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GB/T 23257-2017: Polyethylene coating for buried steel pipeline
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Basic data | Standard ID | GB/T 23257-2017 (GB/T23257-2017) | | Description (Translated English) | Polyethylene coating for buried steel pipeline | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | E98 | | Classification of International Standard | 75.200 | | Word Count Estimation | 41,477 | | Date of Issue | 2017-05-12 | | Date of Implementation | 2017-12-01 | | Older Standard (superseded by this standard) | GB/T 23257-2009 | | Quoted Standard | GB/T 1040.2; GB/T 1408.1; GB/T 1410; GB/T 1633; GB/T 1725; GB/T 1842; GB/T 3682; GB/T 4472; GB/T 5470; GB 6514; GB/T 6554; GB/T 7124; GB 7692; GB/T 8923.1; GB/T 13021; GB/T 15332; GB/T 18570.3; GB/T 18570.9; GB/T 50087; GB 50369 | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This standard specifies the minimum technical requirements for steel pipe extruded polyethylene coating and radiation crosslinked polyethylene heat shrinkable tape (sets). This standard is applicable to the design, production and inspection of extruded polyethylene anticorrosive coatings for buried steel pipes, and the design, construction and inspection of the site filling. Other laying of the pipe in the form of extruded polyethylene coating can refer to the implementation. Extruded polyethylene coating can be divided into the highest design temperature does not exceed 60 �� under normal temperature (N) and the maximum design temperature does not exceed 80 �� high temperature type (H) two categories. | GB/T 23257-2017: Polyethylene coating for buried steel pipeline---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Polyethylene coating for buried steel pipeline
ICS 75.200
E98
National Standards of People's Republic of China
Replace GB/T 23257-2009
Buried steel pipeline polyethylene anti-corrosion layer
Released on.2017-05-12
2017-12-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Administration issued
Content
Foreword III
1 Scope 1
2 Normative references 1
3 Terms and Definitions 1
4 anti-corrosion layer structure 2
5 Material 3
5.1 Steel pipe 3
5.2 Anti-corrosion material 3
5.3 Process Evaluation Test 6
6 coating coating 7
7 Quality Inspection 8
8 signs, stacking and handling 9
9 mouth and injury 9
9.1 Filling material 9
9.2 Filling construction preparation 12
9.3 Filling construction 12
9.4 Filling quality inspection 13
9.5 Repair 13
10 Ditch backfill 14
11 Safety, health and environmental protection 14
12 Handling documents 14
Appendix A (Normative) Test Method for Curing Time of Epoxy Powders 15
Appendix B (Normative) Test methods for thermal properties of epoxy powders and their coatings 17
Appendix C (Normative) Method for determination of adhesion of anti-corrosion coatings 20
Appendix D (Normative Appendix) Anti-corrosion layer cathodic disbonding test method 21
Appendix E (Normative Appendix) Anti-corrosion test method for anti-corrosion layer 23
Appendix F (Normative Appendix) Method for determination of oxidation induction period 25
Appendix G (Normative Appendix) Test Method for Determination of Moisture Content of Plastics 26
Appendix H (Normative) Determination of indentation hardness 27
Appendix I (Normative) Test Method for Chemical Resistance of Polyethylene to Chemicals 28
Appendix J (Normative Appendix) Test Method for Ultraviolet Light Aging Resistance of Polyethylene 29
Appendix K (normative appendix) Method for determination of peel strength of anti-corrosion layer 30
Appendix L (normative appendix) Test method for impact strength of anti-corrosion layer 32
Appendix M (Normative) Test method for hot water immersion of polyethylene anti-corrosion layer 33
Appendix N (Normative Appendix) Heat Shrink Tape (Set) Thermal Shock Test Method 34
Appendix O (Normative) Test method for embrittlement temperature of hot melt adhesives 35
Appendix P (normative appendix) Test method for hot water immersion of joint anti-corrosion layer 36
Appendix Q (normative appendix) Test method for heat aging of joint anti-corrosion layer 37
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 23257-2009 "buried steel pipeline polyethylene anti-corrosion layer". Compared with GB/T 23257-2009, mainly
The technical changes are as follows.
--- Adjusted the definition of the highest temperature for the classification of extruded polyethylene anti-corrosion layer, adjusted from "maximum use temperature" to "highest design temperature"
Degree", the temperature value is adjusted from 50 ° C to 60 ° C, 70 ° C adjusted to 80 ° C (see Chapter 1);
--- Added terms and definitions (see Chapter 3);
--- Revised the thermal characteristics of epoxy powder coatings (see Table 2);
--- Revised the tensile performance requirements of polyethylene special materials (see Table 5);
--- Supplementary modification of the performance requirements of polyethylene anti-corrosion layer (see Table 7);
--- Supplementary modification of the performance requirements of heat shrinkable tape joint materials (see Table 11);
--- Increased the requirements for repair preparation and filling process assessment (see 9.2);
--- Revised some of the appendix test methods (see Appendix B, Appendix K);
--- Added appendix test method (see Appendix G, Appendix M, Appendix Q).
This standard was proposed by China National Petroleum Corporation.
This standard is under the jurisdiction of the National Oil and Gas Standardization Technical Committee (SAC/TC355).
This standard is drafted by. China Petroleum Group Engineering Technology Research Institute, China National Petroleum Corporation Ocean Engineering Co., Ltd.
Participated in the drafting of this standard. Baoji Petroleum Pipe Co., Ltd., Daqing Oilfield Engineering Construction Co., Ltd. Tianyu Design Institute.
The main drafters of this standard. Zhang Qibin, Liu Jinxia, He Lian Jianfeng, Wen Hongwei, Chen Shouping, Shi Huihui.
The previous versions of the standards replaced by this standard are.
---GB/T 23257-2009.
Buried steel pipeline polyethylene anti-corrosion layer
1 Scope
This standard specifies the minimum technical requirements for steel pipe extrusion polyethylene anti-corrosion layer and radiation cross-linked polyethylene heat shrinkable tape (set).
This standard is applicable to the design, production and inspection of extruded polyethylene pipe anti-corrosion layer, and the design, construction and on-site filling
test. Other laying forms of extruded polyethylene anti-corrosion coatings can be referred to.
Extrusion polyethylene anti-corrosion layer can be divided into normal temperature type (N) with maximum design temperature not exceeding 60 °C and maximum design temperature not exceeding 80 °C
High temperature type (H) two types.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
Determination of tensile properties of plastics - Part 2. Test conditions for moulding and extruded plastics
GB/T 1408.1 Test methods for electrical strength of insulating materials - Part 1
GB/T 1410 solid insulating material volume resistivity and surface resistivity test method
GB/T 1633 Determination of Vicat softening temperature (VST) of thermoplastics
GB/T 1725 Determination of non-volatile content of paints, varnishes and plastics
GB/T 1842 plastic polyethylene environmental stress cracking test method
GB/T 3682 Thermoplastic melt mass flow rate and melt volume flow rate determination
GB/T 4472 Determination of density and relative density of chemical products
Determination of embrittlement temperature of GB/T 5470 plastic impact method
GB 6514 Painting operation safety regulations Painting process safety and ventilation purification
GB/T 6554 - Resin-based composites for electrical insulation - Part 2. Test method
GB/T 7124 Determination of tensile shear strength of adhesives (rigid materials to rigid materials)
GB 7692 Painting operation safety regulations Pre-painting process safety and ventilation purification
GB/T 8923.1.Determination of surface cleanliness of steels - Part 1 . Uncoated steel
Corrosion grade and treatment grade of the surface of the steel after surface and overall removal of the original coating
GB/T 13021 Determination of carbon black content of polyethylene pipes and fittings (thermal weight loss method)
GB/T 15332 Determination of softening point of hot melt adhesives
GB/T 18570.3.Determination of surface cleanliness of steels -- Part 3.
Surface dust evaluation (pressure sensitive tape method)
GB/T 18570.9 Evaluation of surface cleanliness of steels before coatings -- Part 9.
Conductivity measurement
GB/T 50087 industrial enterprise noise control design specification
GB 50369 Oil and Gas Long Distance Pipeline Engineering Construction and Acceptance Specifications
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Extruded polyethylene coating with extrudedpolyethylenecoating
In the extruder, by heating and pressurizing, the polyethylene is continuously flowed through the extrusion die to form a coating on the pipe.
The coating layer comprises a longitudinal extrusion coating and a lateral wrapping coating.
3.2
Maximum design temperature maximumdesigntemperature
The maximum temperature that the coating may reach during pipeline transportation, handling, construction, and operation.
3.3
Maximum operating temperature maximumoperationtemperature
The highest temperature reached by a pipe or pipeline system during operation.
Note. The maximum operating temperature does not exceed the maximum design temperature.
3.4
Low temperature coated epoxy powder coating lowtemperatureappliedepoxypowdercoating
It is used as the bottom layer of the three-layer polyethylene anti-corrosion layer specified in this standard, and can be applied to epoxy powder coatings below.200 °C.
3.5
Fracture nominal strain nonlineartensilestrainatbreak
Tensile nominal strain corresponding to tensile fracture stress.
3.6
Cohesive failure cohesivefailure
The adhesive layer itself ruptures and adhesive bonds exist on both surfaces of the adherend.
3.7
Interface destruction interfacialfailure
A visually visible damage occurs at the interface between the adhesive layer and the adherend.
4 anti-corrosion layer structure
4.1 Extruded polyethylene anti-corrosion layer is divided into two layers and two layers. The bottom layer of the two-layer structure is an adhesive layer, and the outer layer is a polyethylene layer;
The bottom layer of the three-layer structure is usually an epoxy powder coating, the middle layer is an adhesive layer, and the outer layer is a polyethylene layer. Pipes above DN500 are not suitable
A two-layer polyethylene anti-corrosion layer is used.
4.2 The minimum thickness of the coating shall comply with the requirements of Table 1. The thickness of the anti-corrosion layer at the weld site shall not be less than 80% of the value specified in Table 1. should
According to the pipeline construction environment and operating conditions, select the grade of the anti-corrosion layer.
Table 1 Thickness of anti-corrosion layer
Steel pipe nominal diameter
DN
Epoxy coating a
Mm
Adhesive layer
Mm
Minimum thickness of coating
Mm
Ordinary (G) Enhanced (S)
DN≤100
100 \u003cDN≤250
250 \u003cDN\u003c500
500≤DN< 800
800≤DN≤1200
DN >1200
≥120
≥150
≥170
1.8 2.5
2.0 2.7
2.2 2.9
2.5 3.2
3.0 3.7
3.3 4.2
a Not applicable to two-layer polyethylene anti-corrosion coating.
5 materials
5.1 Steel pipe
5.1.1 Steel pipes shall comply with the current relevant steel pipe standards or technical requirements for ordering, and have a factory certificate.
5.1.2 The visual inspection of steel pipes shall be carried out one by one. Appearance quality should comply with the current relevant standards or technical requirements for ordering, unqualified
Steel pipes should not be coated with an anti-corrosion layer.
5.2 Anti-corrosion material
5.2.1 General regulations
5.2.1.1 Anti-corrosion layer All raw materials shall have the factory quality certificate and inspection report, the instruction manual, the safety data sheet, the factory certificate,
Production date and expiration date. Epoxy powder coating suppliers should provide information such as the thermal characteristics of the product.
5.2.1.2 All kinds of raw materials of anti-corrosion layer should be packed well and should be stored according to the requirements of the product manual.
5.2.1.3 Each brand (type) of epoxy powder coatings, adhesives and special materials for polyethylene shall be recognized by the state before use.
The inspection agency of the certificate shall be tested according to the corresponding performance items specified in 5.2. The performance test results can meet the requirements of the requirements of this standard.
use.
5.2.2 Epoxy powder coating
The properties of epoxy powder coatings and their coatings are to comply with Tables 2 and 3. Coating plant for each production batch (not more than 20t) epoxy
Powder coatings shall be re-examined according to the requirements of Tables 2 and 3 (excluding 65 ° C, 30 d cathodic disbonding). The third item of Table 3 shall be irregular.
Review. When the steel pipe has low temperature coating requirements, it should be coated with epoxy powder coating at low temperature, and the performance should meet the requirements of Table 2 and Table 3.
Table 2 Performance indicators of epoxy powder coatings
Project performance index test method
Particle size distribution
150μm sieve powder ≤3.0
250μm sieve powder ≤0.2
GB/T 6554
Non-volatile content (105 ° C)
≥99.4 GB/T 6554
density
g/cm3
1.30~1.50 and meet the manufacturer's given value ±0.05 GB/T 4472
Gel time
≥12 and meet the manufacturer's given value ±20% GB/T 6554
Curing time
Min
≤3 Appendix A
Thermal characteristics
ΔH
J/g
≥45
Tg2
≥98
Appendix B
Note. The test temperature for the gelation time and curing time of the epoxy powder coating is the coating temperature specified in the product specification. Normal temperature coating powder test when not specified
The test temperature is.200 ° C, and the low temperature coated powder test temperature is lower than.200 ° C.
Table 3 Performance indicators of sintered epoxy coating
Project performance index test method
Adhesion
1 Appendix C
Cathodic disbondment (65 ° C, 48 h)
Mm
≤5 Appendix D
Cathodic disbondment (65 ° C, 30d)
Mm
≤15 Appendix D
Anti-bending (-20 ° C, 2.5 °) No crack Appendix E
Note. The coating thickness of the laboratory sprayed test piece should be 300μm~400μm, and the coating temperature is the temperature specified in the product specification. When not specified, normal temperature coating
The powder application temperature was.200 ° C, and the low temperature coating powder coating temperature was lower than.200 ° C.
5.2.3 Adhesive
The properties of the adhesive shall comply with the requirements of Table 4. The coating factory shall, in accordance with the provisions of Table 4, apply adhesives for each production batch (not exceeding 30 tons).
Conduct a quality re-examination. When the two-layer polyethylene anti-corrosion layer is made of hot-melt adhesive, the appropriate technical performance should be determined according to the engineering requirements.
index.
Table 4 Adhesive performance indicators
Project performance index test method
density
g/cm3
0.920~0.950 GB/T 4472
Melt flow rate (190 ° C, 2.16 kg)
g/10min
≥0.7 GB/T 3682
Vicat softening point (A50, 9.8N)
≥90 GB/T 1633
Embrittlement temperature
≤-50 GB/T 5470
Oxidation induction period (200 ° C)
Min
≥10 Appendix F
Moisture content
≤0.1 Appendix G
Tensile strength a
MPa
≥17 GB/T 1040.2
Fracture nominal strain a
≥600 GB/T 1040.2
a Stretching speed 50mm/min.
5.2.4 Polyethylene
The properties of polyethylene special materials and their pressed sheets shall comply with the requirements of Tables 5 and 6. The coating plant gathers for each production batch (not more than 500t)
Ethylene special materials shall be re-tested for the first 4 items specified in Table 5 and the first 4 items specified in Table 6. If necessary, other properties may be applied.
Carry out a retest.
Table 5 Performance indicators of polyethylene special materials
Project performance index test method
density
g/cm3
0.940~0.960 GB/T 4472
Melt flow rate (190 ° C, 2.16 kg)
g/10min
≥0.15 GB/T 3682
Carbon black content
≥2.0 GB/T 13021
Moisture content
≤0.1 Appendix G
Oxidation induction period (220 ° C)
Min
≥30 Appendix F
Heat aging a (100 ° C, 4800h)
≤35 GB/T 3682
a Heat aging indicator is the rate of change of melt flow rate before and after the test.
Table 6 Compressed sheet performance indicators of polyethylene special materials
Project performance index test method
Tensile yield strength a
MPa
≥15 GB/T 1040.2
Tensile strength a
MPa
≥22 GB/T 1040.2
Fracture nominal strain a
≥600 GB/T 1040.2
Vicat softening point (A50, 9.8N)
≥110 GB/T 1633
Embrittlement temperature
≤-65 GB/T 5470
Electrical strength
MV/m
≥25 GB/T 1408.1
Volume resistivity
Ω·m
≥1×1013 GB/T 1410
Environmental stress cracking resistance (F50)
≥1000 GB/T 1842
Table 6 (continued)
Project performance index test method
Indentation hardness
Mm
(23 ° C)
(60 ° C or 80 ° C) b
≤0.2
≤0.3
Appendix H
Chemical resistant corrosion c (soaked 7d)
10% HCl
10% NaOH
10% NaCl
≥85
≥85
≥85
Appendix I
UV resistant aging c (336h)
≥80 Appendix J
a Stretching speed 50mm/min.
b Normal temperature type, test condition is 60 °C; high temperature type, test condition is 80 °C.
c Resistance to chemical media and UV aging is the tensile strength after the test and the retention of the nominal strain at break.
5.3 Process evaluation test
5.3.1 Coating plant application The selected anti-corrosion layer material shall be subjected to process qualification test on the coating production line, and the performance of the anti-corrosion layer shall be inspected.
Measurement. When the manufacturer of the anti-corrosion layer material or the brand (type) or the diameter of the steel pipe changes or the wall thickness increases, the process qualification test shall be repeated. work
After the art evaluation test is passed, the coating plant shall carry out the coating production of the anti-corrosion layer according to the process parameters determined by the process evaluation test.
5.3.2 The performance of the polyethylene layer and the anti-corrosion layer shall comply with the requirements of Tables 7 and 8.
5.3.2.1 Apply polyethylene layer according to the determined process parameters and perform performance test. The polyethylene layer used for performance testing shall be free of glue and epoxy.
Powder layer, the results should meet the requirements of Table 7.
Table 7 Performance indicators of polyethylene layer
Project performance index test method
Tensile strength a
Axial
MPa
≥20
Circumference
MPa
≥20
Deviation b
≤15
GB/T 1040.2
Fracture nominal strain a
≥600 GB/T 1040.2
Indentation hardness
Mm
(23 ° C)
(60 ° C or 80 ° C) c
≤0.2
≤0.3
Appendix H
Table 7 (continued)
Project performance index test method
Environmental stress cracking resistance (F50)
≥1000 GB/T 1842
Thermal stability d∣ΔMFR∣
≤20 GB/T 3682
a Stretching speed 50mm/min.
b Deviation is the ratio of the difference between axial and circumferential tensile strength to the lower of the two.
c Normal temperature type, test condition is 60 ° C; high temperature type, test condition is 80 ° C.
d The rate of change of melt flow rate before and after extrusion of polyethylene.
5.3.2.2 Except the test piece from the anti-corrosion pipe or the test pipe section coated under the same process conditions to test the overall performance of the anti-corrosion layer, and test
The results should be in accordance with Table 8.
Table 8 Performance indicators of the anti-corrosion layer
project
Performance
Two-layer structure
experiment method
Peel strength
N/cm
(20 °C ± 5 °C)
(60 ° C ± 5 ° C)
≥70
≥35
≥100 (cohesive failure)
≥70 (cohesive failure)
Appendix K
Cathodic disbondment (65 ° C, 48 h)
Mm
≤15 ≤5 Appendix D
Cathodic disbondment (maximum operating temperature, 30d)
Mm
≤25 ≤15 Appendix D
Thermal properties of epoxy powder
Glass transition temperature change value ∣ΔTg∣
- ≤5 Appendix B
Impact strength
J/mm
≥8 Appendix L
Anti-bending (-30 ° C, 2.5 °) Polyethylene without cracking Appendix E
Soaking with hot water (80°C, 48h) The average depth of the warp is ≤2mm and the maximum is ≤3mm. Appendix M
6 coating of anti-corrosion coating
6.1 The surface treatment of steel pipes shall meet the following requirements.
a) Before applying the anti-corrosion layer, remove the grease and dirt on the surface of the steel pipe, and then remove it by spraying (spraying). In progress
Before throwing (spraying) and removing rust, the surface temperature of the steel pipe should not be lower than 3 °C above the dew point temperature. The quality of derusting should reach GB/T 8923.1
The Sa21⁄ grade specified in the specification has an anchor depth of 50μm~90μm. The welding slag and burrs on the surface of the steel pipe should be removed.
b) The dust and abrasive attached to the surface of the steel pipe should be cleaned. The dustiness of the surface of the steel pipe shall not be lower than the provisions of GB/T 18570.3.
Level 2.
c) The steel pipe after the blasting shall be tested for the salt on the surface of the steel pipe according to the method specified in GB/T 18570.9 or other suitable methods.
The content of the salt on the surface of the steel pipe shall not exceed 20 mg/m2. If the surface salt content of the steel pipe exceeds 20 mg/m2, it should be
Treated to acceptable by a suitable method.
d) After the surface treatment of the steel pipe, the surface of the steel pipe shall be protected from moisture, rust or secondary pollution. The surface treated steel pipe should be within 4 hours at the latest.
Coating should be repeated for more than 4 hours or when surface rust or surface contamination occurs.
6.2 When starting the coating of the anti-corrosion layer, first adjust the preheating temperature and the thickness of each layer of the anti-corrosion layer on the production line with the test pipe section, and the parameters are up to
Formal application can be started after the request.
6.3 Apply a non-polluting heat source to the steel pipe to a specified coating temperature. The maximum heating temperature should be lower than the heating temperature limit of the steel pipe.
6.4 Epoxy powder should be evenly applied to the surface of the steel pipe. The use of recycled epoxy powder and its proportion of addition shall be as specified in Tables 2 and 3.
Can be confirmed after inspection.
6.5 Adhesive coating shall be carried out during the epoxy powder gelation process.
6.6 When using the lateral winding process, ensure that the polyethylene of the lap joint and the polyethylene on both sides of the weld are completely rolled and compact without caving, rolling
Avoid damage to the surface of the polyethylene layer.
6.7 After the polyethylene layer is coated, use water to cool the steel pipe to a temperature not higher than 60 ° C, and ensure that the sintered epoxy coating is completely cured.
6.8 After the coating of the anti-corrosion layer is completed, the anti-corrosion layer at the end of the pipe shall be removed. The reserved length of the pipe end should be 100mm~150mm, and it is satisfactory.
Inter-welding and inspection requirements. The end face of the polyethylene layer shall be formed with a chamfer of not more than 30°, and the end of the polyethylene layer shall be kept 10mm~30mm.
Epoxy powder coating.
6.9 When applying a two-layer polyethylene anti-corrosion layer using hot melt adhesive, a detailed and feasible process shall be formulated according to the characteristics of the coating line.
The case is strictly enforced in the coating operation.
7 Quality inspection
7.1 The quality inspection of steel pipe surface treatment shall meet the following requirements.
a) The steel pipe after throwing (spraying) and rusting shall be tested on the surface derusting level by root, using the corresponding photo or standard in GB/T 8923.1
For visual comparison of the board, the surface derusting quality should meet the Sa21⁄ level requirements; the surface anchor depth should be per shift (not more than 12h).
Less measurement twice, each time measuring two steel pipes, should be measured by roughness tester or anchor depth test paper, the anchor depth should be up to
To 50μm~90μm; the surface temperature of the steel pipe before surface treatment should be monitored, and the surface temperature of the steel pipe should not be lower than the dew point temperature.
Above 3 °C.
b) The surface dust degree of the steel pipe shall be tested at least twice per shift (not exceeding 12h), and two steel pipes shall be tested each time. Should be in accordance with GB/T 18570.3
The specified method is used to evaluate the surface dustiness, and the surface dust degree should be no less than 2 grades.
c) Each batch of steel pipes entering the plant shall be tested at least on the surface of the two steel pipes after surface treatment. Steel pipes are stacked or coated by sea, seaside
When the construction site is in the saline-alkali zone, the salt content of the surface of the two steel pipes shall be tested at least every shift (not exceeding 12h). according to
The method specified in GB/T 18570.9 or other suitable method for the determination of salt content on the surface of steel pipes, the salt content on the surface of steel pipes shall not
More than 20mg/m2.
7.2 After derusting, the surface defects of the steel pipe shall be inspected. The surface defects and irregularities (heavy skin, damage, scratches, etc.) of the steel pipe shall not be applied after being repaired.
7.3 During the coating process, the heating temperature of the steel pipe shall be continuously...
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