Accidents caused by the loosening of bolt and nut connections (part one)

Articles, Educational

One of the main components in structures, whether steel or iron, are connections, whose quality plays an important role in the transmission of pressure and forces. Nowadays, if ordinary people are asked about the role of bolts and nuts, most of them do not consider it very important, while if quality connections are not used, the safety of the whole structure is jeopardized. In the finished structures, the connections are not visible, but in fact, it is these connections that guarantee the quality and security of the structures.

The role of bolts and nuts in huge structures is very important, therefore, the owners of various industries, using the opinions of their consultants, should always be double sensitive in choosing connections to avoid any accidents.

One of the reasons for the occurrence of these irreparable accidents is loosening of connections due to vibration or a gap created between bolts and nuts. This phenomenon can have many risks, including the risk of life. To prevent this accident, the following information can be useful for dear users. be One of the solutions to prevent this is:

1- The use of various types of spring washers, which are very different in terms of standards and shapes, and the names of these washers in English are as follows:


and other types of washers.

According to the suitability of the structures, different types of washers are used for a specific purpose. As you can see, the role of washers in metal structures can never be ignored. Washer production is considered as one of the important jobs in advanced or developing countries, including our dear country Iran, where many people are active in this field. It should be noted that many washers are not produced in Iran and are imported because for this purpose sufficient facilities and technical knowledge are required.

2- Using locking nuts. In addition to washers, we can also mention nut and half nut locks, which are special for flexible structures, including bridges and high structures, and builders and designers should use experienced consultants to choose the right connections for these structures.

You might be wondering what a half nut is: Nuts whose height is half a regular nut and are according to DIN 439 and DIN 936 standards.

The role of these nuts when tightening the nut is that the main nut is assembled and the crack meter is made, then the half nut is closed on it and tightened very little with a hand wrench, and this prevents the main nut from opening or loosening.

The most sensitive part is the use of bolt and nut connections in lifting and cranes, which should be very careful to choose connections, and after installation, periodic visits should be continuous and accurate, because if the aforementioned items are not followed, unfortunately, accidents will occur. We will be heartbroken in terms of life and money.

3- Lock tite use of lock tite.

Locktite is a type of liquid glue that can be used to connect two solid surfaces. LockTite is a locking and tightening adhesive for threaded connections, which is divided into three groups: low strength, medium strength, and high strength, which are selected based on their application. These adhesives are used to lock the holding parts in place and prevent them from loosening due to vibration and even temperature changes. How to find out that the closed bolts are loose?

1- The periodic visits made by the project engineers and guarantee the bolts and nuts for certain periods of time. These visits are done by technicians with different methods and tools.

2- Re-tightening which, for example, in some projects, visits are done regularly and monthly or annually. All the mentioned items are necessary to ensure the performance of any structure or equipment. Unfortunately, it has been heard a lot in the news that some refineries have exploded or some bridges or huge structures have collapsed. It can be said with certainty that more than 50% of these incidents are due to inaccuracy in using the mentioned items.

Hoping for the day when using quality connections and observing safety precautions, we will not witness any more tragic incidents for our countrymen.

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