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Superbolt multi-jackbolt tensioners (MJTs) offer an innovative technology for tightening bolts & studs. Superbolt products have been proven and established as a preferred solution for bolting in every major industry, all over the world.

Our multi-jackbolt tensioners offer you simple and cost effective tightening, even for large size bolts. Your joints can be tightened with high accuracy without requiring specialist skills or heavy tooling. MJTs ensure a profitable life cycle cost by improving the bolt design for OEM manufacturers, ensuring reliable operation and by facilitating maintenance procedures. 


Complete solutions

From space to deep sea, from small to large - no matter what your bolting challenge is, we have done it before. Bring your bolting questions to us and we will work with you to find the best possible solution.


The innovative bolting solution


What is Superbolt?
Superbolt tensioners are designed as direct replacements for conventional nuts and bolts. These devices can be threaded onto a new or existing bolt, stud, threaded rod or shaft. The main thread serves to position the tensioner on the bolt or stud against the hardened washer and the load bearing surface. Once it is positioned, actual tensioning of the bolt or stud is accomplished with simple hand tools by torquing the jackbolts which encircle the main thread. The jackbolts transfer the preload evenly into the main thread and, consequently, onto the joint. The main thread is tightened in pure tension.



How Superbolt tensioners work:


1) By tightening the jackbolts, a strong thrust (axial) force is generated. This thrust force is directed against a hardened washer. Jackbolts have a small friction diameter and can therefore create a high
thrust force with relatively little torque input.

2) The loads are transferred through the nut body which is positioned on the main thread by hand.

3) A hardened washer is used to transfer the force while protecting the flange face.

4) The thrust (axial) force of many jackbolts and the opposite reaction force of the main bolt head create a strong clamping force on the flange.

5) The thrust (axial) force from the jackbolt creates an equally strong reaction force in the main bolt.


The advantage is obvious, but how exactly do our multi-jackbolt tensioners achieve this? As you can see in the animation below, the hardened washer is installed first. Then the nut body is threaded onto the existing stud or bolt, hand tight against the washer. The jackbolts are then tightened and thrust against the hardened washer. Accurate preload is achieved on the stud by torquing the jackbolts.

Our bolting technologies come in a variety of custom configurations, meeting the requirements of virtually every type of application. MJTs are available in both nut and bolt style, and we also can supply studs, expansion bolts, flexnuts, thrust collars and more. Visit our products page for more information.