The primary and secondary steel structures are sanded and painted according to the requirements of anti-corrosion. The amount of paint is largely related to the thickness of the dry film, and also related to the construction method and coating system (spraying is more expensive than manual brushing), the following The data is the theoretical coating rate (for reference only), and the actual dosage is multiplied by a coefficient of 1.5-1.8:

75 microns thick, about 8.5 square meters per liter;

125 microns thick, about 6.5 square meters per liter;

200 microns thick, about 4 square meters per liter.

It is generally measured in volume units.

There is a theoretical coating rate in the paint manual, that is, how many L paint should be used for 1 square meter of 100um (or 50um, etc.). For example, this number is X%

Then the amount of paint = x%*25000*paint thickness/100

After this result, you multiply it by a loss factor, such as 1.3. Generally this is related to the construction equipment.

The net weight of the weld on the steel structure is about 1.5-2% of that of the steel member. Then lift the electrode based on this. Because it is the net weight, the weight of the electrode is slightly increased. In addition to the weight of the electrode head and the coating, the weight of the electrode is generally 1.8 to 2.2 times.

Steel structure engineering paint consumption and loss coefficient estimation method The theoretical coating rate and actual coating rate calculation formula of the paint is on a completely smooth and flat glass surface without pores, pour one liter of paint to form the specified dry film thickness. The area is called the theoretical spreading rate of the paint.

Theoretical coating rate=solid volume content*10/dry film thickness (micron) (m²/liter)

In actual construction, due to the influence of various factors such as the surface shape of the construction work piece, the required paint film thickness, construction method, worker skills, construction environmental conditions, weather, etc., the actual amount of paint used must be greater than the construction area divided by the theoretical coating. The "theoretical usage" calculated by the distribution rate.

Actual paint usage/theoretical usage (The ratio is defined as the "loss factor" CF.)

The actual amount of engineering paint = construction area / actual coating rate = construction area * CF / theoretical coating rate = theoretical use × CF "loss factor" CF analysis and estimation: the paint loss caused by the surface roughness of the workpiece is sprayed When the surface is painted, the film thickness at the peak of the steel plate should be less than that at the trough. In order to meet the anti-corrosion thickness requirements at the peak (to avoid pitting corrosion), the paint "hidden" in the potholes of the trough is equivalent to being wasted , This is "steel plate roughness consumption loss". The following table shows the paint loss caused by different spraying methods (expressed in dry film thickness):

Paint loss caused by uneven film thickness distribution

After the film thickness reaches or exceeds the specified film thickness during the acceptance of the paint film after construction, the technical service representative, the supervisor or the owner will sign as normal, but the part that does not meet the specified film thickness will be required to recoat, so it will inevitably cause "excessive thickness" loss. The specific factors that lead to uneven distribution of paint film thickness mainly include: worker proficiency, construction environment, simple or complex construction work piece (flat work piece), and construction method (no air spraying, air spraying, brushing, rolling).

Construction waste

 Construction waste refers to the waste of paint that does not reach the surface of the construction work piece and is lost to the surrounding environment or the ground. If there is no air spraying, the loss of paint is about 10-20%, if there is air spraying, the loss of paint is more than 50%, and the loss of rolling is about 5%. When the brush is well controlled, it is relatively less. Bridge spraying in high wind environment can cause more than 100% waste.

Waste of residual paint in the container

After the paint is applied, the average loss of the paint remaining on the inner wall of the paint bucket and the rubber tube is about 5%.

In summary, the paint loss coefficient during construction is mainly caused by the loss of surface roughness of the workpiece, the loss of uneven paint film thickness, the waste of construction, and the waste of residual paint in the container.