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This standard is a revision of the SY/T 0442-2010 Technical standard for internal fusion bonded epoxy coating of steel pipe according to Notice of the national energy administration on issuing the development (revision) plan of the professional standards in energy sector in 2016 (GUONENGKEJI [2016] No.238) (planned number of energy 20160197).
During the revision process of this standard, the preparation team had conducted extensive investigations and summarized the domestic practical experience in the application of internal fusion-bonded epoxy coating for many years. This standard was formed by revising SY/T 0442-2010 on the basis of analysis, research and experimental verification, referring to relevant foreign standards.
This standard comprises of 9 chapters and 5 annexes. The main technical contents include: generals, fabric of internal coating, materials, coating application, quality inspection, repair and re-coating, marks, storage and transportation, field joint coating and completion documents.
The following technical contents have been made with respect to SY/T 0442-2010:
1 The performance requirements for epoxy powder and coatings are revised (see 3.2.3).
2 The requirements for procedure qualification trial are revised (see 4.1).
3 The requirements for coating application are revised (see 4.2).
4 The requirements for quality inspection are revised (see Clause 5).
5 The annex of cathodic disbonding resistance test method for anti-corrosion coating is deleted and replaced by the test method specified in SY/T 0315.
6 The annex of test method for porosity of anti-corrosion coating is deleted and replaced by the test method specified in SY/T 0315.
7 The annex of adhesion test method for anti-corrosion coating is deleted and replaced by the test method specified in SY/T 0315.
The National Energy Administration is in charge of the administration of this standard; the Standardization Committee on Petroleum Engineering is responsible for routine management; CNPC Engineering Technology R&D Company Limited is responsible for the explanation of specific technical contents. In the process of execution of this standard, all relevant organizations are kindly requested to, if found that this standard needs to be modified and supplemented, send opinions and suggestions to CNPC Engineering Technology R&D Company Limited (address: No.40, Jintang Highway, Tanggu, Binhai New Area, Tianjin City; post code: 300451), through combining engineering practices and carefully summarizing experience as well as accumulating documents.
Contents
1 Generals 1
2 Fabric of internal epoxy coating 2
3 Materials 3
3.1 Steel pipe 3
3.2 Epoxy powder 3
4 Coating application 6
4.1 Procedure qualification trial 6
4.2 Coating application 7
5 Quality inspection 9
6 Repair and re-coating 11
6.1 Repair 11
6.2 Re-coating 11
7 Marks, storage and transportation 12
8 Field joint coating 13
9 Completion documents 14
Annex A Test method for curing time of epoxy powder 15
Annex B Test method for thermal characteristics of epoxy powder and coating 17
Annex C Test method for flexibility of coating 20
Annex D Test method for impact resistance of coating 22
Annex E Test method for autoclave 24
Explanation of wording in this standard 26
List of quoted standards 27
1 Generals
1.0.1 For the purpose of regulating the design, production and inspection of internal fusion-bonded epoxy coating, this standard is specially formulated.
1.0.2 This standard is applicable to the design, production and inspection of internal fusion-bonded epoxy coating of steel pipe transporting various oil products, natural gas and oil-gas field production water with operating temperature not exceeding 80℃. When the operating temperature exceeds 80℃, the applicability evaluation at the corresponding operating temperature shall be conducted.
1.0.3 The design, production and inspection of internal fusion-bonded epoxy coating of steel pipe shall meet the requirements of this standard, and the current relevant standards of the nation.
2 Fabric of internal epoxy coating
2.0.1 The internal epoxy coating should have fabric of one-time film formation.
2.0.2 The grade and thickness of the internal epoxy coating shall be selected according to factors such as medium corrosion, operating temperature and pressure. The minimum thickness shall meet the requirements of Table 2.0.2.
Table 2.0.2 Minimum thickness of internal epoxy coating
Coating grade Minimum thickness (μm)
Ordinary grade ≥ 300
Reinforced grade ≥ 500
3 Materials
3.1 Steel pipe
3.1.1 The steel pipe prepared for coating application shall meet the requirements of current relevant standards of the nation or industry or ordering conditions.
3.1.2 The steel pipe manufacturer shall provide the quality certificate and certificate of approval of the steel pipe.
3.1.3 The coating factory shall inspect the appearance of steel pipes piece by piece, and the appearance shall meet the requirements of current standards of the nation or industry related to steel pipe or ordering conditions.
3.2 Epoxy powder
3.2.1 Appropriate epoxy powder shall be selected according to the characteristics of the transporting medium and construction requirements of the pipeline.
3.2.2 The epoxy powder shall have relevant technical documents like product specification, end-of-manufacturing certificate, quality certificate, end-of-manufacturing inspection report and safety data sheet provided by the manufacturer to prove that the epoxy powder meets the requirements of 3.2.3. At the time of delivery, the following contents shall at least be clearly marked on the outer package:
1) Manufacturer name and address.
2) Product name and model.
3) Production date and batch number.
4) Storage temperature and humidity.
5) Validity period, etc.
3.2.3 For each grade (type) of epoxy powder, the epoxy powder manufacturer shall provide the performance inspection report of epoxy powder and laboratory anti-corrosion coating meeting the requirements of Tables 3.2.3-1 and 3.2.3-2, and the report shall be issued by the inspection institution that has passed the national metrology certification.
3.2.4 Epoxy powder shall be sealed and kept dry and clean during shipment and storage. The coating factory shall store the epoxy powder in accordance with the temperature and humidity conditions recommended by the epoxy powder manufacturer.
Table 3.2.3-1 Performance of epoxy powder
No. Test item Quality index Test method
1 Appearance Uniform color, no agglomeration Visual inspection
2 Curing time (min) Complying with the value ±20% given by the powder manufacturer Annex A
3 Thermal characteristics ΔH (J/g) ≥ 45 Annex B
Tg3 (℃) ≥98 and above the operating temperature of 40℃
4 Gelatination time (s) Complying with the value ±20% given by the powder manufacturer GB/T 6554
5 Non-volatile-matter content (105℃) (%) ≥ 99.4 GB/T 6554
6 Mass loss during stoving (230℃, 5 min) (%) ≤1.0 GB/T 21782.7
7 Particle size distribution (%) 150 μm oversize powder ≤3.0
250 μm oversize powder ≤0.2 GB/T 21782.1
8 Density (g/cm3) 1.3~1.5 GB/T 4472
9 Content of magnetic material (%) ≤0.002 JB/T 6570
Table 3.2.3-2 Performance of laboratory epoxy powder coating
No. Test item Quality index Test method
1 Appearance Flat, uniform color, no bubbles, no cracking or shrinkage cavity; slight orange peel pattern is allowed. Visual inspection
2 Thermal characteristics, |△Tg|(℃) ≤5 and in accordance with the characteristics given by the powder manufacturer Annex B
3 Cathodic disbonding (65℃, -1.5V, 48h or 65℃, -3.5V, 24h) (mm) ≤5 SY/T 0315
4 Bonding surface porosity (grade) 1~3 SY/T 0315
5 Section porosity (grade) 1~3 SY/T 0315
6 3° bending resistance (-30℃) No crack Annex C
7 Impact resistance (8J) No leakage point Annex D
8 Adhesion (95℃, 24h) (grade) 1~2 SY/T 0315
9 Adhesion with pull-off method (MPa) ≥ 20 GB/T 5210
10 Abrasion resistance (1kg/1,000r, CS-17 wheel) (mg) ≤35 GB/T 1768
11 Electric strength (MV/m) ≥30 GB/T 1408.1
12 Volume resistivity (Ω·m) ≥1×1013 GB/T 1410
13 Water absorption (80℃, 28d) (%) ≤15 GB/T 1034
14 Hot water soaking resistance (Tmax, 28d) Adhesion 1~2 SY/T 0315
Adhesion with pull-off method (MPa) ≥ 20 GB/T 5210
15 Resistance to salt spray (fog) (1,000h) No bubble, cracking or rust in the anti-corrosion coating GB/T 1771
16 Chemical resistance 10%HCl (90d at normal temperature)
3%NaCl (90d at normal temperature)
10%H2SO4 (90d at normal temperature)
10%NaOH (90d at normal temperature) No bubble, cracking, softening or peeling SY/T 0315
Crude oil (80℃, 90d)
Oilfield sewage (80℃, 90d)
Gasoline (90d at normal temperature)
Kerosene (90d at normal temperature)
Diesel (90d at normal temperature) No bubble, cracking, softening or peeling SY/T 0315
17 High temperature and pressure resistance test (80℃, 6.9MPa, 168h) No bubble, cracking, softening or peeling Annex E
Notes:
1 Laboratory specimens, the thickness of anti-corrosion coating is 300μm~500μm.
2 Film sample used for water absorption test, the thickness should be 500μm±50μm.
3 The test medium and test temperature should be determined according to the working conditions for the corrosion test of chemical medium.
4 Additional test may also be determined according to the working conditions in high temperature and high pressure test conditions.
3.2.5 Before coating application, the epoxy powder used for the first time shall be inspected comprehensively according to corresponding items specified in Tables 3.2.3-1 and 3.2.3-2 of this standard, and the performance shall meet the specified requirements. Then, each batch of epoxy powder (no more than 30t) shall be sampled at least once for inspection. The performance of epoxy powder and its anti-corrosion coating shall be tested according to Items 2, 3, 4, 5, 6, 7, 8, 9 and 10 in Tables 3.2.3-1 and 3.2.3-2 of this standard, and the results shall meet the specified requirements.
4 Coating application
4.1 Procedure qualification trial
4.1.1 Prior to formal coating, the pre-procedure and inspection and trial plan (ITP) for the coating procedure of internal epoxy coating shall be prepared, and coating and inspection tests shall be conducted to confirm the coating quality and form the internal coating which shall meet the required application procedure specification (APS).
4.1.2 The APS shall be prepared according to this standard and engineering requirements, coating parameters recommended by the epoxy powder manufacturer and coating production line conditions. The contents shall cover all links of coating application and control of procedure parameters, and shall at least include the following main contents:
1 Complete information of raw materials, including data sheet of materials, recommended coating procedure and quality control requirements.
2 Surface treatment method and control requirements.
3 Steel pipe heating mode and temperature control requirements.
4 Coating procedure.
5 Inspection and test plan (including inspection contents, test methods, inspection frequency and control requirements).
6 Repair method for defect.
7 Marking regulations.
4.1.3 Coating shall be carried out in accordance with the pre-regulation of application procedure, and the steel pipe, coating production line and epoxy powder used shall be the same as those used in pipeline engineering. The appearance, thickness and leakage point of the steel pipe with internal epoxy coating coated in the procedure qualification trial (PQT) shall be inspected according to the performance items specified in Table 4.1.3, and the results shall meet the requirements.
4.1.4 When the steel pipe specification, coating line, raw material manufacturer or model change, the PQT shall be conducted again.
1 Generals
2 Fabric of internal epoxy coating
3 Materials
3.1 Steel pipe
3.2 Epoxy powder
4 Coating application
4.1 Procedure qualification trial
4.2 Coating application
5 Quality inspection
6 Repair and re-coating
6.1 Repair
6.2 Re-coating
7 Marks, storage and transportation
8 Field joint coating
9 Completion documents
Annex A Test method for curing time of epoxy powder
Annex B Test method for thermal characteristics of epoxy powder and coating
Annex C Test method for flexibility of coating
Annex D Test method for impact resistance of coating
Annex E Test method for autoclave
Explanation of wording in this standard
List of quoted standards
