shall not occur. 4.6.3 Quick joints should be subjected to deflection angle test. Deflect the quick joints to the design angle. Under nominal pressure, maintain pressure for 5 minutes, and no leakage should occur.
4.6.4 For pipe fittings with white leakage requirements, self-leakage performance test should be carried out. White leakage performance should meet the design and use requirements. 4.6.5 Pipe fittings used for water suction pipelines should be subjected to vacuum test. The test water temperature is 0-40℃. Deflect the pipe section to the design angle. No air should be inhaled for 5 minutes under 70kPa. The adhesive parts of the adhesive parts should be subjected to pull-out resistance performance test. The test pull-out force is calculated according to formula (1): 4.6.6
G =1. 5[](D d=)
Test pull-out force, N;
Where: G—
[o]——allowable stress of the pipe, N/mm\; D-nominal outer diameter of the pipe, mm;
d-inner diameter of the pipe, mm
Under this pull-out force, for 5 minutes, the specimen is not allowed to produce plastic deformation. After pulling, a water pressure test must be carried out again, and there should be no leakage at the adhesive joint.
4.6.7 Within the working flow range, the pressure loss generated by the pipe fittings should not affect the normal operation of the system. 5 Test method
General requirements
5.1.1. Test equipment, instruments and meters
5.1.1.1 The accuracy of the pressure gauge shall not be lower than Class 0.4. 5.1.1.2 The allowable system error of the flow meter shall not be greater than ±1.5%. 5.1.1.3 The accuracy level of other test equipment, instruments and meters shall meet the accuracy requirements of the test results. 5.1.1.4 Test equipment, instruments and meters shall be inspected and calibrated regularly. 5.1.2 Hydraulic performance test
5.1.2.1 Water supply equipment with adjustable pressure and flow shall be used. 5.1.2.2 The pressure measuring hole should be set at a distance of at least 20 times the pipe diameter from the water flow interference source. The pressure measuring hole should be at right angles to the inner wall of the pipe. The periphery of the hole should be flat and the edges should not be shaved.
5.1.2.3 The pressure gauge should be placed at the same elevation, and the pressure measuring system should be equipped with an exhaust device. Before the test, measure the actual inner diameter and length of the pipeline, and check whether there are air or water leaks in the water supply system, the connection parts of the pipeline system and the measuring system.
5.1.2.5 The test shall be conducted with clean water at room temperature within the range of 0 to 40°C. 5.1.2.6 During the test, the air in the system shall be removed, no bubbles shall be allowed in the pressure measuring tube, the pressure shall be increased slowly, and the flow rate and pressure shall be read or recorded at the same time.
5.2 Performance test
5.2.1 Water pressure test
5.2.1.1 The water pressure test includes the water pressure test of pipes and the water pressure test of fittings. 5.2.1.2 The test pressure is 1.6 times the nominal pressure. After reaching the test pressure, maintain the pressure for 2 minutes and observe whether there is leakage and deformation. 4
5.2.2 Sealing test
JB/T7870-1997
The pipe and fittings shall be matched under the nominal pressure, and the pressure shall be maintained for 5 minutes to observe whether there is leakage at the connection. 5.2.3 Self-leakage test
The tested joint and pipe shall be matched and placed horizontally. After reaching the nominal pressure, the pressure shall be reduced slowly until water flows out from the joint. Then, 2 to 3 pressure values shall be uniformly selected near the pressure point for testing. The self-leakage pressure shall be measured. The self-leakage time and the self-leakage volume of the joint shall be measured at the same time, and the average value shall be taken.
5.2.4 Deflection angle test
Deflect the two connected pipes to the specified angle. After reaching the working pressure, maintain the pressure for 5 minutes and observe whether there is leakage at the connection. 5.2.5 Head loss test along the way
The total length of the test pipeline shall be 100m±10m. 5.2.5.11
The test pipeline shall be straight and placed horizontally. If it is not placed horizontally, the influence of elevation change on pipeline pressure measurement shall be taken into account. 5.2.5.2
The test flow rate shall be uniformly selected from 10 flow rates within the flow rate range corresponding to the economic flow rate of the test pipeline and tested in sequence. 5.2. 5. 3
Test the pressure at both ends of the pipeline, calculate and convert it into the head loss AH1eo along the pipeline per 100 meters: 5. 2. 5. 4
Wherein:
Head loss along the pipeline is calculated according to formula (2):
Head loss along the pipeline, m,
Friction coefficient;
Pipe length, m;
Flow rate, m/h,
Inner diameter of the pipeline, mm;
Flow rate index;
Pipe diameter index.
The significance test results are given at the same time.
5.2.6 Multi-port coefficient test
5.2.6.1Measure and calculate the head loss △H100 along the pipeline per 100 meters according to the provisions of 5.2.5. (2)
5.2.6.2 Under the same flow rate, measure and calculate the head loss AH100 multi-port along the 100-meter pipeline when multiple outlets are used according to 5.2.5. The distance between the orifices should be equal during measurement.
5.2.6.3 The multi-port coefficient is calculated according to formula (3): Where: F multi-port coefficient.
5.2.7 Local head loss test
Perform according to the provisions of Appendix B (Appendix to the standard). 5.2.8 Tensile test
Perform according to the provisions of GB228.
5.2.9 Flattening test
Perform according to the provisions of GB246.
5.2.10 Expansion test
Perform according to the provisions of GB242.
5.2.11 Galvanized layer test
AH100 multi
(3)
Coating weight or thickness determination (choose one: coating weight is determined by the antimony chloride method specified in GB3091; coating thickness 5.2. 11.1
directly measured by a magnetic thickness gauge.
JB/T7870-1997
5.2.11.2 Uniformity test: Determined by the copper sulfate immersion method specified in GB3091. 5.2.11.3 Adhesion test: According to the provisions of Appendix A, choose one test method. 5.3 Operation test
The operation test mainly evaluates the reliability and adaptability of metal thin-walled pipes and pipe fittings. The test should be carried out in the field. 5.3.1
The operation test time shall not be less than 50 0h.
The test should be carried out within the working pressure range. 5.3.3
The main dimensions of the pipes and fittings should be measured before and after the test, and records should be kept. 5.3.4
During the test, if the main parts are damaged, the parts should be replaced and the test should be repeated. The damaged parts should be analyzed, the causes should be found out, and records should be kept.
During the test, someone should be on duty, and maintenance should be carried out according to the instructions, and the test should be recorded. 5.3.6
5.4 Test report
The test report shall at least include the following contents: a) Test purpose;
b) Test location and overview;
c) Technical characteristics of the tested tubes and fittings;
d) Test device system diagram;
e) Specifications and accuracy of test instruments and equipment;
f) Test data;
g) Analysis of test results;
h) Test conclusion,
i) Test personnel and test time.
Inspection rules
Inspection is divided into factory inspection and type inspection.
6.1 Factory inspection
6.1.1 All metal thin-walled tubes and fittings shall be inspected by the quality inspection department of the manufacturer in accordance with this standard, and can only be shipped after the quality certificate is issued after passing the inspection.
6.1.2 Inspection items
6.1.2.1 Thin-walled metal tubes
a) Dimensions (fixed length, wall thickness, outer diameter) and deviations: b) Roundness;
c) Straightness;
d) Inner and outer surface quality;
e) End surface quality;
f) Galvanizing layer quality (or thickness);
g) Galvanizing layer uniformity;
h) Galvanizing layer bonding strength:
i) Water pressure resistance test;
j) Tensile strength test;
k) Expansion test;
1) Flattening test.
6.1.2.2 Pipe fittings
a) Quality of connection parts;
JB/T7870-1997
b) Quality of inner and outer surfaces of castings, welded parts, stamping parts, rubber seals, etc.; c) Quality (or thickness) of galvanized layer;
d) Uniformity of galvanized layer;
e) Adhesion of galvanized layer;
f) Quality of paint;
g) Water pressure resistance test;
h) Sealing performance:
i) Deflection angle test;
j) Self-discharge performance;
k) Vacuum test;
1) Pull-out resistance test.
6.1.3 Random sampling shall be carried out from the inspection batch according to the provisions of GB2828. It is recommended to adopt a normal inspection sampling plan, with the inspection level being the general inspection level I and the qualified quality level (AQL) being 4.0. The sampling inspection plan can also be determined by negotiation between the supply and demand parties. 6.2 Type inspection
6.2.1 Type inspection should be carried out in one of the following situations: a) When a new product or old product is transferred to a factory for trial production and identification; b) After formal production, if there are major changes in structure, materials, and processes that may affect product performance; c) When the product is resumed after a long period of suspension; d) For batch-produced products, in order to understand the stability of product quality, periodic inspection is carried out; e) When the factory inspection results are significantly different from the last type inspection: f) When the national quality supervision agency proposes a type inspection requirement. 6.2.2 The inspection items should include all technical requirements specified in this standard. 6.2.3 The sampling inspection and judgment and disposal rules for type inspection should comply with the provisions of GB2828. It is recommended to adopt a normal inspection sampling plan. The inspection batch should meet the sample size of at least 2, the inspection level is the special inspection level S-1, and the acceptable quality level (AQL) is 6.5.7 Marking, packaging, transportation and storage
7.1 Metal thin-walled tubes
7.1.1 The marking and packaging of galvanized thin-walled steel tubes shall comply with the provisions of GB2102, and the marking and packaging of thin-walled aluminum (aluminum alloy) tubes shall refer to the provisions of GB2102.
7.1.2 During transportation and storage, galvanized thin-walled steel tubes and thin-walled aluminum (aluminum alloy) tubes should avoid contact with corrosive media and mechanical damage.
7.2 Pipe fittings
7.2.1 Each pipe fitting product should have clear and durable markings, which should include the following: a) manufacturer name or registered trademark;
b) product name, model, specification;
c) factory number and date.
7.2.2 The products leaving the factory should be packed in suitable packaging under conditions suitable for transportation and loading and unloading and to ensure that the products are intact, and should comply with the relevant regulations of the transportation department.
7.2.3 The appearance of the packaging should have obvious signs, including: a) the recipient unit and address;
b) the manufacturer's name;
c) the product name, specification, model, quantity; d) gross weight, overall dimensions (length × width × height). 7
The following documents should be attached to the products when leaving the factory:
a) product quality inspection certificate;
b) product instruction manual;
c) packing list.
JB/T7870-1997
During transportation and storage, pipe fittings should avoid contact with corrosive media and mechanical damage. When pipe fittings are stored for a long time, they should be neatly placed in a ventilated and dry warehouse. When storing rubber seals, they should be coated with talcum powder and placed on a rack. They should not be close to heating elements and should be kept away from direct sunlight. Bending test
JB/T7870-1997
Appendix A
Appendix to the standard)
Galvanized layer bonding test
Cut the sample and flatten it. Clamp it in a vise and bend it repeatedly until the substrate breaks. Observe whether the coating peels off or falls off. A2
Chain knife test
File the edge of the sample with a coarse file. The file should be 45° to the surface of the sample. File from the substrate to the coating. Observe whether the coating peels off or falls off.
Hammer test
Strike with a 250g flat-angle round fitter's hammer to observe whether the coating falls off or cracks. Scratch test
Use a sharp knife to scratch the sample in a crisscross pattern until it reaches the base metal. The number of scratches and the distance between scratches are not limited. Observe whether the coating peels off or falls off at the intersection of the scratches.
Heating test
Heat the plated part to 180-200℃, keep it warm for 0.5-1h, and then cool it in the air to observe whether the coating protrudes or falls off. 91 The marking and packaging of galvanized thin-walled steel pipes shall comply with the provisions of GB2102, and the marking and packaging of thin-walled aluminum (aluminum alloy) pipes shall refer to the provisions of GB2102.
7.1.2 During transportation and storage, galvanized thin-walled steel pipes and thin-walled aluminum (aluminum alloy) pipes should avoid contact with corrosive media and mechanical damage.
7.2 Pipe fittings
7.2.1 Each pipe fitting product shall have clear and durable markings, which shall include the following: a) manufacturer name or registered trademark;
b) product name, model, specification;
c) factory number and date.
7.2.2 Ex-factory products shall be packaged in suitable conditions for transportation and loading and unloading and to ensure that the product is intact, and shall comply with the relevant regulations of the transportation department.
7.2.3 The packaging should have obvious signs on the outside, including: a) the recipient unit and address;
b) the manufacturer's name;
c) the product name, specification, model, quantity; d) gross weight, overall dimensions (length × width × height). 7
The following documents should be attached to the product when it leaves the factory:
a) product quality inspection certificate;
b) product instruction manual;
c) packing list.
JB/T7870-1997
During transportation and storage, pipe fittings should avoid contact with corrosive media and mechanical damage. When pipe fittings are stored for a long time, they should be neatly placed in a ventilated and dry warehouse. When storing rubber seals, they should be coated with talcum powder and placed on a shelf. They should not be close to heating elements and should be avoided from direct sunlight. Bending test
JB/T7870-1997
Appendix A
Appendix of the standard)
Galvanized layer bonding test
Cut the sample and flatten it. Bend it repeatedly in a vise until the substrate breaks. Observe whether the coating peels off or falls off. A2
Chain knife test
File the edge of the sample with a coarse file. The file is 45° to the surface of the sample. File from the substrate to the coating. Observe whether the coating peels off or falls off.
Hammer test
Hit with a 250g flat-angle round fitter's hammer to observe whether the coating falls off or cracks. Scratch test
Use a sharp knife to scratch the sample in a criss-cross pattern until it reaches the substrate metal. The number of scratches and the distance between scratches are not limited. Observe whether the coating peels off or falls off at the intersection of the scratches.
Heating test
Heat the plated part to 180-200℃, keep it at this temperature for 0.5-1h, then cool it in air and observe whether the plated layer has protrusions or falls off.1 The marking and packaging of galvanized thin-walled steel pipes shall comply with the provisions of GB2102, and the marking and packaging of thin-walled aluminum (aluminum alloy) pipes shall refer to the provisions of GB2102.
7.1.2 During transportation and storage, galvanized thin-walled steel pipes and thin-walled aluminum (aluminum alloy) pipes should avoid contact with corrosive media and mechanical damage.
7.2 Pipe fittings
7.2.1 Each pipe fitting product shall have clear and durable markings, which shall include the following: a) manufacturer name or registered trademark;
b) product name, model, specification;
c) factory number and date.
7.2.2 Ex-factory products shall be packaged in suitable conditions for transportation and loading and unloading and to ensure that the product is intact, and shall comply with the relevant regulations of the transportation department.
7.2.3 The packaging should have obvious signs on the outside, including: a) the recipient unit and address;
b) the manufacturer's name;
c) the product name, specification, model, quantity; d) gross weight, overall dimensions (length × width × height). 7
The following documents should be attached to the product when it leaves the factory:
a) product quality inspection certificate;
b) product instruction manual;
c) packing list.
JB/T7870-1997
During transportation and storage, pipe fittings should avoid contact with corrosive media and mechanical damage. When pipe fittings are stored for a long time, they should be neatly placed in a ventilated and dry warehouse. When storing rubber seals, they should be coated with talcum powder and placed on a shelf. They should not be close to heating elements and should be avoided from direct sunlight. Bending test
JB/T7870-1997
Appendix A
Appendix of the standard)
Galvanized layer bonding test
Cut the sample and flatten it. Bend it repeatedly in a vise until the substrate breaks. Observe whether the coating peels off or falls off. A2
Chain knife test
File the edge of the sample with a coarse file. The file is 45° to the surface of the sample. File from the substrate to the coating. Observe whether the coating peels off or falls off.
Hammer test
Hit with a 250g flat-angle round fitter's hammer to observe whether the coating falls off or cracks. Scratch test
Use a sharp knife to scratch the sample in a criss-cross pattern until it reaches the substrate metal. The number of scratches and the distance between scratches are not limited. Observe whether the coating peels off or falls off at the intersection of the scratches.
Heating test
Heat the plated part to 180-200℃, keep it at this temperature for 0.5-1h, then cool it in air and observe whether the plated layer has protrusions or falls off.
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