Designed with the benefit of more than 30 years experience in the field, Boltight has created a range of tools to meet the challenge of today’s bolt tensioning requirements.
Just watch how easy it is to install these tensioners!
First published in Bolted #2 2017.
SUPERBOLT has its origins in the US steel industry and has been providing a wide range of bolting innovations for a variety of industries since the 1970s. Its ongoing success within Nord-Lock Group’s portfolio is based on a knowledge of customer challenges and a commitment to supplying practical solutions to the market.
Launched in December 2016, HyFit and VersaTite tensioners continue Superbolt’s tradition of versatility. Superbolt multi-jackbolt tensioners have been on the market since 1984, allowing bolted joints to be tightened mechanically, without specialized skills or heavy tooling. HyFit is hydraulically actuated, while VersaTite uses both mechanical and hydraulic tightening. Easy to fit and remove, they are offering safe and efficient operations and increased uptime to customers worldwide.
“To have both mechanical and hydraulic options is a huge advantage in many industries,” says Steve Brown, Global Product Manager, Expansion Bolts. “HyFit is ideally suited for use on high-speed couplings on gas and steam turbines, and on marine propulsion drives. Traditionally fitted bolts must have a close tolerance. The fitting and removal of these are often problematic and can lead to damage of the couplings and costly downtime for customers.”
Both HyFit and EzFit (previously named EB, mechanical Expansion Bolt), are designed to offer a simple easy-to-fit solution that, once tightened, will provide a long and reliable lifespan.
VersaTite, as the name suggests, is a versatile tensioner that allows customers the flexibility of both hydraulic and mechanical tensioning and removal. Combining the speed of hydraulic tensioners and the accuracy of the Superbolt mechanical variant, it has been developed to improve operations in several industries since its launch at the Power-Gen International show in December 2016. “This type of ‘all-in-one’ technology represents the next step for Nord-Lock Group in terms of providing the market with a new generation of bolting solutions,” Brown says.
First published in Bolted #2 2017.
Any machine with moving pivots will eventually experience lug wear. The most common are applications subjected to heavy loads and vibrations, such as mining and construction equipment. Other common applications include industrial presses, wind turbines and moveable bridges. Any moving pivot in just about any application will experience lug wear at some point – the higher the demands, the faster the onset. When it happens, it will lead to a loss of precision and control.
There are three main reasons why lug wear is inevitable when using conventional straight pins:
The most common solution to lug wear is to repair the lugs with welding and line boring. The first step of this is to unload the pivot and dismount the pin. Then the line boring equipment needs to be lined up and “mounted” to the equipment. The worn lugs are rebored, filled up with weld, and finally rebored with a fine cut to the original diameter and tolerance. After removing the line boring equipment and repainting the lugs, a new replacement pin is installed. This whole process can take anywhere from a few hours to a few days, depending on the size and complexity of the installation. During this time, the machine is inoperable.
Despite the time and costs, this method is generally accepted as unavoidable. “It’s just something everybody does because everybody else does it, and they’re not even aware that there is another way,” says Jonny Wiberg, development & research engineer, Expander System. “Repairs are just accepted, and people don’t even look for another solution.”
Over the years, engineers have searched for better solutions to the lug wear problem. None of the previous attempts has proven universally effective. One option is to use a pin that fits as tightly as possible into the lug’s holes, practically eliminating the play between the two, and ensuring the best possible pressure distribution for a straight pin. Not only does this make the pivot expensive and the pin difficult to mount; over time, the lug hole will expand anyway.
Using the temperature method, the pin is frozen and then allowed to get warmer and expand once installed, creating a perfect press fit in the lugs. Tolerances of both pin and lugs need to be exceptionally tight – down to some hundredth of a millimetre, or tolerance grade 6. This significantly increases the cost of the pivot. Pivots with frozen axles are often considered maintenance-free, but they are impossible to maintain, as the axle can’t be removed.
Another solution is to improve the strength of the lugs with bushings. However, this will only prolong the onset of lug wear, and will not eliminate the problem completely, as the bushings need to be replaced several times during the equipment’s lifetime.
None of these solutions will completely remove the need for costly and time-consuming lug repairs. In contrast, the Expander System can potentially eliminate lug wear once and for all. It works by using a pin with tapered ends and expanding sleeves on each side. When it is installed, the sleeves expand radially, so that they fill the lug to create an exact press fit.
As the sleeves of the Expander System expand into the lug, they can take up unevenness or deformation, eliminating the need for welding and line boring. This significantly reduces the time needed for installation as well as the machine downtime. The most time-consuming process for installing the Expander System is the dismantling and removal of the original pin – a process that is also necessary before welding and line boring. In a recent example, the Swedish Expander System company was asked to do a cost comparison for a 70-millimetres axle. Considering the cost of the expansion bolt, the cost of pin removal and installation, plus the income loss from downtime, the total cost of the Expander System solution was calculated at around 500 euros. A conventional pin was around a third of the purchase price, while the costs of removal and installation remained the same. The time needed for line boring, in addition to the time taken for the transportation of line boring equipment, and the loss of income from significantly higher downtime, all contributed to a total cost estimation of over 2,300 euros.
Using the Expander System will not totally eliminate the need for boring, but for the welding process. It will eliminate the lug wear problem for the lifetime of that pivot. Using conventional pins, lug wear would inevitably return and the repair procedure would need to be repeated. In a typical application, this happens three to four times during a machine’s lifetime or every 3,000 or 4,000 hours. This means that the cost savings can amount to thousands of euros – for each machine.
How a rusty nail led to an award-winning innovation
In the 1950s, twin brothers Everth and Gerhard Svensson were building roads throughout Sweden, and becoming increasingly frustrated with the downtime and repairs caused by lug wear. One day, when a pivot pin was coming loose, Everth improvised and took an old rusty nail to fix the pin in the lug hole.
As a temporary solution, the rusty nail worked quite well and inspired Everth to develop the Expander System. For many years, the twin brothers used expander products as they continued to build roads. However, it wasn’t until 1986, when Everth’s son Roger realized the ingenuity of his father’s solution, that the concept was patented and the company Expander System Sweden AB was founded. In 1987, the Swedish Minister of Industry awarded the Expander System with the Innovation Development Award, in memory of Alfred Nobel. Today, the Expander System is installed in millions of machine joints globally.
Getting over 6,000 extra operating hours
Lug wear is a widespread problem for machinery pivots. It has cost users of machinery lots of money through the years – for repairs as well as for downtime. This is something that the Expander System can put an end to.
The Expander System will in most cases cost more than a traditional straight pin. But when all costs are fully calculated, including the time and costs associated with welding and line boring, and the loss of production due to downtime, the Expander System will prove to be significantly more cost-effective. The full extent of savings depends on many different variables, but it is fair to say that the higher the frequency of lug wear and the higher the costs of downtime, the greater the potential savings.
For Swedish construction machine supplier Maskinia AB, every minute of downtime for machine repairs means lost income. This is why they have been using the Expander System since 1999.
Recently, an excavator was brought in for repairs after 3,700 hours of operation. Using the Expander System, the boom mounting axle was replaced in just 6 hours. By contrast, the repair would have taken 3–4 days if it was replaced by a traditional pin, using the common method of welding and line boring.
Lars Malmén, Aftermarket Manager at Maskinia, says that, “The Expander System admittedly costs more than a traditional axle, but if you include repair time and stoppages with loss of income, the difference is clearly to the advantage of the Expander System. If you add the fact that Expander offers a 10-year function warranty, you can count on at least 10,000 problem-free operating hours – compared with the 3,700 that is regarded as normal for a traditional pin.”
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.
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.
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.
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.
Boltight’s Typhoon range of bolt tensioners offer a high-load, low profile solution for space-restricted applications that demand high and accurate preloads. A solution widely used within the Wind industry where such space-restricted connections are common. Additional convenience features such as a spring loaded gear drive for nut rotation and automatic piston retraction, ensure that Typhoon bolt tensioners are the ideal choice for any application demanding a powerful, portable and user-friendly bolt tensioning tool.
Boltight’s Piston Retraction system takes the hard work out of resetting bolt tensioner piston stroke. Depending on the design of the tensioner, the pump will give automatic piston retraction or assisted piston retraction.
Quick and easy, it saves operation time, reduces operator fatigue, and promotes safe and efficient working practice.