1. Spray painting construction procedures: Manually remove oil stains and welding slag burrs on the pipe wall → sandblast and rust removal Sa2.5 level/Ra60-100μm → spray paint according to the drawing requirements → Quality inspection → Acceptance.
2. Spray painting construction process requirements: For spray painting construction, the ambient temperature should be 10-30°C, the relative air humidity should not be greater than 85%, the surface temperature of the coated base metal should be 3°C higher than the dew point, and when the substrate temperature is higher than 60°C, Painting is not allowed.
3. Surface pretreatment of large-diameter internal and external plastic-coated steel pipes:
1) Before coating the steel surface, perform surface pretreatment. Before pretreatment, welding slag, burrs, grease, and other contaminants on the steel surface should be removed. The surface treatment adopts mechanical shot peening to remove rust, and the rust removal level reaches the requirements of the Sa2.5 level.
2) After de-rusting the steel pipe, it should be blown with dry compressed air, or the dust should be removed with a vacuum cleaner. If the surface of the steel pipe is found to be contaminated or rusted before painting, it should be reprocessed to the original rust removal level. If you accidentally touch the cleaned surface with your hands, clean the surface of the steel pipe with solvent immediately.
3) The surface of the steel after rust removal should be painted as soon as possible. Generally, it should be painted within 4 hours. On sunny days and under good weather conditions, the time should not exceed 12 hours.
4. Spray paint coating
1) The coating operation of large-diameter internal and external plastic-coated steel pipes should be carried out in a clean environment to avoid contamination of the wet coating by dust, etc.
2) Before application, process testing should be carried out according to the regulations of the paint manufacturer.
3) The use of coating materials should be carried out according to the manufacturer’s instructions. The types of coating materials as well as the number of layers, thickness, intervals, and preparation methods should be strictly implemented.
4) Before ingredients are mixed, components A and B should be thoroughly stirred evenly, filtered through a 60-80 mesh sieve, and allowed to mature for 30 minutes before spraying can be carried out.
5) For edges, corners, welds, cuts, and other parts, before painting, a layer of paint should be painted manually, and then a large area of paint should be painted to ensure the thickness of the paint film on the protruding parts.
6) When constructing at temperatures above 30°C, to prevent the paint from curing too quickly, about 5% of special diluent can be added to dilute the paint.
7) When spraying primer and topcoat, a wet film thickness gauge should always be used to measure the wet film thickness of the paint and control the wet film thickness of each paint coat.
8) The sprayed steel pipe should be stored carefully to protect the coating from damage and prevent the harmful effects of high temperature, scorching heat, and adverse weather conditions.
9). A 200mm range is reserved on both sides of the circumferential seam of each large-diameter internal and external plastic-coated steel pipe. When coating the weld, it will not hurt the quality of the weld. The inorganic zinc-rich workshop primer is 40-75 μm to avoid beveling. rust. After the circumferential seam is welded on site, the weld area will be de-rusted a second time to meet the specified requirements, and then the paint will be painted according to the design requirements to reach the specified thickness.
Post time: Apr-07-2024