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What are Bolt Tensioners and How Do They Work?

10/1/2013 11:50:55 AM | by Anonymous

Bolt Tensioners

Bolt tensioners are tools that are used to tighten large diameter bolts properly. Bolt tensioners are easy to use and also save time as they are quite efficient as well. Most methods cause friction loss. One good way to overcome such problems would be to use hydraulic bolt tensioners to overcome the uneven uniformity of tension in bolts. This is achieved by simultaneously using a number of tensioners to ensure that there is an even pull down of the components in the joint. This results in an even tension in all bolts and joints which is consistently leak free. It is important that the bolts be of same tension as if is not, then more stress will be placed on the bolts with tighter tension and over time it will definitely damage that single bolt. Some of the uses of bolt tensioners include heat exchangers, compressor covers, windmills, pipeline flanges, pressure vessels, boiler feed pumps and many others.


How does the hydraulic bolt tensioner work?


There are a number of steps involved regarding on how a hydraulic bolt tensioner works. The bolt tensioner consists mainly of four parts: which are the threaded puller, a load cell, bridge, and a nut driver.


The first step is to place the nut driver over the nut and ensuring that it is at the correct position. Then the load cell and bridge is put on top of the bolt. Next, the puller is screwed on top of the stud that is sticking out on top of the nut face. The hydraulic system will then apply pressure to the load cell, this stretches the bolt. The tommy bar and nut driver are then used to turn down the nut and tighten it. The pressure is then released, which leaves the stud that has been screwed, loaded with the accurate and appropriate amount of tension.


The hydraulic tensioner extends the bolts’ axis point by applying the required hydraulic force in an accurate manner. The first advantage is that the axial extension has no friction between the nuts and bolt threads. This greatly reduces wear and tear of the bolts, extending their life span. There is also no friction between the assembly surface and the bottom surface of the nut. The second advantage is that there is no torsion force, also known as ‘parasite’ force; this means that the tension force applied to the bolt will not damage the bolt in any way. Another plus point is that the traction load can be tracked and controlled. This means that the status of the bolts can be determined and the correct force can be applied if needed depending on the current status of the bolt. As mentioned earlier, bolts can be tightened simultaneously, this means that not only will it be more consistent but also it will save time. The company can also contact the manufacturer if they wish for a custom bolt diameter; the standard diameter ranges from 20mm to 50mm. Since the hydraulic bolt tensioner uses hydraulic forces, the need for physical effort is greatly reduced.

Uses of bolts


Bolts are usually used to hold pieces of equipment together in the long or short run. Most of the structures which contain steel are held together by bolts. For example, one of the most famous landmarks in the world, the Eiffel tower was bolted together. Since then, the structure has lasted over a hundred years. The empire state building in New York, USA was also bolted together when it was built. Further applications can extend to one’s household such as keeping the pieces of furniture together.


Most bolts can be found on metal machinery such as planes, ships, cars and many more. As they are used to lock pieces of equipment together, they are quite important inventions in order for many of our equipment to be in a safe and working condition. For applications that come into contact with water such as ships, the bolts have to be coated in a special material to prevent rusting. If the bolts fail to serve their purpose, then the ship may be seen as unsafe.
Thus, thanks to bolts, we now have many grand structures. Like many other items, people still do not know that such a small piece of invention could be so useful in many types of equipment. Not only that but we can use our equipment in peace knowing that they are being held together.

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