BOLTED

A forum about optimizing
bolt securing

HyFit™ and EzFit™ expansion sleeve coupling bolts

Bolted coupling challenges resolved!

Superbolt range of expansion sleeve coupling bolts offers a wide range of flexibility in application – suitable for through hole couplings, blind hole couplings – even applications requiring accurate location of components without axial load. The expansion bolts can be retrofitted to replace traditional interference and other types of coupling bolts most reliably and cost effectively.

Maximize availability

  • No coupling slippage or stuck bolts
  • No hole damage or re-machining
  • Fast and easy to install and remove
  • Concentricity established and held

 

Benefits

  • Maximize plant availability
  • Effective planning
  • Time saving solution
  • Improved overall coupling performance
  • Improved site safety
  • Reliability

 

The mechanical expansion bolt, now known as EzFit, is a long-established product with design capability for all types of couplings requiring truly fitted bolts, commonly used for Hydro turbines, Marine propulsion drive coupling, large motors and gear rings that require component location accuracy.

HyFit hydraulic expansion bolt is a newly advanced product that can replace all designs of coupling bolts. Main applications are found in power generation including conventional steam, high efficiency gas, hydro and wind turbines. With HyFit installed, customers benefit from both operation improvements in coupling performance along with saving time during plant maintenance periods. The innovative design features significantly reduce the risk of causing damage to the bolt or bolt hole, and address safety issues commonly experienced with alternative coupling bolt solutions.

The extensive product range of HyFit and EzFit expansion bolts provides the best options to fit your application. Furthermore, the unique features and advantages of both hydraulic and mechanical expansion sleeve coupling bolts can be combined to suit specific requirements.

 

More: HyFit hydraulic expansion sleeve coupling bolts

More: EzFit mechanical expansion sleeve coupling bolts

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Focus on security in windy and vibrating environment

23 August 2017
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Text: Alastair Macduff

photo: Akkadia, 06photo

First published in Bolted #1 2017.

THE CHALLENGE
Dutch company Akkadia manufactures specialist CCTV systems for demanding situations in various industries. Its cameras can be found everywhere, from offshore, to polar regions and deserts.

Since 2010, Akkadia has had a contract with the Dutch Ministry of Infrastructure and the Environment (IenM), providing CCTV technology in tunnels throughout the Netherlands. Tunnel cameras must be particularly durable, as the vehicles that constantly pass close by create huge wind pressure. Standard security cameras normally don’t last more than a year and a half.

THE SOLUTION
Akkadia developed a specific camera for tunnels – the PTZ – as a stainless steel, vibration-resistant application, built to last more than ten years. To create and maintain such robust technology requires a high-quality locking solution.

The IenM were keen to use its usual self-locking nuts, but Akkadia were already employing a product that would ensure the ability of its cameras to provide long-term, trouble-free traffic surveillance.

Akkadia had entered into partnership with Nord-Lock and fit its washers in the CCTV camera technology. The IenM was subsequently won over by convincing evidence presented by Akkadia about the quality of the Nord-Lock washers, including test reports from TÜV in Germany. The PTZ tunnel camera utilises NL6 and NL8 steel and stainless steel washers on the inside, and NL10 stainless steel washers on the mounting and base.

THE RESULT

All moving parts and internal connections on Akkadia CCTV systems are secured by Nord-Lock washers; from the housings to the base plates.

No problems have been reported in the six years that Akkadia has supplied tunnel cameras to the IenM. Akkadia has now manufactured around 800 systems featuring the Nord-Lock solution. Currently, over 400 PTZ tunnel cameras cover two large motorway projects in the Netherlands – the Amsterdam Orbital, and the Maastricht motorway near the Belgian border.

The success of Akkadia’s tunnel cameras highlights the importance of total cost of ownership. In thinking long term, the IenM has saved money on the cost of maintenance and replacing broken cameras.

The Experts: Preventing galling and seizing

10 August 2017
2 comments

Text: Lena Kalmykova

photo: Jason Milburn

First published in Bolted #2 2013.

Q: When and why does galling and seizing appear?
A: Galling is caused by a combination of friction and adhesion between metallic surfaces during sliding. When galling occurs material is adhesively pulled from one surface leaving it stuck on the other in the form of a lump. This process spreads rapidly as the built up lumps induce more galling.

The tendency of material to gall is affected by the material’s ductility. Typically, softer materials are more prone to galling while harder materials are more resistant.

In bolting, thread galling appears during fastener tightening as pressure builds up between the contacting and sliding thread surfaces. Thread galling commonly occurs with fasteners made of stainless steel, aluminium, titanium, and other alloys.

In extreme cases galling leads to seizing – the actual freezing together of the threads and bolt lock-up. Continued tightening may lead to the breakage of the fastener or result in torn off threads.

Solution:

  1. Lubrication of the internal and/or external threads.
  2. Reduction of the installation RPM speed.
  3. Selecting different stainless alloy grades for the bolt and the nut reduces galling resulting from different degrees of hardness. However, the strength of the nut always needs to be greater than the strength of the bolt.

 

ASK THE EXPERTS
Do you have a question about bolt securing?
Put the Nord-Lock experts to the test.
Email your questions about bolt securing to
experts@nord-lock.com

Tips and tricks: How to optimise a bolted joint through clamped length

First published in Bolted #1 2017.

Q: What is clamped length?
A: Clamped length – LK – is the free length of a bolt that is stretched under tension, meaning:

  • In a through hole (A), the distance between the bolt head and the nut.
  • In a blind hole (B) – or for a stud bolt (C) – the distance between the head (nut) and the first thread engaged in the tapped hole.

 

It is also called “grip length” as the total thickness of clamped parts under compression.

To optimise a bolted joint, it is recommended to design the clamped length to at least 3 or 5 times the bolt diameter. Increasing the elasticity of the fastener greatly improves the properties of the joint, as it:

  • Increases the elongation of the bolt, reducing settlement effect.
  • Increases the flexibility of the fastener, reducing the risk of self-loosening under vibrations and transverse loads.
  • Improves the load factor, reducing the amplitude of dynamic stresses in the bolt and minimising the risk of fatigue failure.
  • Minimises the load transfer loss in case of hydraulic tensioning.

 

For stiff joints that don’t permit a long clamped length, it is possible to implement smart and effective solutions to avoid failure. Instead of using expensive and unattractive spacers, you can, for example, use:

 

ASK THE EXPERTS
Do you have a question about bolt securing?
Put the Nord-Lock experts to the test.
Email your questions about bolt securing to
experts@nord-lock.com

 

Video: Nord-Lock washers Junker vibration test

Video: Superbolt multi-jackbolt tensioners

Download: Nord-Lock washers CAD files

Nord-Lock Group keeps the railway industry on track

First published in Bolted #1 2017.

Starting with ROLLING STOCK some 20 years ago, Nord-Lock wedge-locking washers are now found in all safety-related areas of the railway industry, such as bogies, coupling devices, brake systems, rail dampers, housing, and many more.

Nord-Lock washers ensure the functionality of bolted joints, even at the highest levels of vibration caused by rail traffic. One example is in railway switches, highly complex structures that must be used as long as possible with minimal maintenance, while exposed to the elements and to considerable stress.

Nord-Lock steel construction washers (NLSC) help railway companies avoid operational downtime, thus saving money. When renovating or replacing old bridges, small temporary bridges are assembled on site with a bolt preload of 100 percent to achieve secure bolted joints. However, these bolt connections can only be used once. Using Nord-Lock washers, the preload can be reduced.

Overhead line masts and signal masts must cope with severe dynamic loads caused by passing trains. Given the large number of masts, reliable bolt connections are crucial to reducing maintenance costs. With their special geometry, Nord-Lock X-series washers increase security, including on bolted joints with short clamp length, as well as in softer materials.

A recent application for the Nord-Lock X-series is noise-absorbing walls, which cope with extreme vibrations from passing trains. In Germany alone, 3,000 km of noise-absorbing walls are to be installed by 2030. A combination of concrete bolts and X-series washers is used to attach noise-absorbing barriers on existing bridge decks, many of which were not designed for noise barriers.

 

Video: Nord-Lock washers Junker vibration test

Video: Multifunctional Nord-Lock X-series washers

More: Nord-Lock Group solutions in the Railway industry

How the Expander System Group came to life and evolved

12 July 2017
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Text: Ulf Wiman

photo: Stefan Jerrevång

The Expander System Group, the latest Nord-Lock Group acquisition, shares many customers with its new parent company and their history is remarkably similar. Founded in a remote part of Sweden, evolving from an innovative idea. In Expander’s case, a rusty nail was transformed into market-leading pivot technology. Founder and former owner Roger Svensson tells the story.

First published in Bolted #1 2017.

What is Expander’s business?
“Our patented Expander System is a state-of-the-art, cost-effective solution that permanently ends pivot wear in construction, forestry, mining and other heavy machinery. Fitted in the pivot, a double-locking expanding pivot pin assembly increases stability and safety and eliminates welding and line boring of worn-out pivot lug ears. The system has been field-tested for over 50,000 hours without failure.”

How did the company start?

“My father, Everth, and his twin brother Gerhard, did road work in the 1950s, starting out with one bulldozer. Machinery joints and pivots are prone to wear and tear, leading to expensive downtime and repairs, but they came up with a makeshift solution, knocking a rusty nail into the lughole to eliminate the gap. This worked surprisingly well, which inspired them to start developing the technology.”

When did you get involved?
“I learned about their ideas and immediately saw the potential. My father and I founded the company in 1986. At quite an early stage we got involved with computer engineers in the development of a parameter-controlled CAD system. This is an invaluable tool, as each Expander System is custom made to fit customer-specific applications.

In the 1990s we expanded geographically. North America is a huge market and in 1997 I moved there to get a business foothold. The launch was successful and in 2006 we established our own production facility in North America.”

Why did you sell the company?
“Enormous markets, such as South America, are starting to develop, but you need local presence. It was about either setting up my own network or selling to someone that already had a global subsidiary and distributor network. We already collaborated with Nord-Lock and after several discussions with Ola Ringdahl, CEO, Nord-Lock Group, I was sure that the Nord-Lock Group was a perfect fit.”

What does Expander bring to the Nord-Lock Group?

“There has been a major change in how people view repair and maintenance, which makes the market potential for the Expander System huge. We’ve only scratched the surface.

Also, we and the Nord-Lock Group have often shared customers, but solved different problems. Bringing our solutions together – and cross-fertilising them – will make our portfolio and product range so much stronger, which will benefit the customers.”

Facts: Roger Svensson
Role: Founder and former CEO, Expander System Group.
Age: 56.
Lives: Sedona, Arizona, USA.
Background: Studied Economics/Political Science at UCLA (double major). Member of the UCLA team that won the prestigious NCAA swimming championships in 1982. Held a couple of positions with other companies before starting Expander with his father in 1986. “I have always been an entrepreneur.”
Passion: Music: sings, plays guitar and writes his own songs. Is currently working on his debut album. Also paints and likes to write.

Washers keep airplanes in the air

First published in Bolted #1 2017.

Look up into the sky in the coastal city of Miri, in north-eastern Sarawak, Malaysia, and you may see Nord-Lock washers in action: inside a radio-controlled aircraft. These hobby airplanes are sold by Byond Horizon, a business that otherwise uses drones to take aerial photos and videos for companies.

“Unlike our drones, these recreational aircraft use gasoline-powered engines,” says Mr. M. Fadzly of Byond Horizon. “These engines cause a vibration problem. Since the frame is made of wood, which is soft, and the engine and its mounting are made of steel, the bolts holding them together can come loose after only four or five flights.”

Fadzly says that it can be difficult to access the plane’s engine, so the loosening is a real problem. A friend of Fadzly’s, however, works at Mayura Engineering and is a supplier of Nord-Lock washers.

“I ordered a box, tried them out, and now I recommend them to all of my customers when we are assembling their airplanes,” says Fadzly. “The Nord-Lock washers never need to be retightened, and they also make sure the engine stays in place. It would be quite dangerous if the engine were to fall out during flight.”

Fadzly not only sells the radio-controlled airplanes, he flies them himself. “I’ve been doing it since 1997,” he says. “It’s a passion, and a fun thing to do on the weekend. It gives you the feeling of flying a real airplane.”

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Boltight subsea hydraulic bolt tensioners

Boltight manufactures both standard and custom built tooling for subsea applications. The subsea tensioners incorporate components that helps to save installation time, cost efficient, protects the environment and conforms to the requirements of the European Pressure Equipment Directive.

All subsea tensioners are assembled, filled with oil and have been pressure tested before dispatch. Boltight subsea tensioning tool is supported by a range of ancillary equipment such as high volume pumps, diver control valves, long length down line and hose reels.

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