Steel structure anti-corrosion tips

Steel structure building is now more mainstream and convenient building method, its convenient and fast, green environmental protection characteristics for the majority of users love, steel structure industry in recent years booming, steel structure building although many advantages, but also have certain disadvantages. Easy rust and corrosion is an important disadvantage of steel structure. Especially in rainy weather, the air is humid and humid, how to do a good job in the anti-corrosion of steel structure? Xirong steel structure construction summarizes many years of construction experience, combined with the theory of professional books, summarizes a series of steel structure anti-corrosion related knowledge for everyone, hoping to help friends in the industry in the future construction process!

The atmospheric environment

has a certain corrosiveness to the steel structure, especially the severe smog in winter, the physical and mechanical properties of the steel structure after corrosion decline, etc., affecting the use function and appearance of the engineering structure, reducing the service life of the project, it should be pointed out that: the composition of corrosive substances contained in the atmospheric environment is different, the content of corrosive substances is different, the relative humidity is different, and the corrosion rate of the steel structure is different; The corrosion resistance of protective materials is also closely related to the composition, concentration and relative humidity of corrosive substances contained in the environment. The anti-corrosion design of steel structure of construction engineering should consider the type of corrosion environment, the corrosion resistance of protective materials and the coating environmental conditions.

At present, various conventional anti-corrosion measures are difficult to ensure 100% protection. Coatings and metal thermal spray coatings can cause small, localized corrosion due to pinholes or mechanical breakage, even during their design life.

1. The form of steel structure components and members has a significant impact on the corrosion rate of the structure or members, according to the point of view of the principle of material concentration, the smaller the ratio of the circumference of the section to the area, the higher the corrosion resistance. The thin-walled steel wall is thin, and slight corrosion has a greater impact on the bearing capacity; The cut surface of the lattice structural members is small, plus the trim strip, the embellishment plate is more, and the surface area is large, which is not conducive to anti-corrosion.

Closed cut member end closure is a corrosion protection requirement. When the member of the closed cut is protected by the hot-dip dipping process, the end of the member should not be closed, and the explosion-proof measures should be taken to ensure safety. If the end is closed and then hot-dip galvanized, it may cause an explosion due to high temperature.

Some tests have shown that the corrosion rate of the T-shaped section composed of two angle bars is twice that of the tube shape or 1.5 times that of ordinary I-beams, and the gap between the two angle steels is difficult to protect, forming a concentrated point of corrosion.

In order to ensure the durability of steel components, there must be certain cross-sectional thickness requirements, and members that are too thin will quickly lose their bearing capacity once corroded. The minimum limits specified in this procedure are determined based on experience in use.

2. Portal rigid frame is a steel structure that has been used more in recent years, it has simple shape, reasonable force, and it is recommended to use hot-rolled H-beam steel under corrosion conditions, because of the overall rolling, flat surface, no weld, can achieve better corrosion resistance. The double-sided continuous weld is adopted, so that the front and back sides of the weld are blocked, and the sealing performance is good.

3, grid structure

can achieve large span space and beautiful shape, in recent years rapid development applied to many industrial and civil buildings, steel pipe cutting surface spherical node is all kinds of grid frame members in the small surface area, good corrosion resistance and easy construction of the space structure type, is also widely used in industrial buildings.

Although the hollow ball node of the welded connection is relatively bulky and difficult to construct, its anti-corrosion performance is good, the bearing capacity is high, and the connection is relatively flexible. Bolted ball joints are not recommended under strong and medium corrosion conditions, because the joints are difficult to maintain tight when the steel pipe is bolted with the ball joint.

As a large-span structural component, corrosion prevention is very important, bolt ball joint treatment and excess bolt hole plugging are important measures to prevent corrosion gas from entering

When different metal materials are in contact, contact reaction will occur, and the corrosion is serious, so isolation measures should be taken at the contact site, such as using silicone rubber pads as isolation layers and adding sealing measures

4. The connection material of the component, such as

welding, bolt gusset plate, etc., its corrosion resistance (including protective measures) should not be lower than the main material to ensure the integrity of the structure, spring, pad diagram (such as anti-loosening washer, toothed pad ring) is easy to produce crevice corrosion.

The steel column foot should be placed on the concrete foundation, it is not allowed to use the practice of steel column inserted into the ground and then wrapped concrete, the steel column forms a cathode and anode above and below ground, and the ambient humidity or water accumulation in the rainy season is serious. In addition, indoor and outdoor floors often accumulate water due to poor drainage, and it is stipulated that the top surface of the steel column foundation should be not less than 300mm higher than the ground, in order to avoid water corrosion at the foot of the column.

Weathering steel, that is,

atmospheric corrosion resistant steel, is to add a small amount of alloying elements to the steel, such as copper, chromium-nickel, etc., so that it forms a dense oxide layer in the industrial atmosphere, that is, a protective layer of the metal matrix, to improve the weathering performance of steel, while maintaining good welding performance of steel.

The above is our Xirong steel structure people through sixteen years of steel structure construction experience summed up, for steel structure projects have a practical reference role, but also hope that people in the industry can continue to summarize the experience and key points of steel structure engineering, in the steel structure industry more and more better.