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Guide to buying bolts and nuts

One of the important issues that engineers consider in advance for the implementation of construction or industrial projects is the supply of parts or materials. In this regard, screws and nuts have a special place because they have many uses in various industries and in construction matters, and today industrial or construction screws play an important role in the global markets of industrial and construction parts and accessories.

In the past articles or different sections of this website, in order to get to know you, dear readers, as much as possible, regarding the types of parts used in metal connections, such as types of screws, nuts, or washers, including hexagon screws, types of construction screws, We have written HV screws, 8.8 screws and other items in detail, which we hope will be useful for those interested and active in the industry or construction areas.

But the important thing is that when you want to buy and order bolts and nuts, reading the guide for buying bolts and nuts can be very useful for you. Especially for young and inexperienced engineers or managers, this can be critical in some cases.

In the field of buying bolts and nuts for metal connections, you should pay attention to several points:

• Whether the intended bolt is industrial or construction type
• screw grade
• Corresponding nut grade
• Standard bolts
• Size and dimensions of bolts and nuts
• Plating type

Fortunately, we have written about most of the points mentioned in detail in other articles, but briefly and for reminder, we can describe the above as follows:

Bolt type:
It is very important that the bolts and nuts you are looking for are purchased for use in industrial or construction purposes. Despite the similarity of these types of screws and related nuts, it is better to use each of them for their respective purposes.

Guide to buying bolts and nuts

Bolt and nut grade:
The grade or class of bolts and nuts indicates their resistance according to the relevant standard. Currently, among the most important types of screws that are used, we can mention screws with grades 4.8, 5.6, 6.8, 8.8, 10.9, etc., which are widely used in various sectors of the industry as well as in the construction of metal skeleton structures. are used a lot.
As you know, even for the selection and purchase of nuts and washers, it should be done in harmony with it, so that, for example, grade 8 nuts are not used for grade 10.9 screws.

Bolt standard:
Today there are different standards for bolts and nuts. Among the most important and famous standards that we have already introduced to you in other articles, we can mention the DIN standard of Germany, the ASTM standard of the United States and also the ISO standard.

Bolt size:
The dimensions of the screw as well as the length of its thread are very important. As we have explained, in order to use screws, nuts and washers in any project – whether industrial or construction – their grade and size must be appropriate so that the connections are connected to each other in the best possible way and these connecting parts, in the long run maintain their quality.

The plating of bolts and nuts and whether they are galvanized or not is also very important for engineers and project managers to buy. Today, the bolts and nuts offered in their grades may be hot galvanized, cold galvanized, or dichromated.

For consultation and purchase of all kinds of screws and nuts or washers, contact Pars Pishgaman Company. We provide you with the best products.

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Comparison of concrete and metal structures

Both concrete and metal structures have many applications in the construction industry. But it should be seen what is the difference between concrete and metal structures and comparing these two types of structures, in which fields each is more useful, how are their connections made and what are the advantages and disadvantages of each one compared to the other. including important things such as the use or non-use of bolts and nuts in the connections of these structures. In addition to young engineers in fields such as civil engineering, road and construction, and architecture, knowing these details can be useful even for ordinary citizens. Especially those who want to buy a house or newly built apartment units.

Types of structures:
First of all, we must clarify this issue that, contrary to what many people think, structures are basically of two types:

• Natural structure

• Artificial structure

This category does not need to be introduced, but the second type or artificial structures are divided into several categories, including:

• Concrete Structures

• Metal

In the following, we want to compare these two types of structures. Of course, as you know, what is meant by metal or concrete structure is actually their skeleton, and in fact, if we want to deal with this topic according to scientific principles, we should say the comparison of metal skeleton structure and concrete skeleton structure. Another important issue is the use of bolts and nuts in structures. Today, metal structures can be divided into two categories according to the type of connection:

• Bolted metal structure

• Welded metal structure

Both methods are used in metal structures today. This means that when designing and performing calculations for any type of these structures, for some reason, engineers may consider using bolts and nuts or other methods such as welding to connect different parts of these structures.

In the following, in addition to the general comparison of metal (steel) and concrete structures, we will also compare bolt and nut structures and welded structures.

How to choose the right structure:
Metal and concrete structures each have advantages over the other, and most buildings and skyscrapers use one of these two types of structures. However, the selection of the type of structure in the countries of the world by engineers is subject to various conditions, such as:

• climate

• Existing infrastructure and space

• Height and span of columns

• The type of soil in the area

• Construction cost

• The structure’s resistance to earthquakes

• Stability against fire

• Ease of implementation

• Corrosion rate

• Durability of the structure

• Elastic properties of the structure

Usually, the builders of residential or office, commercial units, according to the mentioned conditions and the above cases, choose the type of skeleton, i.e. concrete or metal. Naturally, in any case, there is a need to take special measures and take into account certain conditions, such as, for example, in order to use and erect metal structures, it is necessary to use bolts and nuts (such as bridges or stadiums) or welding (in tall buildings). ) is the direction of connections.

In the following, we will examine the details as well as the advantages and disadvantages of each of these two types of structures:

Concrete Structures:

Today, concrete structures (in English: concrete frame) are one of the most popular and widely used types of structures in the world, and many famous buildings and structures in the world have concrete frames. Concrete has many advantages in construction, and for this reason, concrete buildings and structures form a major part of structures in today’s world. As you know, in these structures, unlike metal structures, methods such as welding or bolts are not used in connections.

So far, scientists and researchers have written many books and articles about the importance of concrete and its role in building construction, and have investigated the strengths and weaknesses of concrete frame structures. To build a concrete structure, concrete and rebar should be used, for this purpose, the rebar of the columns and beams of the structure is woven first, and then the mold is prepared by pouring concrete. Due to the need for concreting and concrete hardening, the construction of concrete structures usually takes longer than metal structures.

Advantages of concrete structure:
Concrete structures have several advantages, including:

• Lower cost of construction and maintenance

• Greater resistance to moisture (under suitable operating conditions)

• Having high resistance to fire and heat

• Ability to run in different periods

• More homogeneous materials

• Availability and abundance of materials such as reinforced concrete, cement and rebar

• The need for less knowledge and expertise in design

• No need for welding or installation of bolts and nuts

• More suitable connection of columns and diaphragm to the ceiling

• Having proper stability and durability of bending frames

Disadvantages of concrete structure:
• Need to spend more time for concrete reinforcement and molding

• The need for soil laboratories to test concrete

• Increased weight compared to metal structures

• Reducing the strength and stability of the structure over time

• The need for a false ceiling

• More pressure during an earthquake due to the heavier weight of the structure

• Narrowing the space

• More waste of materials

• Possibility of postponement or longer work in case of weather changes such as rain


Today, metals or alloys such as steel are used for the construction of many buildings, especially skyscrapers. Metals are scattered all over the planet and mankind has long learned how to use them. Especially in road and construction industries. Because the use of metals is very economical and appropriate due to having a suitable melting point, the ability to conduct electric current, the ability to weld, the use of bolts and nuts or riveting, the ability to be flexible and other things.

Of course, in metal structures, important points should be considered, such as the type of connections (welding the structure or installing bolts and nuts) as well as other things such as the possibility of fire or the presence of

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Construction bolt standards

Construction bolts and nuts have special standards, and in fact, it is not possible to install and use any bolt or nut in any project anywhere in the world, but when ordering or buying bolts and nuts in the markets of different countries of the world. You should pay attention to the standard of bolts and nuts. Especially the standards of construction bolts and nuts, which is very important today due to the use of these types of bolts and nuts in various structures.

Types of standards for construction bolts and nuts:
Today, in some specialized construction articles or reports of road and construction engineers, you may come across code numbers or expressions in this field that are incomprehensible or confusing to you. But in order to clarify this issue, we first examine two important standards together:


These two titles are, in fact, two widely used standards that all kinds of construction screws are produced and supplied based on their standards. In fact, today other standards are used in the world of bolts and nuts (including BSI, IEC, ISO, ANSI and AFNOR standards), but the two mentioned standards are accepted not only in the Iranian market but also in many other countries of the world. and most of the bolts and nuts bought and sold for construction purposes are selected from the bolts and nuts produced by these standards. Even in this field, suitable washers are produced and used.

DIN standard:
The word DIN actually stands for “German Institute for Standards” (Deutsches Institut für Normung) and is a German and European standard. The DIN standard was first established in that country in 1917, and since then, the standards of this institution have been the focus of many countries for many reasons, including practicality and principles, as well as the use of them by German industries and many other European countries. is placed

Interestingly, in many cases the ISO standard is very close to the German DIN standard or is adapted from them.
Among the most important and widely used standards of construction screws in the DIN standard, the following two items can be mentioned:

• DIN 6914
• DIN 6916

The official website of this collection:

Standards for construction bolts

ASTM standard:
This bolt standard (abbreviation of American Society for Testing and Materials) is an American standard that applies not only to construction bolts but also to other industrial bolts and more.

The foundation of this standard dates back to 1898 and today the center of this standard is located in Pennsylvania, USA. At that time, a number of scientists, engineers and technicians headed by “Charles Benjamin Dudley” (Charles Benjamin Dudley) started to establish this institution to create a single standard for railway rails and other components. Today, ASTM has branches and offices in other cities and countries such as Washington DC, Canada, China, Belgium and Peru.

This organization has more than 30,000 members and more than 1150 organizations, companies or institutions are also members. Today, more than 140 countries around the world recognize the ASTM bolt and nut standard.

Another important point that you should pay attention to is that, as mentioned, this organization does not set standards for construction or industrial bolts, but many other things are also on the agenda of this organization. For this reason, it is better to familiarize yourself with the codes and abbreviations of ASTM standards – which are not few in number:

A: For materials and metal parts made of iron or steel (such as bolts and nuts)
B: For non-ferrous metal accessories and parts
C: concrete, ceramics and other materials used in construction
D: Miscellaneous materials
E: miscellaneous materials
F: Materials for special purposes
G: Rust, corrosion, destruction, erosion of materials and elements used

The first type, which has the letter A, is related to bolts and other such parts. If we want to set up a list of ASTM standards for bolts and nuts, it would be as follows:

• ASTM A183
• ASTM A193/A193M
• ASTM A194/A194M
• ASTM A307
• ASTM A320/A320M
• ASTM A325
• ASTM A354
• ASTM A394
• ASTM A437/A437M
• ASTM A449
• ASTM A453/A453M
• ASTM A490/A490M
• ASTM A540/A540M
• ASTM A761/A761M
• ASTM A962/A962M
• ASTM A1014/A1014M
• ASTM A1082/A1082M
• B746/B746M-02
• ASTM F432
• ASTM F3125

Of course, among the standards mentioned in this list, only a few of them are related to the standards of bolts and nuts of metal frame structures and buildings, which are:

• ASTM A325/A325M
• ASTM A490/A490M
• ASTM F3125

The mentioned items have many uses in construction today, so that even if you search for structural bolts in English, you will come across one of the terms A325 or A490.

Another important point is that construction screws produced in accordance with the above standards for structures, each one has specifications that actually make up the specifications of that screw, and even the strength and ability of that screw is determined to some extent in this way. to be

The website address of this organization is as follows, from which you can get more information:

Standard construction screws

Comparison of construction screw standards:
Usually, among the screws produced according to A490 and A325 standards, the first type, i.e. A490, has a degree of hardness (or tensile) and greater resistance to heat, cold and pressure, and

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What industries are solar washers used in?

There are various types of washers that are used today in the industry as well as different structures. Basically, the use of washers next to bolts and nuts is essential from the point of view of engineers and experts in science and technology, and it helps to maintain the durability and stability of connections as much as possible.

One of the most widely used types of washers is the solar washer. Solar washers, which are also called star washers, have prominent toothed edges that are like vanes and prevent them from sliding and moving when installed between bolts and nuts. In this way, the connection between the bolts and nuts becomes stronger with the help of the solar washer.

The solar washer greatly contributes to their strength by sinking the tooth-shaped edges into the surface of the connections. For this reason, today in many advanced and industrialized countries of the world, solar washers are among the best and most widely used washers for use in industrial or construction matters. Therefore, buying and selling solar washers in the world is booming.

The application of solar washers, especially barbed solar washers, is usually in petrochemical industries, electrical industries, automobile industries, and also in metal structures.