First published in Bolted #1 2017.
Market share, North America: 60% for mulching machines
Location: Factory in Quebec, Canada. HQ in South Carolina, USA
Products used: NL3/8″ & NL 20 washers
Applications: Mulching machines, bio-energy balers
The importance of sustainability in land clearing is reflected in the product range of North American company Gyro-Trac. With a 21-year history of manufacturing mulching machines, its focus is now also on creating bio-energy balers for easy packaging, transportation and storage.
As the mulching machines clear unwanted trees, this green technology leaves soil structures intact, eliminates erosion and run-off pollution. The machines can mulch trees to the ground, leaving the roots of neighbouring trees undamaged.
Nord-Lock has provided high-quality wedge-locking washers to Gyro-Trac for around 15 years. The washers maintain the balance of their mulching machines, extending the life cycle and sharpness of the teeth in the process.
The washers also play an important role in Gyro-Trac’s Bio-Baling System. The system involves compressing biomass in such a way that no compost is created and no burning is required. For Gyro-Trac’s customers, the added costs of hauling and dumping are eliminated, while onsite storage of the one-tonne bales promotes sustainable land use.
Daniel Gaudreault, owner of Gyro-Trac, says: “The teeth are the heart of the machines we produce. We have never had a problem with Nord-Lock washers and their reliability has been vital to our continued success.”
First published in Bolted #1 2017.
Don’t miss the new Nord-Lock Group video that focuses on the hands-on aspects of our Expansion bolt technology.
The video takes you through an entire Superbolt Expansion bolt installation process, from preparation and positioning to the fitting of the bolts into the holes when aligned.
The video was filmed on location at the EDF hydro electric power station, Usine Électrique de Malgovert, in the beautiful French Alps, where electricity generator giant EDF joined forces with the Nord-Lock Group to install Superbolt on the Malgovert turbines.
“EDF chose Superbolt Expansion bolts to simplify future maintenance. Ease of installation and removal due to the expanding sleeve technology insures against future damage to coupling bolt and coupling holes. There is no longer a need to re-machine holes or replace bolts,” says Steve Brown, expansion bolt specialist with the Nord-Lock Group. “This film is for everyone who wants the optimal bolted coupling, using and making the most of a Superbolt installation.”
The March issue of Bolted magazine will be hitting the desks soon! As usual we invite you on a journey to explore interesting cases and insights from the world of bolting.
This edition’s theme article revolves around hydraulic torquing and tensioning. We play off one against the other in an attempt to answer which is the best method of tightening critical bolts.
In the process of creating this issue we have talked to many satisfied customers from around the world! We will take you to Nuremberg where we have a closer look at a better and more cost-efficient way to renovate track beds in their railway underground system, without weeks of construction and chaos caused by delays and diversions.
This issue also features sustainable mulching machines exposed to extreme vibration, KTM sports motorcycles solving issues with customized Nord-Lock products, and a customer who creates waves with a special buoy as a source of renewable energy.
At the same time we are glad to inform that this edition is also available in Spanish! Bolted magazine is now published in 9 languages: English, German, French, Swedish, Finnish, Japanese, Chinese, Korean and Spanish.
Want to receive your complimentary copy of the Bolted magazine? Click below and subscribe now!
Stora Enso focuses on providing renewable solutions in packaging, biomaterials, wooden constructions and paper globally. The company has realized the benefits of the Expander System’s unique solution and mounted Expander pivot pins on their packaging machines where the pivot wear was extensive.
The result was prolonged life span of the machines and no downtime due to pivot wear.
‘We use the Expander System because it is easy to install.’ – says Lennart Larsson from the Hydraulics department at Stora Enso.
The pivot pins are installed directly into the existing mounting without expensive and time-consuming welding and line-boring. ‘These pivot pins mean less wear and definitely made our lives easier’.
Boltight’s Xtra Load range of bolt tensioners is used extensively in the offshore oil and gas industry for bolting compact flanges.
The 1500 bar system delivers 30% more load than Boltight’s standard range in a smaller space envelope without compromising on safety, reliability and accuracy. This lightweight and innovative design was developed to suit all common sized ANSI, API and Norsok L005 compact flanges.
Watch the video demonstrating the tensioning process with Xtra Load tensioner.
Click here for more information about Boltight.
Gamleby Forest is a logging company with a number of harvesters in their fleet. The machines generally operate year round and eliminating expensive downtime is always a priority at Gamleby.
Upon inspection of one of the harvesters, the machine operator discovered a wear in the lugs between the boom and pillars. The owner of the company, who often does repairs himself, had some experience with the Expander System in the past. He immediately decided to replace the original pin in the harvester with the Expander solution.
The whole replacement process took merely two hours. The Expander solution was installed directly into the worn lugs. The double-sided locking on the Expander pivot pin provided increased stability, security and minimized wear in the joint.
If Gamleby Forest chose to use a new original pin instead of pivot pin from Expander, they would have to transport the harvester to their workshop to mount the pin there. Practically a whole day would be required to complete the replacement. A traditional repair, moreover, would only solve the problem for the moment – wear would occur again.
After the replacement the harvester was back in the operation within a couple of hours and Gamleby Forest became yet another satisfied customer of the Expander System.
The Yanacocha Mine in Northern Peru is one of the largest gold mines in the world. As in any industry, downtime means lost productivity and – as a result – lost money. Keeping the operations running is always of the utmost importance.
Minimizing production shortfalls and lowering the life cycle cost of the machinery and equipment is a constant challenge for the service and maintenance crew.
The useful life of the conventional pins in the stabilizer linkage on CAT’s 793B fleet was calculated to be 5.000 hrs. The machine was then brought in for disassembly, line-boring and re-pinning as part of crew’s maintenance schedule.
In 2003 the decision was made to put Expander System to the test.
A mining truck was fitted with pivot pins from Expander System and they outlasted the conventional solution by four times. The Expander pivot pins were checked every 5.000 hours and were not replaced until the 20.000 hour maintenance check. During the replacement no line-boring was needed and the whole procedure was completed in a few hours instead of days as it would in case of the conventional solution.
The cost savings where Expander pins were fitted were calculated to be over $30.000. While the test was ongoing and proven successful, the Yanacocha Mine maintenance department decided to start using the Expander System in many other pivot applications on their haul truck fleet.
The Yanacocha Mine is also using the Expander System on several vital wear points on Motor Graders and Wheel Loaders.
First published in Bolted #1 2017.
Nearly everyone has tightened a nut at some point in their lives and can understand the basic concept of torquing. It is the oldest, simplest, and for most non-engineers, the only method of tightening bolted joints.
Whether by hand or hydraulics, compared to other methods, simple to understand basics of torquing make it overall a far more cost-effective option. This does not dismiss the need for training and understanding of the key factors in torque tightening.
“With one torque wrench and a range of sockets, you can tighten quite a wide range of nuts and bolt sizes,” says Robert Noble, Technical Director, Asset 55. “It offers quite a bit of flexibility, and it’s easy to explain to a technician how to use torque equipment.”
Given that it will be effective in the majority of applications, it is clear why it is often the default first choice.
Hydraulic torquing has its limitations, particularly friction, which Noble labels, “the number one enemy of torque.” Typically, friction accounts for 90 percent of the torque applied to the nut, which means only a small portion of torque will translate into useful bolt load. Because torquing is an indirect way of loading, it is difficult to predict the exact bolt load. Many factors should be taken into consideration, in particular the lubricant used, the need to avoid possible contamination and a good surface finish on the nut bearing surfaces. This must be overcome to ensure reasonable accuracy when using torque to produce preload and can be a significant disadvantage in critical joints.
Noble stresses that with good procedures, calibrated equipment and competent personnel, torque tightening can be used successfully on most joints. Much is made of bolt scatter, which will see the achieved preload on an individual bolt within +/– 25 percent of target, but on a flange with multiple bolts the usual result is to achieve an average bolt load within close range of target (providing good practice is followed and the coefficient of friction is assessed). “This is accurate enough for the majority of gasketed flange joints, so torque remains a very viable technique,” Noble says.
Hydraulic tensioning of bolts began in the 1970s, pioneered in part by British engineer Fred Heaton, who would go on to found companies Hydratight and Boltight. Over the next 20 years it gradually became more common and is now becoming the preferred method for tightening large critical joints in many industries, such as oil and gas, wind, subsea, or power generation.
Compared to hydraulic torquing, it is a more complex procedure that involves more specialised equipment. In certain applications tensioning can offer greater accuracy and control, as well as speed of assembly. It is particularly advantageous on flanges with multiple bolts. Using conventional torque, each bolt is tightened one-by-one in a pattern, which must be applied carefully to avoid the risk of putting too much load on one side of the gasket or flange. By attaching multiple tensioners, it is possible to tighten a number of bolts simultaneously for an even compression of the gasket.
“This is essentially where hydraulic tensioning came from,” says Nitin Patel, Projects and Commercial Manager, Boltight. “It allowed people to control the clamping force and if you could do it all in one go, around the whole circumference, that would be much better for the gasket, much better for the joint, and you could actually predict the load that is in that joint.”
Another perceived advantage of tensioning is improved accuracy, but as Noble points out, it’s not always that simple. “Unfortunately, the industry tries to use simple one-size-fits-all rules but they do not apply to the torque and tension criteria,” he explains. “Where the conditions are right, tensioning can become very accurate. Typically, that would be for bolts with a high length-to-diameter ratio – long, thin bolts – and where you have high bolt loads. In these applications tensioning is more accurate than torque. But conversely with short, fat bolts and low bolt loads, tensioning becomes less accurate.”
Tensioning also has its disadvantages, namely load loss, which occurs when the tensioner is released and the load transfers to the nut. To compensate for this, the load loss is estimated and the technician applies the expected load loss in advance. This means that the bolt, gasket and flanges are subjected to greater stress than the targeted assembly stress. This has to be taken into consideration either at the joint design stage or prior to using the tooling. An alternative is to repeat the tensioning procedure to compensate for the settlements.
Hydraulic bolt tensioning can also have practical and logistical drawbacks. Since it requires more equipment and specialised tools, it can be significantly more expensive. “Tensioning is not easily understood, other than by those who tension regularly,” says Noble. “You need specific tension tools and it’s difficult to design a tensioner range with the same flexibility as a torque wrench.”
So the truth is that there is no simple answer to which one is better, torquing or tensioning. It is best decided on a joint-by-joint basis.
“Blanket policies result in a lot of technical queries and in some cases the need to compromise on bolt load. Instead you need to do what is best for that specific joint,” Noble says and concludes: “Sometimes it comes down to looking at the application with open eyes, considering how you will actually get the equipment out to the site, the location where it has to be used and how it is going to fit into the application.”
Did you know that…
Friction typically accounts for 90% of the torque applied to the nut during hydraulic torquing?
For bolted joints, several factors must be considered before choosing between torquing or tensioning.