First published in Bolted #2 2017.
You first worked with Superbolt tensioners at Diablo Dam in 1984. How did that come about?
“I was a machinist working at Seattle City Light, the electric utility for Seattle. We worked out of the machine shop down there, and we would go up and be labour support at Diablo Dam. In 1984, they were doing a stator-rotor inspection on the turbine, so they had to remove the rotor; that involves taking the thrust bearing apart, which is mounted on the turbine shaft. It is very important that the thrust block is perpendicular to the shaft within less than one-thousandth of an inch. Otherwise, it will have run-out and wobble.”
How did the Superbolt tensioners help with that?
“Back then, to get the right tension in the bolts, you had to heat the bolts so they would elongate, do the installation, and then wait for them to cool overnight. If the thrust bearing wasn’t sitting right on top of the shaft, you had to do it all over.
“The engineers at Diablo Dam had been in contact with Superbolt, and they modified the bolts so you didn’t have to go through this long process. Instead, we could tighten up those little bolts. If the thrust bearing wasn’t exactly perpendicular, you just tweaked the bolts on the opposite side. It was a very labour-saving modification.”
Today, you work at Wells Dam. What do you do there?
“I’ve been with the Wells Hydroelectric Project for about 17 years, managing and monitoring the project. What I’ve always enjoyed about my work is that every day there are new challenges or something that you’ve got to fix. We’ve got air systems, electrical systems, mechanical systems, hydraulic systems – all these different auxiliary systems that feed the turbines that run 24 hours a day.”
How has the dam been modernized over the years?
“One of the ways that it has been modernized is that we have installed PLCs on the majority of our alarm systems. Today, we have over 2,500 alarm points on different systems. This allows us to set more parameters for the alarm points, and we can also trend over time and compare with different machines. If something is starting to fail, you can set up a parameter to get an alarm so you can look into it before the failure actually happens.
“We are also using Superbolt tensioners when rebuilding our turbines. They’re being used in the load screws that hold the turbine bearing shoes in place, and in our turbine’s outer head cover, where you can’t access the bolts with a big wrench because it’s close quarters. They’re very reliable.”
FACTS: MIKE BRUNO
TITLE: Project Superintendent, Wells Hydroelectric Project, Douglas County Public Utility district
LIVES: Chelan, Washington
BACKGROUND: Has a degree in industrial technology from Shoreline College; also studied at Cogswell College. Worked at Seattle City Light as a hydro machinist and foreman until 1990, then as a mechanical supervisor for the Skagit River Hydroelectric Project until 2000. Since then with Wells Hydroelectric Project.
PASSION: Married with three grown daughters, two granddaughters. Enjoys bow hunting and playing golf.
First published in Bolted #2 2017.
SAFETY. The JFE Steel Corporation’s West Japan Works is one of the largest and most advanced steel mills in the world. Like all steel plants, the operating conditions are exceptionally demanding on machines and equipment, and potentially hazardous for personnel – especially the hot rolling mill, where molten steel is flattened and stretched into thin sheets. The temperature of the steel will reach at least 450°C (842°F).
Until recently, the fasteners that connected the decelerators and pinion stands on the hot rolling mill, were tightened using a 300-kg weight, which was suspended from the ceiling via a crane. The weight would be pulled from a makeshift scaffold, before letting it hit the wrench like a hammer. Overall, the procedure involved five people: three to pull the weight, one to fasten the wrench, and one to operate the crane. It took an hour to tighten each bolt, and the multiple safety risks for the personnel involved were considerable.
Switching to Superbolt multi-jack tensioners has turned one of the riskiest maintenance tasks in the plant into one of the safest. Each connection can now be secured by one person in just 15 minutes. With eight bolts on each mounted application, the overall reduction in downtime and increase in productivity is significant.
In fact, Superbolt multi-jack tensioners have proven so successful that they have been implemented in JFE Steel’s other hot rolling mills in Fukuyama and Chita.
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 #1 2017.
Q: How does lubrication affect hydraulic tensioning and multi-jackbolt tensioning?
A: With the traditional method of tightening a nut, using a spanner, lubrication is very important, as there are a lot of surfaces moving against each other – the threads of the nut against the threads of the stud and the underside of the nut against the surface of the joint. Overcoming these frictional forces accounts for approximately 90 percent of the work (energy input) applied to generating the load in the joint.
When a hydraulic tensioning tool applies a clamping load to a joint, lubrication has no effect as it is applied directly to the stud and joint. A tension force is a linear force applied in an axial direction, so there is no rotation required to generate the load. This allows the nut to be turned down against the joint face under minimal friction.
As there is no friction to consider, there is no need to reduce the coefficient of friction using lubrication. Also, the lack of friction in the application permits much more accurate and repeatable results.
With multi-jackbolt tensioners (MJTs), the use of a lubricant on the main bolt thread does not affect the preload. It is advisable to use a very light film of lubricant with anti-seize characteristics to facilitate tensioner removal.
A more tangible effect of lubrication for MJTs is from the required lubricant use on the individual jackbolt threads, jackbolt bottoms of the tensioner, and washer face.
Proper use of lubrication is crucial to safeguarding repeatable and precise preload control in Superbolt installations. Superbolt mainly uses a graphite-based lubricant with a low friction coefficient and steady performance to achieve a positive impact on the preload. The MJTs are delivered with lubricant pre-applied to the installed jackbolts. Additional lubricant is included for application to the jackbolt bottoms. For subsequent installations, reapplication of lubricant is required to provide the intended performance.
First published in Bolted #1 2017.
ENERGY. With oceans covering more than 70 per cent of the earth’s surface, wave power is potentially a huge untapped source of renewable energy. The problem is that most wave energy converters are too large and costly to be commercially viable. Swedish company CorPower Ocean could have the answer.
The company’s compact Wave Energy Converter works by oscillating in resonance with waves, amplifying their motion and then converting that energy into power. CorPower Ocean founder, cardiologist Stig Lundbäck, invented the initial concept based on the pumping principles of the human heart. In the same way that a heart uses hydraulically stored energy to form back in place, the Wave Energy Converter uses a pneumatic pre-tension system to pull down the buoy after it has been lifted by a wave.
This allows for a relatively small device to harvest a large amount of energy. It is estimated that one buoy, eight metres in diameter, can generate around 250 kilowatts of power. That is enough electricity for around 200 homes.
“If you look at wave energy potential, somewhere between 10 to 20 percent of global electricity consumption could be provided by wave power,” says Patrik Möller, CEO, CorPower Ocean. “It has the potential to become the most competitive source of renewable energy. It offers five times more energy density than wind and ten times more than solar power. Waves have fewer variations and are more predictable than sun and wind, so you know a few days in advance what the energy flow will be.”
Currently, the Wave Energy Converter is undergoing tests with simulated wave loading, while a full-scale demonstration is being set up to begin in 2017. One of the key challenges has been keeping the buoy small and lightweight, while at the same time strong and durable enough to survive the toughest storms at sea.
This has presented a number of fastening challenges. On the mainframe inside the buoy, CorPower Ocean has elected to use Superbolt tensioners due to their lower torque requirements compared to a single bolt, which makes assembly far more manageable. Superbolt can also guarantee reliability over the buoy’s intended 20-year lifespan. At the base of the buoy, Nord-Lock washers are used, since they can maintain the correct tension over many load cycles over a long period of time.
First published in Bolted #2 2016.
Bolted joints are a key component of most machines, which make them essential to many of Japanese Sodick Corporation’s applications. The company manufactures industrial machines and machining tools as well as consumables and other products. Original research and development is a top priority, ensuring high-quality products that improve the customers’ manufacturing operations.
Sodick moulding machine engineers recently attended a seminar on solutions to the problem of loose bolts held by Ikeda Metals, a Nord-Lock Japan distributor. It touched upon exactly what they were struggling with.
Together with Ikeda Metals engineers, Nord-Lock engineers started searching for areas where they could help improve Sodick’s bolted joint design. They realized that in the Sodick moulding machines, the tie rod bolts were tightened by a traditional method. Tie rods are quite long, so if they are subject to torsion stress, and the machine is operating for a long time at the end-customer site, it is difficult to guarantee optimal performance. From the customer’s perspective, the ability to properly control the force on the joints becomes essential, because it is key to safe operation without costly downtime.
Superbolt was the perfect solution as it just has pure tension. It does not create any friction and therefore can control the force on the joints without giving off torsion stress. The people at Sodick were impressed by how diligently the Nord-Lock engineers worked at finding solutions that catered specifically to their application needs.
Superbolt tensioners are premium products and while there are cheaper alternatives in the market, Sodick firmly believes that the cost performance of the product makes it appealing. About half of Sodick’s products are sold overseas, and some big machines cannot be shipped assembled. It is essential that the moulding machine assembly and changing of parts can be carried out easily, quickly and safely at the end-customer site. Sodick is pleased to hear reports that their customers are satisfied with having smooth, speedy operations.
First published in Bolted #2 2016.
Customer: Ampegon Antenna Systems
Application: Gearbox in rotatable antenna
End customer: British Broadcasting Corporation (BBC)
Location: BBC Radio Transmitting Station, A’Seela, Oman
Product used: Superbolt CY-M36 x 4/W multi-jackbolt tensioners
Nord-Lock Superbolt tensioners came to the rescue when a windstorm damaged a broadcasting antenna structure in the Oman desert. German company Ampegon Antenna Systems were responsible for fixing the drive of a rotatable antenna, which is owned by the BBC.
Ampegon have over fifty years experience in providing high-performance antenna and mast systems for radio broadcasting. Their speciality is a rotatable short wave antenna system with a steel structure weight of 200 tonnes. One of these 80 metres high and 80 metres wide structures was installed on the BBC facility in Oman in 2000. In June 2010, a cyclone destroyed one of the gearwheels in the rotatable joint, which facilitates the rotation of one of the upper parts of the structure.
The antenna is an important part of the BBC’s broadcasting capabilities in Oman, allowing worldwide radio transmissions. However, a quick fix was to be delayed by lengthy legal and budgetary discussions. After finally starting the repairs, Ampegon looked to a solution for pre-tensioning the bolts, fixing the gearboxes to the tubular shaft without the temporary import of hydraulic tensioning equipment. It was then that they turned to Nord-Lock in Switzerland, who supplied Superbolt CY-M36x4/W multi-jackbolt tensioners. These were installed into replacement gearboxes at the site in May 2015.
According to Christoph Fischer, Ampegon’s Project Manager in Oman, the BBC are extremely happy with the Superbolt solution. “It was a complicated process to lift the gearboxes out of the steel tower and replace them. However, the Superbolt tensioners are high strength, reliable and were easy to install. The results of the project have been to everyone’s satisfaction.”
The September issue of Bolted magazine is out now! Prepare yourself on a reading journey to explore interesting cases and insights from the world of bolt securing.
In this issue, our theme article focuses on coupling challenges. Couplings are essential in the power generation and shipping industries, and are arguably the most demanding of all bolting applications. Learn what the bolting experts have to say about couplings.
Engineers from the Nord-Lock Group answer questions on how to get the most out of your fasteners and cover the key advantages of hydraulic tensioning.
We witness the largest public works project in California’s history, where Boltight tensioners are installed on the San Francisco-Oakland Bay Bridge. We then move on to Oman to find out how broadcasting antennas owned by the BBC are being secured against windstorms. Last but not least, we ride on the time machine as we simulate 20 years of wear and tear on a wind turbine in just a fraction of that time.
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