JB/T 6745-1993 Technical requirements for rubber seals for high voltage bushings
Some standard content:
Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Rubber Seals for High-voltage Bushings 1 Subject Content and Scope of Application
This standard specifies the form, technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of rubber seals for high-voltage bushings (hereinafter referred to as seals).
This standard applies to seals for high-voltage bushings with internal oil filling. 2 Reference Standards
GB/T533
GB1682
GB1690
GB2828
Determination of Tensile Properties of Vulcanized Rubber
Test Method for Shore A Hardness of Rubber
Determination Method for Density of Vulcanized Rubber
Test Method for Brittle Temperature of Vulcanized Rubber
Test Method for Liquid Resistance of Vulcanized Rubber
Batch inspection counting sampling procedure and sampling table (applicable to continuous batch inspection) GB3452.2 O-ring appearance quality inspection standard GB3672
GB5719
GB5720
GB5721
GB5722
GB6031
GB6039
GB7529
GB77 59
GB9865
GB9881
3 Terminology
Dimensional tolerances of solid rubber molded and extruded products Terminology of rubber sealing products
Standard method for testing O-rings
General provisions for marking, packaging and transportation of rubber sealing products General provisions for storage of rubber sealing products
Determination of international hardness of vulcanized rubber (30-85IRHD) Conventional test method Terminology for physical and chemical tests on rubber
General provisions for the appearance quality of molded and extruded rubber products Determination of permanent deformation of vulcanized rubber under constant deformation at room temperature and high temperature Preparation of vulcanized rubber samples and test specimens
General terminology for rubber and rubber products
Except for the terms specified in this chapter, the terms used in this standard are in accordance with the provisions of GB5719, GB6039 and GB9881. 3.1 Hardness
Anti-intrusion properties of vulcanized rubber.
Rubber International Hardness
A measure of rubber hardness. Under certain conditions, a specific indenter is used to first press the sample with a smaller initial pressure and then with a larger final pressure. The difference in the indentation depth under these two pressures is measured within a specified time to obtain the international hardness of the sample. 0 degrees of international hardness indicates that the elastic modulus of the material is 0, and 100 degrees indicates that the elastic modulus of the material is infinite. Shore A Hardness
A measure of rubber hardness. Under certain conditions, the initial indentation depth of the sample pressed into the sample with a specific indenter is the Shore A hardness of the sample. Approved by the Ministry of Machinery Industry on August 21, 1993
Implementation on October 1, 1993
3.2 Tensile Strength
The maximum tensile stress of the sample during the stretching process to fracture. 3.3 Elongation at Break
The elongation of the sample at break.
3.4 Brittle temperature
JB/T6745—93
The lowest temperature at which the sample is impacted under specified low temperature conditions without being damaged. 3.5 Compression set
The remaining deformation after the force causing the compression set is completely removed. 3.6 Oil resistance volume change rate
The volume change percentage of the sample before and after immersion in the specified oil at the specified temperature and time. 3.7 Storage period
The time from the completion of the manufacture of the seal to the time it is put into use. Form
The form of the seal is shown in Table 1. Other types of seals can also be implemented by reference. Table 1 Type of seal
Rectangular seal ring
O-shaped seal
Rectangular seal strip
O-shaped seal strip
, 5 Technical requirements
JB/T6745-93
Continued Table 1
5.1 The use conditions of the seal are: the ambient temperature is -40 to +105℃, the working medium is mainly transformer oil, the external medium can also be air, sulfur hexafluoride gas, the medium gauge pressure is not more than 0.6MPa, the optimal compression is 25%-35%, and it is between the metal accessories and the porcelain or metal accessories when used. The height of the seal exposed to sulfur hexafluoride gas should not exceed 2mm. 5.2 The seal must be made of oil-resistant rubber that can meet the use conditions specified in Article 5.1. 5.3 The seal should be manufactured according to the drawings approved by the prescribed procedures. 5.4 The surface of the seal should be smooth and clean, and no pores, cracks, impurities or bubbles are allowed; the appearance quality of O-shaped seals should comply with the requirements of S grade in GB3452.2. The appearance quality of other types of seals should comply with the requirements of GB7529. Note: In order to ensure the surface roughness requirements of the working surface of the seal, the maximum allowable value of the surface roughness parameter Ra of the manufacturing mold relative to the working surface of the seal is 1.6μm.
The dimensional deviation of the seal should comply with the requirements of M3 grade F in Table 1 of GB3672. 5.5
The physical properties of the seal and the vulcanized rubber used to make it should comply with the requirements of Table 2. 5.6
Table 2 Physical property requirements of seals and vulcanized rubber used in their manufacture Item No.
Hardness (international hardness)
Tensile strength not less than
Elongation at break not less than
Brittle temperature
Not higher than
Compression set
(when compressed to 30% deformation rate in air)
Oil resistance Volume change rate
Note: 1)
Density is not an assessment item.
125%×24h
not more than·%
125cx168h
not more than,%
Resistant to No. 1 standard oil
125c×24h
Resistant to No. 25 transformer oil
125C×24h
For rectangular seals, the hardness can also be determined by the Shore A type carbon test method specified in GB531. Index
-10~+5
Test method
GB6031
GB1682
For thiolated rubber:
According to GB7759;
For seals:
According to GB5720
For vulcanized rubber:
According to GB1690;
For seals:
According to GB5720
6 Test method
JB/T6745-93
6.1 The test specimen is taken from the seal. If it cannot be cut directly from the seal, the same batch of rubber materials used to manufacture the seal can be used to prepare the standard specimen according to GB9865 using the same vulcanization conditions as the seal. 6.2 Physical properties shall be tested according to the test methods specified in Table 2. 6.3 When testing on seals, the test method for O-ring seals shall be in accordance with GB5720, and the test method for rectangular seals can refer to the test method for O-ring seals. However, for the volume change rate test of 25# transformer oil, the test results of each test piece shall be within the range specified in Table 2. The test device for compression permanent deformation is recommended to be in accordance with the provisions of Appendix A (Supplement) of this standard. 6.4 The visual method shall be used for appearance quality inspection under bright natural light. 6.5 The size inspection shall be carried out with a measuring tool with a graduation value of 0.02mm in accordance with the provisions of GB5720. 7 Inspection rules
7.: The seals shall be inspected by the inspection department of the manufacturer, and the manufacturer shall ensure that the seals shipped from the factory meet the requirements of this standard. 7.2 According to the inspection rules and test methods specified in this standard, users have the right to inspect whether the seals meet the requirements of this standard. 7.3 The inspection of seals is divided into individual tests, sampling tests, and type tests. 7.3.1 Individual tests
Seals shall be tested one by one according to the items and procedures specified in Table 3. When the molding or extrusion molding method is adopted, the size can be sampled and tested according to the provisions of Article 7.3.2, but if the sampling fails, it should be tested one by one. Table 3 Seal test items and procedures for each test
Item name
Appearance quality
7.3.2 Sampling test
Test basisWww.bzxZ.net
Article 5.4 of this standard
Article 5.5 of this standard
Test method
Article 6.4 of this standard
Article 6.5 of this standard
7.3.2.1 Seals should be accepted in batches. Seals manufactured with the same formula and the same process method are counted as one batch. The number of sealing rings in each batch should not exceed 1,200. The batch size of sealing strips shall be determined by negotiation between the supply and demand parties. 7.3.2.2 Sampling test After each test is qualified, randomly select the test pieces and conduct the test according to the items and procedures specified in Table 4. The appearance quality, size and hardness inspection adopts secondary piece-count sampling, and the sample size and judgment number are specified in Table 5, and the judgment procedure is in accordance with GB2828; the sample size of compression permanent deformation and the volume change rate of 25# transformer oil resistance inspection is specified in Table 4, and the judgment criteria are specified in Table 5. After the sampling test, even if one test fails, the batch is unqualified. However, if only the appearance quality and size are unqualified, it is allowed to be selected one by one, and it can be shipped after passing the test.
Table 4 Sampling test items and procedures for seals
Item name
Appearance quality
Compression permanent deformation
(125×24h）
Volume change rate of resistance to No. 25 transformer oil
Test basis
Article 5.4 of this standard
Articles 5.3 and 5.5 of this standard
Item 2 of Table 2 of this standard
Item 6 of Table 2 of this standard
Item 7 of Table 2 of this standard
Item 1 and Item 2 are carried out during the acceptance test of the seal user unit. Sampling test data
According to the provisions of Table 5,
Total number of random inspections
5 pieces are selected from each batch
Test method
Article 6.4 of this standard
Article 6.5 of this standard
GB6031 (O type)
GB531 (rectangular type)
GB5720 and Article 6.3 of this standard
91~150
15128 0
281~500
501~1200
7.3.3 Type test
JB/T6745—93
Table 5 Sample size and judgment number of sampling test Sample size
Qualified judgment number
Unqualified judgment number
7.3.3.1, when one of the following situations occurs, all or part of the type test shall be carried out in accordance with the provisions of the technical requirements of this standard. a.
All type tests shall be carried out for the trial production of new products or the finalization and identification of the transfer of old products to the factory; only after formal production, if there are major changes in the structural dimensions, material formula, and process, which may affect the performance of the seal, all or part of the type test shall be carried out;
After the seal is discontinued for a long time (usually three years), when the production is resumed, all type tests shall be carried out; c.
d. During normal production, a type test shall be conducted once a year in accordance with the requirements of Table 2 and a report shall be provided; 7.3.3.2 Type test items and procedures shall be in accordance with the provisions of Table 6. If even one test piece fails to meet any test requirement after the test, the type test shall be deemed unqualified.
Table 6 Type test items and procedures for seals
Item name
Appearance quality
Size
Physical properties
Marking, packaging, transportation, storage
Test basis
Article 5.4 of this standard
Article 5.5 of this standard
All items specified in Table 2 of this standard
Number of test samples
Take 5 test samples for each item
The marking, packaging and transportation of seals shall refer to GB5721, and the storage shall refer to GB5722Test method
Article 6.4 of this standard
Article 6.5 of this standard
Articles 6.1, 6.2 and 6.3 of this standard
8.2 Each batch of seals shall be accompanied by a certificate of conformity and a sampling test report. The certificate of conformity shall indicate: product code, name, batch number, quantity, production unit, manufacturing date, and inspection department seal. 8.3 When the type test is carried out in accordance with Article 7.3.3.1, a type test report shall be provided. 8.4 The seal shall be packed with non-damaging, non-polluting, opaque materials and packed in suitable hard material packaging boxes. 8.5 During transportation, the seal shall not be in contact with corrosive substances, greases, acids, alkalis and other substances that are detrimental to the seal, and shall be avoided from direct sunlight and rain and snow.
8.6 The seal shall be stored in a cool, dry, clean and properly ventilated environment. It is not allowed to be stored together with acids, alkalis, greases, chemicals, organic solvents, etc.
8.7 The seal shall be stored in an environment with a room temperature of -5 to +30℃ and a relative humidity of no more than 80%. It shall not be hung for storage. The stacking height of the package shall not exceed 2m, and shall not be less than 0.3m from the ground, and 1m away from the heat source. 8.8 Under the above conditions, the storage period of the seal is one year. For seals that exceed the storage period, the three properties of hardness, constant compression permanent deformation (125℃×24h) and resistance to volume change rate of 25# transformer oil specified in Table 2 of this standard shall be retested, and they can be used only after they are qualified. A1 The test device is shown in the figure below, and the requirements are as follows: JB/T6745-93
Appendix A
Compression permanent deformation test device
(Supplement)
The compression plate should not be deformed during the test. It is recommended to be made of ordinary carbon steel plate, with the dimensions: a.
Length×width×height=120mm×40mm×10mm; b
The compression surface is required to be flat, and the maximum allowable value of the surface roughness parameter Ra is 3.2μm; the height of the limiter is 70% of the basic size of the specimen thickness or cross-sectional diameter, and the tolerance is +0.05mm. 60,
Figure A1 Test device
Bolt: 2-limiter; 3-
Additional instructions:
This standard is proposed by the National Technical Committee for Standardization of Insulators. Compression plate
This standard is under the jurisdiction of Xi'an Electric Ceramics Research Institute and is entrusted to Xi'an Electric Ceramics Research Institute for interpretation. This standard was drafted by Xi'an High Voltage Electric Ceramics Factory. The main drafters of this standard are Liu Xiaoliang and Yi Yuechu.Article 4
Article 6.5 of this standard
Articles 6.1, 6.2, and 6.3 of this standard
8.2 Each batch of seals shall be accompanied by a certificate of conformity and a sampling test report. The certificate of conformity shall indicate: product code, name, batch number, quantity, production unit, manufacturing date, and inspection department seal of conformity. 8.3 When conducting type tests in accordance with Article 7.3.3.1, a type test report shall be provided. 8.4 The seals shall be packaged with non-damaging, non-polluting, and opaque materials and packed in suitable hard material packaging boxes. 8.5 During transportation, seals shall not be in contact with corrosive substances, greases, acids, alkalis, and other substances that may damage the seals, and shall be avoided from direct sunlight and rain and snow.
8.6 Seals shall be stored in a cool, dry, clean, and properly ventilated environment. They shall not be stored together with acids, alkalis, greases, chemicals, organic solvents, etc.
8.7 Seals should be stored in an environment with a room temperature of -5 to +30°C and a relative humidity of no more than 80%. They should not be hung for storage. The stacking height of packages should not exceed 2m, and they should not be less than 0.3m from the ground and 1m away from heat sources. 8.8 Under the above conditions, the storage period of seals is one year. Seals that exceed the storage period should be retested for the three properties of hardness, constant compression permanent deformation (125°C×24h) and resistance to volume change rate of No. 25 transformer oil specified in Table 2 of this standard. They can only be used after passing the test. A1 test device is shown in the figure below, and the requirements are as follows: JB/T6745-93
Appendix A
Compression permanent deformation test device
(Supplement)
The compression plate should not be deformed during the test. It is recommended to be made of ordinary carbon steel plate with the following dimensions: a.
Length×width×height=120mm×40mm×10mm; b
The compression surface is required to be flat, and the maximum allowable value of the surface roughness parameter Ra is 3.2μm; the height of the limiter is 70% of the basic size of the specimen thickness or cross-sectional diameter, and the tolerance is +0.05mm. 60,
Figure A1 test device
Bolt: 2——limiter; 3-
Additional instructions:
This standard is proposed by the National Technical Committee for Standardization of Insulators. Compression plate
This standard is under the jurisdiction of Xi'an Electric Ceramics Research Institute, and is entrusted to Xi'an Electric Ceramics Research Institute for interpretation. This standard was drafted by Xi'an High Voltage Porcelain Factory. The main drafters of this standard were Liu Xiaoliang and Yi Yuechu.Article 4
Article 6.5 of this standard
Articles 6.1, 6.2, and 6.3 of this standard
8.2 Each batch of seals shall be accompanied by a certificate of conformity and a sampling test report. The certificate of conformity shall indicate: product code, name, batch number, quantity, production unit, manufacturing date, and inspection department seal of conformity. 8.3 When conducting type tests in accordance with Article 7.3.3.1, a type test report shall be provided. 8.4 The seals shall be packaged with non-damaging, non-polluting, and opaque materials and packed in suitable hard material packaging boxes. 8.5 During transportation, seals shall not be in contact with corrosive substances, greases, acids, alkalis, and other substances that may damage the seals, and shall be avoided from direct sunlight and rain and snow.
8.6 Seals shall be stored in a cool, dry, clean, and properly ventilated environment. They shall not be stored together with acids, alkalis, greases, chemicals, organic solvents, etc.
8.7 Seals should be stored in an environment with a room temperature of -5 to +30°C and a relative humidity of no more than 80%. They should not be hung for storage. The stacking height of packages should not exceed 2m, and they should not be less than 0.3m from the ground and 1m away from heat sources. 8.8 Under the above conditions, the storage period of seals is one year. Seals that exceed the storage period should be retested for the three properties of hardness, constant compression permanent deformation (125°C×24h) and resistance to volume change rate of No. 25 transformer oil specified in Table 2 of this standard. They can only be used after passing the test. A1 test device is shown in the figure below, and the requirements are as follows: JB/T6745-93
Appendix A
Compression permanent deformation test device
(Supplement)
The compression plate should not be deformed during the test. It is recommended to be made of ordinary carbon steel plate with the following dimensions: a.
Length×width×height=120mm×40mm×10mm; b
The compression surface is required to be flat, and the maximum allowable value of the surface roughness parameter Ra is 3.2μm; the height of the limiter is 70% of the basic size of the specimen thickness or cross-sectional diameter, and the tolerance is +0.05mm. 60,
Figure A1 test device
Bolt: 2——limiter; 3-
Additional instructions:
This standard is proposed by the National Technical Committee for Standardization of Insulators. Compression plate
This standard is under the jurisdiction of Xi'an Electric Ceramics Research Institute, and is entrusted to Xi'an Electric Ceramics Research Institute for interpretation. This standard was drafted by Xi'an High Voltage Porcelain Factory. The main drafters of this standard were Liu Xiaoliang and Yi Yuechu.
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