National pipeline anti-corrosion engineering construction technical plan

1 Foreword

(1) According to the requirements of East China Electric Power Design Institute and other design institutes, in view of the corrosive environment of Iranian power plants, refer to the application of heavy-duty anti-corrosion coatings in nuclear power plants, thermal power plants, Based on the actual use results in hydropower stations and bridges, it is recommended to use high-performance heavy-duty anti-corrosion coatings as a supporting solution for anti-corrosion of steel structure pipelines. (2) In order to prevent corrosion of the steel structure, extend the service life, and ensure the quality of the paint film, the paint coating construction should be carried out in accordance with the requirements of this plan. (3) When carrying out paint coating construction, surface treatment and coating operations should be carried out according to the instructions of the relevant products in this plan to ensure the performance of the anti-corrosion layer.

2 Supporting recommended solutions

(1) The anti-corrosion supporting solutions for buried pipelines (ordinary steel, cast iron) are shown in Table 1.

(2) The anti-corrosion supporting scheme for buried pipelines (galvanized steel) is shown in Table 2.

(3) The anti-corrosion supporting scheme for overhead pipelines without insulation layer (ordinary steel, cast iron) is shown in Table 3.

(4) The anti-corrosion supporting scheme for overhead pipelines without insulation layer (galvanized steel) is shown in Table 4.

(5) The anti-corrosion supporting scheme for overhead pipelines with insulation layer (ordinary steel, cast iron) is shown in Table 5.

(6) The anti-corrosion supporting scheme for overhead pipelines (galvanized steel) with insulation layer is shown in Table 6.

3 Painting requirements

3.1 Surface treatment quality requirements

(1) Use sandblasting to remove rust and oxidation from ordinary steel. Skin and other debris. Surface treatment quality control should reach Sa2 specified in the GB8923 "Steel surface corrosion grade and rust removal grade before coating" standard, with a surface roughness of 35 to 75 μm, and all dust should be removed after sandblasting.

(2) The first coat of paint should be completed on the sandblasted steel within 4 hours. If ET-98 inorganic phosphate long-lasting zinc-rich coating is used, oil and rust removal is generally enough, and it can be applied with slight rust.

(3) Welding parts cannot be painted within 72 hours after welding.

The actual amount of paint used is estimated by the construction unit based on its experience, construction level, construction site and other conditions, and is approximately 1.5 to 1.8 times the theoretical amount (Table 2-Table 6 are the same).

Zinc salts will appear on the surface of the paint film within 3 months. When applying the next coat of paint, all the zinc salts on the surface of the paint film must be removed and polished with dry cloth or sandpaper (Table 2 - Table 6 is the same as this).

If the coating interval exceeds, the surface of the paint film should be roughened with sandpaper before applying the subsequent paint to enhance the interlayer adhesion of the paint film (Table 2-Table 5 and this same).

⑷ The galvanized layer must be removed with light sweep sand blasting to remove dust, oil and other impurities, and then coated with 70-H epoxy iron red anti-corrosion paint.

3.2 Painting environment conditions

The painting environment has a great influence on the quality of the paint film. In order to ensure the painting quality, the following requirements are put forward for the painting environment:

⑴ Open-air painting operations cannot be carried out when exposed to the scorching sun or when there is rain, fog, or snow. It is not suitable for construction when the relative humidity is greater than 85%. The substrate temperature must be 3°C higher than the dew point before construction can be carried out. ET-98 inorganic phosphate long-lasting zinc-rich coating is fine.

⑵ Construction cannot be carried out in summer when there is direct sunlight and the substrate temperature is greater than 60℃. When the temperature is below -5°C in winter, 70-H epoxy iron red anti-corrosion paint, H06-3 epoxy cloud iron anti-rust paint, and ZHL51-2 ultra-thick epoxy asphalt anti-rust paint should not be constructed outdoors in winter.

⑶ Construction cannot be carried out when dust is flying during the painting process and the drying process of the paint film. ET-98 inorganic phosphate long-lasting zinc-rich coating is okay because it dries in 3 minutes.

4 Preparation of paint

⑴ First check whether the type and name of the paint comply with the usage regulations.

⑵After opening the barrel, stir the paint thoroughly to make the sediment evenly mixed.

⑶ Two-component paint must be prepared on site according to the proportions, project quantities, and allowed construction time specified in the instructions, and how much is used.

⑷Preparation method of paint

①Preparation of H06-1 epoxy zinc-rich anti-rust primer

The mixing ratio of A and B is: Group A: Group B Parts = 4:1 (weight ratio)

Method: Add component B into the vat of component A, stir evenly and let it mature for 20 minutes before use.

②H06-3 epoxy mica iron anti-rust paint

The mixing ratio of A and B is: component A: component B = 4:1 (weight ratio) Source: Examination University

Method: Add the component B (curing agent) in the small barrel into the large barrel of component A, stir evenly, and leave it for 20 minutes to mature before use.

③70-H epoxy iron red anti-corrosion coating

The mixing ratio of A and B is: component A: component B = 4:1 (weight ratio). The collector retreats

Method: Add the component B (curing agent) in the small barrel into the large barrel of component A, stir evenly, and leave it for 20 minutes to mature before use.

④ZHL51-2 ultra-thick epoxy asphalt anti-rust paint

The mixing ratio of A and B is: component A: component B = 4:1 (weight ratio)

Method: Add component B (curing agent) into the bucket of component A, stir evenly, and leave it for 20 minutes to mature before use.

⑤Chlorinated rubber topcoat

Method: The chlorinated rubber topcoat is a single can of paint, open the can and stir evenly before use.

5 Construction methods and construction parameters

⑴ Airless high-pressure spraying method can be used, manual brushing or air spraying can also be used. Source: Examination University

⑵ In order to ensure the thickness of the paint film on welds, corners, edges, etc., a pre-coat with a paint brush should be used before large-area painting.

⑶ During painting, the operator should measure the wet film thickness with a wet film thickness gauge at any time to control the paint film thickness.

⑷ When painting, the vertical and horizontal painting method of first up and down and then left and right or first left and right and then up and down should be used to make the paint film smooth and even in thickness.

⑸Please refer to the construction parameters in the instruction manual before construction to master the construction essentials.

⑹ When the cost is higher, ZH polyester modified topcoat or polyurethane topcoat can be used instead of chlorinated rubber topcoat to achieve better anti-corrosion effect.

6 Repair coating of damaged parts of the paint film

If the paint film is mechanically damaged during the painting process and the underlying paint film has been damaged and local rust occurs, the paint film should be repaired by wind. The H06 epoxy zinc-rich anti-rust primer and various supporting coatings can be repaired only after grinding with moving or electric tools to the St2~St3 level specified in the GB8923-88 standard.

7 Inspection

⑴The surface treatment quality shall be inspected according to the color photos in the GB8923-88 national standard.

⑵Appearance inspection of the paint film

Check the surface condition of the paint film with the naked eye. The paint film should be free of pinholes, bubbles, cracks, peeling, sags, missed coatings and other defects.

⑶Control of paint film thickness

Use a paint film thickness gauge to measure the dry film thickness. The thickness of the paint film should be measured after each coat of paint. The paint film must be measured after the painting is completed. Total thickness. Measure one point every 1 to 3 square meters (or otherwise specified). The film thickness value of the measuring points above 90 reaches the specified value, and the film thickness value that does not reach the specified value shall not be lower than 90 of the specified value. Otherwise, it should be re-coated or an additional coat should be applied.

8 Anti-corrosion of temperature-resistant parts of steel structures and pipelines

⑴ For anti-corrosion of temperature-resistant steel structure parts and temperature-resistant parts of pipelines, corresponding high-temperature anti-corrosion primers, topcoats and organic Silicone modified and inorganic modified high temperature resistant coatings.

⑵ Before applying high-temperature resistant coatings, the steel surface must first be sandblasted, shot blasted, oil removed, and rust removed before the primer and topcoat can be applied. In the case of unconditional sandblasting and shot blasting, you can use 88-1 oil-removing, rust-removing and phosphating treatment agent to apply one coat first. After 24 hours, wipe it with a dry cloth and then apply the WEH high-temperature resistant primer. In the plan, after the steel surface is treated like normal paint, it is painted with ET-98 inorganic phosphate long-lasting zinc-rich paint, which can withstand 200~600℃, and then painted with WEH200~300℃, 400℃, 500℃, Two coats of 600℃ high temperature resistant topcoat are required. Generally, one base and two sides of high temperature resistant paint are enough, and the dry film thickness is about 30~90μm. Collectors retreat

⑶ High temperature resistant paint can be used in various colors below 400℃. At around 400~600℃, choose silver gray, medium gray, light gray, black, medium yellow, medium Green etc.

⑷WEH silicone-modified high-temperature resistant paint can be used on galvanized parts and non-metallic parts. The bottom surface is directly painted regardless of the paint. Generally, three coats are enough. See the instructions for details.

9 Fireproof parts of steel structures

The first coat is H06-1 epoxy zinc-rich paint or 70-H epoxy iron red primer, or ET-98 inorganic Phosphate zinc-rich paint. Apply several coats of thin steel structure fire-retardant coatings for the second and above coats. Just apply a few coats according to the fire protection time and requirements.

10 General anti-corrosion requirements

The construction requirements of primer should be as per Table 1 to Table 6 and the intermediate paint remains unchanged. Secondary coat of chlorosulfonated polyethylene topcoat and alkyd topcoat can also be used. Two coats of paint, two coats of high-chlorinated polyphenol topcoat, and two coats of high-chlorinated polyethylene topcoat can be used. Supporting plans can also be designed according to the coating requirements for construction.

11 Other matters

⑴ Paint should be stored in a ventilated, breathable and fire-proof place, away from fire.

⑵ET-98 inorganic phosphate long-lasting zinc-rich coating can improve the anti-corrosion effect by 1-4 times compared with other primer coatings, and it dries quickly, saves construction time, and has long-term anti-corrosion effect indoors and outdoors, etc. Features. When preparing and using component A 1 (liquid) and component B 2 (powder), pour component A into component B powder, mix well, and then add about 15% of ET diluent in time. It can be painted after 20 minutes of curing, 3 minutes of surface drying and 3 hours of solid drying. It plays a conductive role and forms a thin phosphating film on the steel surface to isolate it from the air.

⑶ When using various coatings, pay attention to the shelf life of the product. After the shelf life, re-inspection should be carried out before painting.

⑷When the paint construction is completed, the paint bucket should be covered in time. And use appropriate diluents for hand washing and scrubbing tools.