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    Home > Coatings News > Paints and Coatings Market > What details do I need to pay attention to for anti-corrosion coating of steel pipes?

    What details do I need to pay attention to for anti-corrosion coating of steel pipes?

    • Last Update: 2020-11-20
    • Source: Internet
    • Author: User
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    First, surface pre-treatment
    (1) pressure steel pipe inside and outside the wall metal surface by injection rust removal, in the relatively sealed room for construction. Its rust removal grade conforms to GB8923-88 "pre-coating steel surface rust grade and rust removal grade" standards specified in the grade. The rust removal grade of the metal surface of the outer wall of the buried pipe conforms to the Sa1 grade specified in GB8923-88
    the
    . Surface roughness is in accordance with Article 11.7.2 of the Technical Terms of the Tender Documents.
    (2) For local repair of coating defects can be manual and dynamic rust removal, its surface cleanliness level should reach GB8923 st3 level.
    (3) is a dry and clean, angular steel sand with angular impurities, with a particle size of 0.8 to 1.5mm.
    (4) Surface pre-treatment construction climate conditions requirements:
    a. The relative humidity of the air must not be less than 85%.
    b. The surface temperature of the base metal shall not be lower than 3 degrees C above the dew point.
    c. Under adverse climatic conditions, effective measures, such as covering, heating or importing purified, dry air, are used to meet the requirements of the working environment.
    (5) the compressed air used to spray rust must be treated by a cooling device and an oil-water separator. And regularly clean the oil and water separator.
    (6) Prep work before spraying rust removal:
    a. Defects such as welding slag, welding scars and burrs on metal surfaces should be cleaned up.
    b. Thoroughly clean organic impurities such as grease on the surface of the steel pipe.
    (7) Injection process parameters:
    a. Distance: Nozzle to substate metal surface should maintain a distance of 100 to 300mm.
    b. Angle: The angle between the injection direction and the surface of the substation is 15 to 30 degrees.
    c. Nozzle: When the diameter of the hole is increased by 25% due to wear, it is advisable to replace the nozzle.
    (8) the metal surface of the treated steel pipe must not be touched by hand after the injection treatment has been completed. And use a vacuum cleaner or dry, oil-free compressed air to remove dust and debris from the metal surface of the steel pipe.
    , surface pretreatability inspection
    (1) surface cleanliness and surface roughness assessment, should be in good scattering daylight or light equivalent artificial lighting conditions.
    (2) coating quality inspection in accordance with the construction design drawings and tender documents technical provisions 11.7.4 requirements.
    (3) carefully do a good job of surface pre-treatment quality inspection work, and fill in the quality record.
    3. Steel pipe inner wall coating
    (1) Steel pipe inner wall surface pre-treatment quality assessment should be carried out in a timely manner after coating construction, coating should be completed within 4h, sunny or not too humid weather, coating work should be completed within 8h.
    (2) The inner wall of the steel pipe is coated with self-conserving primers and finishes, and is coated twice with high-pressure airless spraying, with a 24-hour interval between each coating and a dry film thickness of 500 m after the second coating.
    (3) When the relative humidity of the air exceeds 85% and the surface temperature of the base metal is lower than the atmospheric dew point of more than 3 degrees C, no coating construction shall be carried out.
    (4) in strict accordance with the paint manufacturer's instructions, coating construction.
    (5) paint a workshop primer within 200 mm on each side of the mounting ring seam that does not affect the quality of the weld.
    (6) coating, the coating should be carefully maintained, before curing to avoid rain, exposure, trampling, handling should be properly protected.
    (7) the construction site must be dry, clean and well ventilated.
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