The anti-corrosion of the steel pipe is based on the requirements of the drawing, the epoxy coal tar pitch paint is used to wrap the glass cloth, and the anti-corrosion topcoat is applied outside. The construction process of the outer wall:
Pipeline derusting→priming paint→finishing paint→second topcoating→glass cloth wrapping→topcoating→topcoating;
Inner wall construction process: pipe rust removal → primer → top coat → second top coat → third top coat
1. Pipeline de-rusting
Before the primer is applied, the surface of the pipe should be cleaned of grease, ash, rust, and oxide scale. Sandblasting is used to remove rust, and its quality standard reaches Sa2.5 level.
2. After de-rusting the surface of the pipe, apply primer, and the time interval between them should not exceed 8 hours. When applying primer, the base surface should be dry. The primer should be applied evenly and fully without any clots or blisters, and the paint should not be painted within the range of 150-250mm at both ends of the pipe.
3. After the surface of the primer is dry, apply the topcoat and wrap the glass cloth. The time interval between the primer and the topcoat should not exceed 24 hours.
4. Epoxy coal tar pitch paint adopts two-component, normal temperature curing type paint; glass cloth adopts drying, dewaxing, untwisted, edge sealing, medium alkali, and the warp and weft density is 10*12/cm～12*12/ cm glass cloth. Immediately after the topcoat is applied, wrap the glass cloth with a blanking width of 30-40mm, and the overlapping length of the joints should not be less than 100mm, and the overlapping joints of each layer should be staggered. The oil penetration rate of the glass silk cloth shall be above 95%, there shall be no gaps larger than 50mm*50mm, and 150-250mm of stepped stubble shall be left at the end of the pipe.
5. The construction of the pipe interface should be carried out after the welding pressure test is qualified. The old and new anti-corrosion pressure edge should not be less than 50mm, the lap length of the joint should not be less than 100mm, and the stubble joint should be firmly and tightly bonded.
6. Steel pipe outer wall coating mechanism: one bottom and two sides, one cloth and two sides, the total thickness of the dry film is 400µm.
7. Steel pipe inner wall coating mechanism: one bottom and three sides, the total thickness of the dry film is 300µm.
8. After the external anti-corrosion construction is completed, the quality inspection shall be carried out according to the design requirements or the corresponding requirements in Table 4.3.11 in the “Code for Construction and Acceptance of Water Supply and Drainage Pipeline Engineering”.
Post time: Feb-24-2023