So far, various types of construction and industrial screws have been designed and manufactured, and in accordance with this need of different world markets and industries, different standards have been provided for different types of bolts and nuts and even washers.
Building screws have certain standards and grades, and in principle, any type of bolts and nuts cannot be used in buildings and structures.
Today, construction screws are widely used in metal structures and buildings. In fact, in comparing concrete and metal structures, one of the advantages of metal structures over concrete frame structures is the use of bolts and nuts. That is why today the sale and purchase of building bolts and nuts in the world is widely used in a variety of metal structures.
Today, three standard screws for metal structures are more widely used than other standards:
• DIN standard (Germany)
• ASTM (American) standard
• ISO (International) Standard
Of course, the ANSI standard may be the fourth standard of construction screws, but mostly many engineers and owners of large and small construction projects in the world, to buy screws and bolts in accordance with one of the above three standards. In particular, the German DIN and ASTM standards, which in our country have been used for many years, screws produced according to these standards.
The most important and well-known standards of construction screws (metal frame structures) are as follows:
• ASTM A325
• ASTM A490
• ASTM A449
• DIN 6914
Due to the sensitivity of the metal structures and the problem of resistance to pressure and weight of the structure, it is necessary to purchase and install construction screws with the appropriate grade. Therefore, in today’s steel structures, most construction screws with the following grades are used:
Of course, we have to emphasize again that this is not a permanent issue and there are exceptions, but mostly high-grade screws are used in the road and construction industry. In heavy metal skeletons of structures, large loads are applied to the screws, so the installed bolts and nuts must have the appropriate class and grade to be able to support the weight of the structure as much as possible.
Therefore, even in this industry, in some cases, the screws are divided into two categories: ordinary screws and resistant screws. The resistance of these screws is measured in megapascals. Ordinary screws usually have a tensile strength of between 400 and 600 megapascals, but high-strength screws often have a tensile strength of between 800 and 1,200 megapascals.
Ordinary building screws are used in cases such as temporary structures, small buildings, trusses and braces, but screws are used in large construction projects such as metal bridges or large buildings.
Connecting high-strength building screws:
Durable screws for steel frame structures that also have a high degree of tensile strength are mainly connected and installed in one of the following two ways:
• Reliable connection
• Friction connection
In the first type (reliability connection), the connection is created by moving and sliding the sheets on the screws. However, due to the type of quality connection, this type of connection is a little lower than the friction type, and in the long run, the probability of damage to the screws is also higher.
The second type or friction connection of construction screws usually uses large and special wrenches such as calibrated wrenches or barbed wrenches. Due to the installation and tightening of the connections using the wrench, it is not possible for the pages to slip and move, and of course, it should be noted that the connection should be cleaned before the connection by bolts and nuts in this type of connection.
Other bolts and nuts used in the building can be mentioned in the facilities section and other parts of the types of rad, anchor bolts and roll bolts. All the mentioned items have a lot of variety in terms of resistance and efficiency.
HV-10.9 screw
TC Bolt
