On the city anti-corrosion coating steel box girder bridges construction technology

Over engineering example, introduced anti-corrosion coating technology steel box girder construction techniques, quality testing standards and results achieved project example, anti-corrosion coating for the steel box to provide technical reference.
    [Key words] city bridge; steel box girder; corrosion; Painting
    [Article ID] 1672-7045 (2011) 12-0064-04 [CLC] U445.7 +3 [Document code] B
    1 Project Overview
    Length of a Bridge bridge 734.5m, single-hole span of 300m, the two inclined steel box arch, curved steel box girder bridge, and the bridge deck boom tilt rods. Among them, the steel box section, a total of 30 full-bridge segments, the maximum weight of 137t, the smallest segment weight 120t. Currently, the steel girder is easily eroded by the external environment, in order to prevent corrosion of steel box girder, to Molybdenum tube normal function of the bridge, the construction of the bridge after its anti-corrosion coating process is necessary. Therefore, in this bridge design, the outer surface of the steel box girder metal coating, paint coating; steel box inside surface using hand-held spray gun for primer finish benefits sweeping sand nap; against corrosion at weld and paint damage sand-blasting, sand blasting preferably Sa2.5 level, paint coating, anti-corrosion design life of ≥ 30 years.
    Two anti-rust coating steel box girder construction points
    2.1 Pre-construction preparation
    2.1.1 rust
    Steel box before painting should be strictly in accordance with "steel surface before painting Rust grades and preparation level" (GB8923) the relevant requirements, the use of throw (spray) pill machinery to rust, so rust grade requirements to Sa2 .5 ~ Sa3 level.
    2.1.2 Control Coating construction environment
    Before the operations, should be strictly controlled coating construction environment. General requirements for steel box girder surface temperature 5 ℃ ~ 35 ℃, relative humidity ≤ 85%, open-air ≤ 85%. All painting is not allowed in the fog, rain environment, the construction of wind speed ≤ 15m / s.
    2.1.3 paint selection and characteristics and requirements
    The choice of paint to prevent corrosion of steel box girder is essential and should be selected based coating technology. Paint and its specific characteristics are shown in Table 1.