Some standard content:
1CS 73. 100. 99
Request number: 15516-—2005
Coal Industry Standard of the People's Republic of China
MT/T947—2005
Flameproof high-voltage cable coupling devices for coal mine
Flameproof high-voltage cable coupling devices for coal mine2005-02-14Promulgated
National Development and Reform Commission
2005-06-01Implementation
Normative reference documents
Product classification
Test methods
Inspection rules
Marking, packaging, transportation and storage
MT/T 947-—2005
MT/T947—2005
This standard is proposed by the Science and Technology Development Department of China Coal Industry Association. This standard is under the jurisdiction of the Coal Industry Coal Mine Special Equipment Standardization Technical Committee. This standard was drafted by the Shanghai Branch of the China Coal Research Institute, and the Fushun Branch of the China Coal Research Institute participated in the drafting. The main drafters of this standard are Cao Guanghui, Wang Qikun, Liu Xiaobo, and Chen Hongfei. 1 Scope
Flameproof high-voltage cable connectors for coal mines
MT/T 947-2005
This standard specifies the product classification, requirements, test methods, inspection rules, marking, packaging, transportation and storage of flameproof high-voltage cable connectors for coal mines (hereinafter referred to as connectors). This standard applies to connectors used for cable connection in coal mines with methane or coal dust explosion hazards. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For all dated referenced documents, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this standard. GB/T2423.4—1993 Basic environmental test procedures for electrical and electronic products Test Db: Cyclic damp heat test method (egvIEC68-2-30:1980)
GB383.1—2000 Electrical apparatus for explosive gas atmospheres Part 1: General requirements (egvIEC60079-0:1998) Electrical apparatus for explosive gas atmospheres Part 2: Flameproof type\d\ (eg1EC60079-11990) GB 3836. 2--20001
Electrical apparatus for explosive gas atmospheres Part 3: Increased safety\ (egvIEC60079-7:1990) GB3836.3—2000
GB/T110221999Common technical requirements for standardization of high-voltage switchgear and controlgear (e9VIEC60694:1996) GB/T16927.1—1997High voltage test technology Part 1: General test methods (cqVIEC60-1:1989) MT/T 154.2—-19963
Product model compilation method and management methods for electrical equipment for coal mines 3 Product classification
3.1 Type
The connector is a mining flameproof type.
3.2 Model
The product model compilation method of the connector shall comply with the provisions of MT/T154.2-1996, and its composition and arrangement are as follows:IG
Voltage specification, unit is kilovolt (kV)
Current specification, unit is ampere (A)
-Sequence number
Voltage code
Flameproof code
Connector code
Example; LHG1-200/6 means 6 kV.200 A, the first design of the flameproof high-voltage cable connector for coal mines. 3.3 Basic parameters
Rated voltage: 3.3, 6, 10kV.
Rated current: 200.315, 400, 500A. 1
MT/T 947-2005
4 Requirements
4.1 Structure
The connector structure shall comply with the provisions of GB3836.1-2000, GR3836.2-2000, and GB3836.3-2000. 4.2 Dielectric Strength
The phases of the connector and the phases and the shell shall be subjected to a power frequency withstand voltage test of 50 Hz according to the provisions of Table 1, and no breakdown or flashover shall occur after 1 tuin.
Voltage Level
4.3 Storage Impulse Withstand Voltage
Power Frequency Withstand Voltage Value
Unit:
Lightning Impulse Withstand Voltage Value
The phases of the connector and the phases and the shell shall be subjected to lightning impulse withstand voltage tests for 3 times according to the provisions of Table 1, and no breakdown shall occur. 4.4 Temperature rise
The connector is a continuous working system, and its temperature rise shall comply with the provisions of Table 2. Table 2
Connector materials and fastening methods
1. Head and socket:
Bare copper or copper alloy:
Tin plating: bZxz.net
Silver plating or nickel plating (including thick silver plating and key plate). 2. Conductor joint parts connected by bolts or other equivalent methods: Bare copper, bare copper alloy and bare lead alloy;
Tin plating:
Silver plating (including thick silver plating) or nickel plating.
3. Terminals connected to external conductors by bolts or screws: Bare copper, bare copper alloy and bare aluminum, bare lead alloy: Tin (Tang) or key silver (including thick silver plating). 4.5 Loop resistance
Should meet the design requirements of the product.
4.6 Rated short-time withstand current and rated peak withstand current allowable temperature rise K
The connector shall be tested for rated short-time withstand current and rated peak withstand current according to the provisions of Table 3. After the test, the plug and socket shall not be fused or have other phenomena that hinder normal operation. Table 3
Rated current
Rated short-time withstand current
Rated peak withstand current
4. 7 Static pressure performance of shell
MT/T 947—2005
The shell of the casting and welded parts of the connector shall be subjected to static pressure test according to 15.1.2.1 of G3836.2-2000 after fine processing, and there shall be no obvious deformation that affects the explosion-proof performance.
4. 8 Moisture and heat resistance
The connector shall be able to withstand the alternating damp heat test with a severe level of high temperature + 40℃ and a test period of 21d. The dielectric strength test shall be carried out within 30 minutes after the test, and its dielectric strength shall comply with the provisions of 4.2. 4.9 Explosion-proof performance
The connector shall be able to withstand the shell pressure resistance test and the internal ignition non-explosion test specified in 15.1 and 15.2 of GB3836.2-2000.
4.10 Insertion and extraction force performance
The plug and pull force test shall be carried out between the connector plug and the socket, and the insertion and extraction force shall be 30~-80N. The connector shall be subjected to a temperature rise test after 200 insertion and extraction tests, and its temperature rise shall comply with the provisions of Table 2. 4.11 Oxygen clamping and sealing performance of cable entry device The cable entry device shall be able to withstand the clamping and sealing performance test specified in Appendix D of GB3836.1-2000 and Appendix D of GB3836.2-2000.
4.12 Shell impact resistance
The light metal alloy or cast metal shell shall be able to withstand the impact test with an impact energy of 20J. 4.13 Seal
Seal should be made of single material or composite material, its shape should be suitable for the cable used, and the material should be able to withstand the aging test specified in Appendix D3.3 of GB3836.1-2000.
4.14 Appearance requirements
4.14.1 Cold punched parts should have a smooth surface without defects such as cracks, wrinkles and burrs. 4.14.2 Electroplated parts should have a uniform surface gloss without defects such as spots, blistering, peeling, etc. 4.14.3 For shells made of ferrous metal, after the non-explosion-proof surface is sprayed with paint or surface treated in the finishing shop, the paint film should be flat and glossy without defects such as wrinkles, cracks, and super bubbles.
5 Test method
5.1 Explosion-proof structure inspection
The explosion-proof structure parameters shall be inspected item by item in accordance with GB3836.1-200CGB3836.2--2000.GB3836.3-2000.5.2 Dielectric strength test
After the connector is fully assembled, it shall be placed on the pressure test bench, and the voltage and frequency specified in 4.2 shall be applied between the phases and between the phases and the shell of the connector for 1 min.
5.3 Storage impulse withstand voltage test
Measured in accordance with the provisions of GB/T16927.1-1997. 5.4 Temperature rise test
Measured in accordance with the provisions of 4.4.
5.5 Loop resistance test
Measured in accordance with the provisions of GB/T11022-1999. 5.6 Rated short-time withstand current and rated value withstand current test shall be measured in accordance with GB/T11022-1999. 5.7 Shell static pressure test
Performed in accordance with 15.1.2.1 of GB3836.2-2000. 5.8 Moisture and heat resistance test
Performed in accordance with GB/T2423.4-1993. The severity level shall comply with 4.8.3
MT/T947-2005
5.9 Explosion-proof performance test
Performed in accordance with Chapter 15 of GB 3836.2-2000. 5.10 Insertion and extraction force performance
Performed in accordance with 4.10.
5.11 Cable entry device clamping and sealing performance test shall be carried out in accordance with the provisions of Appendix D of GB3836.1-2000 and Appendix D of GB3836.2-2000. 5. 12 Shell impact resistance test
Carry out in accordance with the provisions of 23.4.3.1 of GB3836.1-2000. 5.13 Sealing diagram aging test
Carry out in accordance with the provisions of Appendix D3.3 of GB3836.1-2000. 5.14 Appearance inspection
Inspect by visual inspection.
6 Inspection rules
6.1 Inspection classification
Product inspection is divided into factory inspection and type inspection, 6.2 Inspection items
Factory inspection and type inspection items are shown in Table 4.
Inspection items
Explosion-proof structure inspection
Dielectric strength test
Lightning impulse withstand voltage test
Temperature rise test
Loop resistance test
Rated short-time withstand current and rated peak withstand current test Shell static pressure test
Condensation heat resistance test
Explosion-proof performance test
Plug-in and pull-out force performance
Cable entry device clamping and sealing performance test Shell impact resistance test
Seal aging test
External inspection
Note: √ means inspection should be carried out; - means no inspection is required6.3 Factory inspection
Factory inspection
Type inspection
6.3.1 Factory inspection shall be carried out one by one according to the inspection items in Table 4. When all factory inspection items meet the requirements of this standard, the factory inspection is considered qualified. If any of the inspection items do not meet the requirements, the inspection should be stopped, the unqualified items should be analyzed, the reasons for the unqualified items should be found out and corrective measures should be taken before the inspection can be continued. If the re-inspection is qualified, it is still judged as qualified; if the re-inspection still does not meet the requirements, it is judged as unqualified.
6.3.2 The connector shall pass the factory inspection according to this standard and be accompanied by a product quality certificate before it can be shipped. 6.4 Type inspection
6.4.1 Type inspection should be carried out in any of the following situations: a)
When new products are trial-produced or old products are transferred to the factory for production: after formal production, if there are major changes in structure, materials, and processes, which may affect product performance; b)
When the type inspection is completed for 5 years;
When the product is discontinued for more than 1 year and then resumed;
When the inspection results are significantly different from the previous type inspection results: e)
f) When the national safety supervision and national quality supervision agencies make requirements. 6.4.2 Sampling and judgment rules
MT/T 947—2005
Products used for type inspection shall be randomly selected from a batch of products that have passed the factory inspection. Two units shall be selected each time. If one of the two samples fails in one inspection item, the batch of products shall be judged to have failed the type inspection; if one of the two samples fails in one inspection item, double the number of samples may be selected and the unqualified items shall be re-inspected. If there are still unqualified items, the batch of products shall be judged to have failed the type inspection. 7 Marking, packaging, transportation and storage
7.1 Marking
7.1.1 Nameplates, notice boards, MA signs and permanent embossed signs "Exd1" shall be firmly set in conspicuous positions on the products, and a grounding symbol shall be set near the grounding bolt.
2 Nameplates, MA signs and warning signs shall be made of chemically resistant materials (such as bronze, yellow steel or stainless steel). 7.1.2
7.1.3 Nameplate content:
Product name and model:
Rated voltage;
Rated current:
Explosion-proof certificate number!
Explosion-proof mark "ExdI\;
Factory date or number;
Manufacturer's name;
Safety mark approval certificate number.
7.1.4 The warning sign content is "It is strictly forbidden to hit with power on".7.2 Packaging
Qualified products should be packed together with technical documents and accessories in plastic film bags, and then packed in suitable packaging boxes.7.2. 1
Pack and tighten.
7.2.2 Technical documents and attachments provided with the product: a)
Product certificate;
b) Product instruction manual;
Packing list;
Accessory bag or box.
7.2.3 The packaging of the product shall meet the requirements of transportation and loading, and shall ensure that the product is not damaged during normal transportation. 7.2.4 Words and logos on the outer surface of the product packaging box Product name and model:
b) Main technical features of the product;
Packing quantity1
d) Net weight and gross weight (kg);
MT/T 947—2005
“Handle with care”, “Keep away from moisture”, “Upwards\” and other shipping operation words or signs: e)
Year and month of production;
Manufacturer name and address, postal code:
Safety sign approval certificate number.
7.3 Transportation
During transportation, the packaging box shall not be overturned, placed upside down, or subjected to strong bumps, vibrations, collisions, or snow and rain. The purchased
products should be stored in a place without rain and snow, with good ventilation conditions, and the air does not contain acid, alkali and other corrosive gases or dust. MT/T947—2005
Coal of the People's Republic of China
Flame-proof high-voltage cable connector for coal mines
MT/1 947--2005
Coal Industry Press
Yaoju, Chao District, Beijing
Website: www, ceiph. coin. rn
Printed by Beijing Geological Printing Factory
Issued by Beijing Publishing House of Xinhua Bookstore
Binding 880mm×1230mm1/16
Printing sheet 374
Number of words 11 Thousand words
Print run 1-30
1st edition in March 2005
2nd printing in May 2005
5020·43
Dunet number 5440
All rights reserved
Price 12.00 yuan
Stop being caught
If this book has any quality problems such as missing pages, reversed pages, or missing pages, our company will be responsible for replacing it2 Inspection items
Factory inspection and type inspection items Table 4.
Inspection items
Explosion-proof structure inspection
Dielectric strength test
Lightning impulse withstand voltage test
Temperature rise test
Loop resistance test
Rated short-time withstand current and rated peak withstand current test Shell static pressure test
Condensation heat resistance test
Explosion-proof performance test
Plug-in and pull-out force performance
Cable entry device clamping and sealing performance test Shell impact resistance test
Seal aging test
External inspection
Note: √ means inspection should be carried out; - means no inspection is required 6.3 Factory inspection
Factory inspection
Type inspection
6.3.1 Factory inspection shall be carried out on each unit according to the inspection items in Table 4. When all factory inspection items meet the requirements of this standard, the factory inspection is considered qualified. If any inspection item does not meet the requirements, the inspection should be stopped, the unqualified items should be analyzed, the reasons for the unqualified items should be found out and corrected, and then the inspection can be continued. If the re-inspection is qualified, it is still judged to be qualified! The inspection is qualified; if the re-inspection still does not meet the requirements, it is judged to be unqualified.
6.3.2 The connector shall pass the factory inspection according to this standard and be accompanied by a product quality certificate before it can be shipped. 6.4 Type inspection
6.4.1 Type inspection should be carried out in any of the following circumstances: a) When a new product is being trial-produced or an old product is being transferred to another factory for production; after formal production, if there are major changes in structure, materials, or processes that may affect product performance; b) When the type inspection has been completed for 5 years; when the product is discontinued for more than 1 year and then resumed; when the inspection result is significantly different from the previous type inspection result; e)
f) When the national safety supervision and national quality supervision agencies make a request. 6.4.2 Sampling and judgment rules
MT/T 947—2005
Products used for type inspection shall be randomly selected from a batch of products that have passed the factory inspection. Two units shall be selected each time. If one of the two samples fails in one inspection item, the batch of products shall be judged to have failed the type inspection; if one of the two samples fails in one inspection item, double the number of samples may be selected and the unqualified items shall be re-inspected. If there are still unqualified items, the batch of products shall be judged to have failed the type inspection. 7 Marking, packaging, transportation and storage
7.1 Marking
7.1.1 Nameplates, notice boards, MA signs and permanent embossed signs "Exd1" shall be firmly set in conspicuous positions on the products, and a grounding symbol shall be set near the grounding bolt.
2 Nameplates, MA signs and warning signs shall be made of chemically resistant materials (such as bronze, yellow steel or stainless steel). 7.1.2
7.1.3 Nameplate content:
Product name and model:
Rated voltage;
Rated current:
Explosion-proof certificate number!
Explosion-proof mark "ExdI\;
Factory date or number;
Manufacturer's name;
Safety mark approval certificate number.
7.1.4 The warning sign content is "It is strictly forbidden to hit with power on".7.2 Packaging
Qualified products should be packed together with technical documents and accessories in plastic film bags, and then packed in suitable packaging boxes.7.2. 1
Pack and tighten.
7.2.2 Technical documents and attachments provided with the product: a)
Product certificate;
b) Product instruction manual;
Packing list;
Accessory bag or box.
7.2.3 The packaging of the product shall meet the requirements of transportation and loading, and shall ensure that the product is not damaged during normal transportation. 7.2.4 Words and logos on the outer surface of the product packaging box Product name and model:
b) Main technical features of the product;
Packing quantity1
d) Net weight and gross weight (kg);
MT/T 947—2005
“Handle with care”, “Keep away from moisture”, “Upwards\” and other shipping operation words or signs: e)
Year and month of production;
Manufacturer name and address, postal code:
Safety sign approval certificate number.
7.3 Transportation
During transportation, the packaging box shall not be overturned, placed upside down, or subjected to strong bumps, vibrations, collisions, or snow and rain. The purchased
products should be stored in a place without rain and snow, with good ventilation conditions, and the air does not contain acid, alkali and other corrosive gases or dust. MT/T947—2005
Coal of the People's Republic of China
Flame-proof high-voltage cable connector for coal mines
MT/1 947--2005
Coal Industry Press
Yaoju, Chao District, Beijing
Website: www, ceiph. coin. rn
Printed by Beijing Geological Printing Factory
Issued by Beijing Publishing House of Xinhua Bookstore
Binding 880mm×1230mm1/16
Printing sheet 374
Number of words 11 Thousand words
Print run 1-30
1st edition in March 2005
2nd printing in May 2005
5020·43
Dunet number 5440
All rights reserved
Price 12.00 yuan
Stop being caught
If this book has any quality problems such as missing pages, reversed pages, or missing pages, our company will be responsible for replacing it2 Inspection items
Factory inspection and type inspection items Table 4.
Inspection items
Explosion-proof structure inspection
Dielectric strength test
Lightning impulse withstand voltage test
Temperature rise test
Loop resistance test
Rated short-time withstand current and rated peak withstand current test Shell static pressure test
Condensation heat resistance test
Explosion-proof performance test
Plug-in and pull-out force performance
Cable entry device clamping and sealing performance test Shell impact resistance test
Seal aging test
External inspection
Note: √ means inspection should be carried out; - means no inspection is required 6.3 Factory inspection
Factory inspection
Type inspection
6.3.1 Factory inspection shall be carried out on each unit according to the inspection items in Table 4. When all factory inspection items meet the requirements of this standard, the factory inspection is considered qualified. If any inspection item does not meet the requirements, the inspection should be stopped, the unqualified items should be analyzed, the reasons for the unqualified items should be found out and corrected, and then the inspection can be continued. If the re-inspection is qualified, it is still judged to be qualified! The inspection is qualified; if the re-inspection still does not meet the requirements, it is judged to be unqualified.
6.3.2 The connector shall pass the factory inspection according to this standard and be accompanied by a product quality certificate before it can be shipped. 6.4 Type inspection
6.4.1 Type inspection should be carried out in any of the following circumstances: a) When a new product is being trial-produced or an old product is being transferred to another factory for production; after formal production, if there are major changes in structure, materials, or processes that may affect product performance; b) When the type inspection has been completed for 5 years; when the product is discontinued for more than 1 year and then resumed; when the inspection result is significantly different from the previous type inspection result; e)
f) When the national safety supervision and national quality supervision agencies make a request. 6.4.2 Sampling and judgment rules
MT/T 947—2005
Products used for type inspection shall be randomly selected from a batch of products that have passed the factory inspection. Two units shall be selected each time. If one of the two samples fails in one inspection item, the batch of products shall be judged to have failed the type inspection; if one of the two samples fails in one inspection item, double the number of samples may be selected and the unqualified items shall be re-inspected. If there are still unqualified items, the batch of products shall be judged to have failed the type inspection. 7 Marking, packaging, transportation and storage
7.1 Marking
7.1.1 Nameplates, notice boards, MA signs and permanent embossed signs "Exd1" shall be firmly set in conspicuous positions on the products, and a grounding symbol shall be set near the grounding bolt.
2 Nameplates, MA signs and warning signs shall be made of chemically resistant materials (such as bronze, yellow steel or stainless steel). 7.1.2
7.1.3 Nameplate content:
Product name and model:
Rated voltage;
Rated current:
Explosion-proof certificate number!
Explosion-proof mark "ExdI\;
Factory date or number;
Manufacturer's name;
Safety mark approval certificate number.
7.1.4 The warning sign content is "It is strictly forbidden to hit with power on".7.2 Packaging
Qualified products should be packed together with technical documents and accessories in plastic film bags, and then packed in suitable packaging boxes.7.2. 1
Pack and tighten.
7.2.2 Technical documents and attachments provided with the product: a)
Product certificate;
b) Product instruction manual;
Packing list;
Accessory bag or box.
7.2.3 The packaging of the product shall meet the requirements of transportation and loading, and shall ensure that the product is not damaged during normal transportation. 7.2.4 Words and logos on the outer surface of the product packaging box Product name and model:
b) Main technical features of the product;
Packing quantity1
d) Net weight and gross weight (kg);
MT/T 947—2005
“Handle with care”, “Keep away from moisture”, “Upwards\” and other shipping operation words or signs: e)
Year and month of production;
Manufacturer name and address, postal code:
Safety sign approval certificate number.
7.3 Transportation
During transportation, the packaging box shall not be overturned, placed upside down, or subjected to strong bumps, vibrations, collisions, or snow and rain. The purchased
products should be stored in a place without rain and snow, with good ventilation conditions, and the air does not contain acid, alkali and other corrosive gases or dust. MT/T947—2005
Coal of the People's Republic of China
Flame-proof high-voltage cable connector for coal mines
MT/1 947--2005
Coal Industry Press
Yaoju, Chao District, Beijing
Website: www, ceiph. coin. rn
Printed by Beijing Geological Printing Factory
Issued by Beijing Publishing House of Xinhua Bookstore
Binding 880mm×1230mm1/16
Printing sheet 374
Number of words 11 Thousand words
Print run 1-30
1st edition in March 2005
2nd printing in May 2005
5020·43
Dunet number 5440
All rights reserved
Price 12.00 yuan
Stop being caught
If this book has any quality problems such as missing pages, reversed pages, or missing pages, our company will be responsible for replacing it3 The packaging of the product shall meet the requirements of transportation and loading, and shall ensure that the product is not damaged during normal transportation. 7.2.4 Wording and logo on the outer surface of the product packaging box Product name and model:
b) Main technical characteristics of the product;
Packing quantity 1
d) Net weight and gross weight (kg);
MT/T 947—2005
“Handle with care”, “Do not get wet”, “Upwards\” and other shipping operation words or signs: e)
Year and month of production;
Manufacturer name and address, postal code:
Safety sign approval certificate number.
7.3 Transportation
During transportation, the packaging box shall not be overturned, placed upside down, or subjected to strong bumps, vibrations, collisions, and snow and rain. The purchased and stored
products should be stored in a place without rain and snow, with good ventilation conditions, and the air does not contain acid, alkali and other corrosive gases or dust.MT/T947—2005
People's Republic of China Coal
Flameproof high-voltage cable connector for coal mines
MT/1 947--2005
Coal Industry Press
Yaoju, Chao District, Beijing
Website: www, ceiph. coin. rn
Printed by Beijing Geological Printing Factory
Published by Beijing Publishing House of Xinhua Bookstore
Combined edition 880mm×1230mm1/16
Printing sheets 374
Word count 11 thousand words
Print runs 1-30
First edition in March 2005
Second printing in May 2005
5020·43
Dunet number 5440
Owner's rights
Price 12.00 yuan
Stop the problem
If there are any quality problems such as missing pages, reversed pages, or missing pages, our company will replace them3 The packaging of the product shall meet the requirements of transportation and loading, and shall ensure that the product is not damaged during normal transportation. 7.2.4 Wording and logo on the outer surface of the product packaging box Product name and model:
b) Main technical characteristics of the product;
Packing quantity 1
d) Net weight and gross weight (kg);
MT/T 947—2005
“Handle with care”, “Do not get wet”, “Upwards\” and other shipping operation words or signs: e)
Year and month of production;
Manufacturer name and address, postal code:
Safety sign approval certificate number.
7.3 Transportation
During transportation, the packaging box shall not be overturned, placed upside down, or subjected to strong bumps, vibrations, collisions, and snow and rain. The purchased and stored
products should be stored in a place without rain and snow, with good ventilation conditions, and the air does not contain acid, alkali and other corrosive gases or dust.MT/T947—2005
People's Republic of China Coal
Flameproof high-voltage cable connector for coal mines
MT/1 947--2005
Coal Industry Press
Yaoju, Chao District, Beijing
Website: www, ceiph. coin. rn
Printed by Beijing Geological Printing Factory
Published by Beijing Publishing House of Xinhua Bookstore
Combined edition 880mm×1230mm1/16
Printing sheets 374
Word count 11 thousand words
Print runs 1-30
First edition in March 2005
Second printing in May 2005
5020·43
Dunet number 5440
Owner's rights
Price 12.00 yuan
Stop the problem
If there are any quality problems such as missing pages, reversed pages, or missing pages, our company will replace them
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