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The Experts: Superbolt – your flexible friend

Flexibility of Superbolt tensioners improve bolted joints

First published in Bolted #1 2014.

Q: How does the added flexibility of Superbolt improve the bolted joint?

A: In normal bolted joints, the stress concentration of loads on the first 1-2 threads is one of the main reasons why a bolted joint fails. With a joint utilizing Superbolt multi-jackbolt tensioners, as the jackbolts are torqued to stretch the stud/bolt, the tensioner body radially flexes in at the top and flexes out at the bottom. This flexing action transfers the load from the first few threads and distributes the load evenly throughout the entire engaged thread length between the tensioner and stud/bolt. This simple flexing action dramatically increases the strength of the joint by reducing the stress concentrations on the first couple of threads.

In addition, this radial flexing action combined with axial flexing results in added elasticity in the joint. In a typical bolted joint, the average clamp length of the joint is around 2 to 5 thread diameters in length. The combined flexing in the MJT creates a higher load point, which increases the clamp length of the joint by as much as 2-3 thread diameters. It can be concluded that the Superbolt tensioner could double the elasticity of a standard bolted joint. This eliminates the need for lengthening the bolt/stud and adding a spacer or multiple spring washers, (both of which can be costly), to improve the elasticity of the joint.


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Have you seen the Superbolt product video yet? Check it out now!

Video: Nord-Lock Group shares bolting solutions to the Power Generation industry

Nord-Lock Group interview segment at Power-Gen International

Jennifer Van Burkleo, host of Power-Generation week connects with CEO of the Nord-Lock Group, Ola Ringdahl to look at how the Nord-Lock Group is a trusted partner in bolting solutions.

Ola was happy to discuss with Jennifer each of the product line by the Nord-Lock Group and how it can secure the power industry. “We are very excited to educate the power generation industry on our three product lines we have to offer; the Nord-Lock wedge-locking washers, Superbolt tensioners and Expansion bolts, and now our latest addition from earlier this year, Boltight hydraulic tensioning system,” says Ola Ringdahl, CEO of the Nord-Lock Group

Power generation is an important industry, we secure bolting applications that need to withstand enormous pressure in extreme conditions. Solutions from the Nord-Lock Group can be found in countless applications including wind turbines, solar panels, steam powered generators, hydroelectric valves and many others.

Watch the full video below or visit the Nord-Lock Group YouTube Channel.

Video: Tips on reusing Nord-Lock washers

Tips on reusing Nord-Lock washers

Nord-Lock washer is reusable, but the reusability depends on the conditions of usage. Basic steps should be conducted to verify full functionality and to ensure correct reassembly of the washers. Watch the video below to find out more.

Have you seen the new Junker vibration test video yet? Check it out now!

More videos available on the Nord-Lock Group YouTube channel.

The Experts: What effect will Nord-Lock washers have on my surfaces?

Effects of Nord-Lock washers on the surface of your application

First published in Bolted #1 2011.

Q: Will Nord-Lock wedge-locking system damage the surface in my application?

A: Nord-Lock washers are specially designed to create impression marks without scoring the mating surface. The impression marks are important since they prove that the serrations grip correctly into the mating surface. In bolted assemblies rotation always takes place where the friction is lowest. Provided that sufficient impression marks are created any tendency to rotate will occur between the cams of the washers. Consequently, any rotation is prevented by the wedge effect of the cams.

When a joint secured by Nord-Lock washers is tightened, rotation always takes place between the upper washer and the bolt head or the nut. The serrations are simply pressed down into the material, no scoring of the mating surface occurs. The bolt head/nut is hard enough to withstand the minor scoring that it is exposed to. During untightening rotation takes place between the cams of the Nord-Lock washers. Therefore there is no risk of damaging the surface in the application. The impression marks slightly increase the compressive stresses in the surface, but they will not score the material or damage it.


Do you have a question about bolt securing?
Put the Nord-Lock experts to the test.
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Video: Verifying the locking function of Nord-Lock washers


Nord-Lock washers are delivered pre-assembled in pairs to ensure correct mounting and ease of installation. The locking function of the Nord-Lock washers can be verified using some simple steps, watch the video below to find out more.

Have you seen the new Junker vibration test video yet? Check it out now!

More videos available on the Nord-Lock Group YouTube channel.

Superbolt tensioners secure slurry pump cover

Superbolt multi-jackbolt tensioners secure pump cover


Two sets of hydraulic wrenches were used previously, with one used to achieve 21,000 lb•ft (28,470 Nm) on the 16 perimeter bolts and another used to achieve the 35,000 lb•ft (47,450 Nm) for the cut water bolt. The larger hydraulic wrench could not be used for all of the nuts because it would not fit.

Four millwrights were needed for the installation. The hydraulic tools weighed 51.5 lbs (70 N) and 96.5 lbs (130 N), with the smaller tool needing to be passed from worker to worker. The customer had trouble correctly placing the reaction arm, and safety was a concern.

Additionally, scaffolding was put into place in order to perform the task, requiring additional time and effort. Total time to complete the torque sequence was 2.5 hours.


Superbolt multi-jackbolt tensioners (MJTs) were purchased and directly compared to the previous hydraulic wrenches method. For the initial passes, electric impact wrenches were used. This speeds up installation. To obtain the final target torque value of 80 lb•ft (108 Nm), two 1/2” torque wrenches were used.

Because only hand tools were needed, the safety and weight concerns associated with the hydraulic wrenches were eliminated, and only two millwrights were needed instead of four when using the previous method. Also, no scaffolding was needed for the installation. In the end, the customer experienced a substantial time savings. The total time to complete the torque sequence using MJTs was only 1 hour!

The millwrights involved in both installations were experienced with the hydraulic tools, but this was their first experience with Superbolt tensioners. The satisfied customers had nothing but positive things to say about the MJTs, with one noting: “Definitely the way to go.”

The Nord-Lock Group Introduces Boltight at 2015 Power-Gen International

Power-Gen-Collage-675px X 310px-

Power-Gen International is the largest power generation event that focuses on the latest product trends and innovations within the industry. This year, the event was held in Las Vegas, Nevada (USA), from 8th to 10th of December. The participation of the Nord-Lock Group was an important event as it was the first public showcase of Boltight hydraulic tensioning since the company’s acquisition in September this year.

The extensive range of bolting solutions from the Nord-Lock Group was displayed during the three days event, which attracted crowds of visitors to the booth. Visitors were able to interact with Nord-Lock engineers and catch the live demonstration of the bolting solutions, which include Nord-Lock wedge-locking washers, Superbolt Multi-Jackbolt Tensioners and Boltight hydraulic tensioners. Nord-Lock bolting experts also presented the application references and benefits of each product line within the power generation industry. Boltight was a highlight, generating huge interest from many visitors as these innovative products are commonly used in applications on steam, gas, wind, hydro and tidal power generation plants.

“Power-Gen International is one of the most important shows for the Nord-Lock Group. We are very pleased to present the Boltight hydraulic tensioning system. Boltight is a great addition to the Nord-Lock Group portfolio, putting us in the right direction of being the leader in bolting solutions,” said Ola Ringdahl, CEO of the Nord-Lock Group.

Agility Group improves safety miles from the nearest coast

Agility Group secures with Nord-Lock wedge lock washers

The failure of a bolted joint in the offshore Oil & Gas industry not only could lead to catastrophic consequences for personnel and the environment, but also for the bottom line.

On crucial bolted joints Agility Group, a Norwegian engineering, procurement and construction company, uses Nord-Lock safety washers – to the delight of its drilling company customers. From the Gulf of Mexico to the far north of Norway, Agility Group’s PetroFlame® burner booms are trusted by drilling companies to safely flare off oil and gas when the pressure in the well reaches dangerous levels. Jutting out some 30 metres from the side of oilrigs and drill ships, these burner booms are battered by wind, sea spray, and subjected to heavy vibrations, fierce sunshine and ice build-up.

Since being introduced to Nord-Lock Group and their wedge lock products about five years ago, Agility Group has become a loyal customer. And it is not just its own engineers and designers who have come to appreciate performance and reliability of the Nord-Lock wedge-locking technology. “Our clients often ask us how we have secured the bolts. When we say that we use Nord-Lock wedge lock washers, they are confident that everything is okay. They know what Nord-Lock wedge-locking system is and what it does.” says Tom Mathisen, Agility Group’s Project Manager Marine Solutions.

Each burner boom – the Swan-Neck, Cantilever and King Post Mounted PetroFlame® – has several hundred bolted joints and for many of the most crucial ones, such as the pipe supports, access platforms and walkways, Nord-Lock wedge-locking system is used.

“With Nord-Lock washers we can reduce that to one nut, which makes installation easier and we consider it to be a more secure solution.” says Structural and mechanical design engineer Stian Jenssen.