Steel structure bolt standards are different from ordinary bolt standards. What are the specific differences? Can it be hot-dip galvanized like ordinary bolts? Let Xiaorui analyze it for you one by one.
First look at its standard. The standard of steel structure bolts is produced according to the national standard GB/T1228. This standard includes two washers and one nut, so the sales of steel structure bolts are based on sets. Other GB/T1229 refers to nuts, and GB/T1230 refers to flat washers. Its strength grade is 10.9, the nut is 10, and the flat washer is also made of reinforced material, which is different from ordinary washers and relatively thicker. Bolts can only be used after quenching and tempering treatment. In the original state, its color is gray, and the HRC hardness is about 35 degrees. The average value should be calculated, and the hardness of each part may be slightly different.
Under the tensile test of steel structure bolts, it can reach 600KN, and the torque is 1250Kn. These requirements are the minimum parameters specified in the national standard, that is to say, in actual testing, it must not be lower than this standard. During installation, the size of the torque is related to the firmness of the installation. If the torque is too large, the thread of the bolt will be screwed. If it is too small, it will become loose again. Therefore, the installation of steel structure bolts must use standard torque. tools to achieve.
We sometimes find broken steel structure bolts on site. After professional analysis, this kind of fracture is not caused by heat treatment, but by the material itself. Under the attack of two factors, the bolts will be prone to breakage. However, this kind of fracture is random, and such quality problems will not occur in a large area. We only need to check carefully once during installation to prevent such phenomena.
So can steel structure bolts be hot-dip galvanized like ordinary bolts?
I want to divide this issue into several points. First, steel structure bolts are high-strength bolts, and high-strength bolts are not recommended for surface treatment, whether it is hot-dip galvanized or cold-dip galvanized. Therefore, in principle, steel structure bolts are not convenient for hot-dip galvanizing. What if the design must be hot-dip galvanized?
In reality, there are indeed many places where hot-dip galvanized steel structural bolts are used, such as the connection of outdoor utility poles. In order to ensure the quality of the steel structure bolts and prevent fractures, the steel structure bolts must undergo a galvanizing treatment when they are hot-dip galvanized. Don’t underestimate this galvanizing, which can effectively achieve the purpose of tempering. Structural bolts are not so prone to brittle fracture, and it can also ensure that the zinc layer on the surface of steel structural bolts does not peel. In summary, steel structural bolts can also be hot-dip galvanized, but be careful and careful during the production process some.
The hot-dip galvanizing of the steel structure nuts used together is also different from the ordinary nuts. When we use hot-dip galvanized steel structure nuts, due to the amount of use, usually no manufacturer will stock up in advance. When there is an order, in order to deliver If the goods are in time, you can only use galvanizing first, and then tap the teeth on the tapping machine. Therefore, the inner teeth of the steel structure nut are not covered with zinc layer, but there is no need to worry about whether it will rust, because the threaded inner hole will Has an anti-rust oil coating.
Steel structure bolts are also called connection pairs, which refer to another torsional shear steel structure. In order to ensure consistent and stable quality of bolts, under normal circumstances, we will use the same batch of materials for several parts in a set of products. Production, heat treatment after production is also completed in the same furnace, in terms of bolt performance level, 10.9 grade is the most suitable for steel structure bolts, and its minimum specification starts from M16 and ends at M30, which is also It is different from other ordinary bolts. The high-strength nut used together has a round platform on one side. When installing, the side of the round platform should face inward. This point needs to be paid attention to. Other installation methods are the same as ordinary bolts.
Steel structure bolts were officially adopted in 1970, and many early industrial plant installations were installed with steel structure bolts. Before entering the country, steel structure bolts were a patented product and could not be directly included in the national standard. Steel structure bolts were needed in many domestic construction fields, but they were limited to patent copyrights, which could only be ignored. In the era of rapid development in our country, due to the deficit of all trade products, coupled with the need for national construction, all such products are used more and more. At the same time, many countries have formulated their own relevant standards. Also according to actual needs, the standard of steel structure bolts has been improved and included in the scope of the national standard, so that the use of steel structure bolts has been fully utilized and realized its maximum value.
When steel structure bolts are remanufactured, the procurement and testing of materials are very strict. Various chemical compositions and torque parameters are used only after an authoritative report is issued by a third-party quality testing agency. Steel structure bolts are installed with silent equipment and tools during construction. Many electric tools have their own power supply, and the early installation of air compressors is basically not used. Because many steel structural bolts are used outdoors, it is not very convenient to connect the power supply of the air compressor, and the installation of the built-in lithium battery is very convenient.
After the material of the steel structure bolt is purchased to the factory, it must first go through a pickling process to clean the residual stains on the surface, and form a phosphating layer on the surface of the material, so that the material itself is not easy to be damaged. , the surface finish of steel structure bolts can meet the requirements. Before the material is put on the machine, the raw material must be spheroidized and drawn. If the material is too hard, it must be annealed. After the steel structure bolt is formed, it will be heat treated and tempered, so as to improve the strength of the steel structure bolt. , and finally the goods can be delivered to the user after being tested and packaged.
The storage of steel structure bolts is different from ordinary bolts. It should be stored in a dry and dust-free warehouse, so as to ensure that when installing steel structure bolts, the nuts and threads can quickly form a vertical state, and the nuts can be easily tightened. There is also a steel structure flat washer used in conjunction with it. The material is the same as the bolt. When working in rainy days, there should be a rainproof measure to install. After the installation is complete, it is best not to rotate and loosen it easily. Although it is not a one-time product, it is best for one-time use.
