Code for construction and acceptance
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In 2002, Donghua Company independently developed a patented solvent-free epoxy ceramic coating and its special spraying machine (China patent numbers ZL 02 1 554 18.8 and ZL 02 2 89 182.7) according to the demand of foreign markets. Ductile iron pipes, steel pipes and fittings lined with epoxy ceramics are used more and more at home and abroad, and have been exported to Kuwait, Singapore and fittings in large quantities.
In order to provide users with accurate and complete information, Donghua Company has compiled enterprise standards based on the experience accumulated in coating development, production and construction practice. This standard is a recommended standard for reference and use by relevant design, construction and supervision departments, and only applies to the materials specified in this standard.
The main contents of this standard include: scope, normative reference documents, lining structure and construction technology, materials, internal surface treatment, lining, inspection and repair, hoisting and protection, field repair and joint repair, safety precautions, etc.
Drafters of this standard: Zhang Lian and Zhu Ji.
Donghua Anticorrosion Engineering Co., Ltd. is responsible for the interpretation of this standard.
1 range
This standard specifies the specification for construction and acceptance of steel pipes and fittings with epoxy ceramic lining of 0.4 ~ 0.8 ㎜ sprayed or brushed, and is applicable to the design, construction and acceptance of epoxy ceramic lining of steel pipes and fittings for water (including sewage, reclaimed water and drinking water), natural gas, refined oil and crude oil.
2 normative reference documents
The clauses in the following documents become the clauses of this standard by reference:
GB/T 8923-1988 Rust grade and derusting grade of steel surface before painting
SY/T 0457—2000 Technical Standard for Internal Anticorrosion Coating of Liquid Epoxy Coating for Steel Pipelines
Q/DH 03—2004 Color Epoxy Anticorrosive Coatings
Q/DH 06—2004 Epoxy Curing Agent
Q/DH 07—2004 Epoxy Paint and chlorinated rubber paint Diluent
Q/DH 08—2006 Epoxy Ceramic Coatings
3 lining structure and construction technology
3. 1 Construction environment
The epoxy ceramic lining of steel pipe should be constructed in the environment above 15oC, and the relative air temperature should be lower than 85oC. When working in the open air, construction should be stopped in case of bad weather such as rain, snow, fog and sandstorm.
3.2 lining structure
Thickness of hierarchical structure (micron)
Ordinary iron red primer/epoxy ceramic coating (twice) ≥400
Steel bar iron red primer/epoxy ceramic coating (3 times) ≥600
Note: Epoxy ceramics should be painted at least twice, and the number of times can be increased if users need it.
3.3 lining construction process
Steel pipes and fittings: internal bead grinding-sand blasting and rust removal-primer coating (epoxy iron red primer).
-Pre-coating of beads (epoxy ceramic coating twice)-epoxy ceramic coating (2-3 times)-defect inspection-repair and reinspection-
Qualified tube
4. 1 material variety
Use the following certification materials provided by Donghua Company:
A) epoxy ceramic coating. Two-component solvent-free liquid epoxy coatings, including GH 10 1 type (black) for sewage and reclaimed water pipelines and GH 102 type (white, non-toxic) for drinking water pipelines, meet the technical standards of Donghua Q/DH 08-2006 epoxy ceramic coatings and the petroleum industry standard SY/T 0457.
B) iron oxide red primer. Two-component, solvent-based liquid epoxy coating, the technical performance meets the corresponding requirements of Donghua enterprise standard Q/DH 03-2004 "Color Epoxy Anticorrosive Coatings" and SY/T 0457.
C) epoxy curing agent. The technical performance of Donghua Company 1 curing agent meets the corresponding requirements of Donghua Enterprise Standard Q/DH 06-2004 "Epoxy Curing Agent".
D) diluent. Meet the requirements of Donghua enterprise standard Q/DH 07-2004 "Epoxy Coatings and chlorinated rubber paint Diluents".
4.2 Material dosage
Multiply the anticorrosion area by the following cardinal number to calculate the dosage of various materials. (Note: the paint in the container is not poured clean, and too many ingredients are not used in time, which leads to solidification, scattering loss during painting and rework of unqualified products. Users should increase the material consumption by 5% ~ 10% according to their own construction management level. )
A) iron oxide red primer. Brush once, the thickness is greater than or equal to 50μ m, the dosage is about 0. 1 5/㎡, and Donghua1curing agent 10% ~ 12% is added (less in summer and more in winter).
B) epoxy ceramic coating. According to the coating times, it is estimated that the coating amount of each layer with a thickness of 200μm is about 0.4/㎡, and the amount of pre-coating beads and defect repair is 0.1㎡, with component A and component B accounting for 50% respectively. ..
C) diluent. During construction, it is only used as a tool for washing and brushing, and can be mixed according to 15% ~ 20% of the primer dosage.
5 Internal surface treatment
5. 1 bead mill (note: seamless pipe has no such content)
The inner weld bead is polished by an electric grinder, with the purpose of removing burrs on the weld bead and protruding points on the flash, and ensuring that there are no pinholes on the weld bead after painting.
5.2 sandblasting
A) Spray quartz sand on the inner surface to remove rust until it reaches the Sa2 1/2 grade of GB/T 8923 (equivalent to the nearly white grade of American standard SSPC-SP 10).
B) Purge the inner surface of the pipeline with clean compressed air (after dehydration and degreasing).
C) Primer must be applied before the surface rusts again (at most 8 hours after rust removal).