Web-based clamp load sensor is IoT-compatible


Phoenix—Dec. 4, 2020—Maintenance engineers in critical environments charged with condition monitoring have long wished the bolts themselves could start the conversation. Now they can. Valley Forge & Bolt has taken their SPC4 ® Load Indicating Technology to a new level with the latest addition to the company’s RTM (Remote Tension Monitoring) series of meters—the UHF Band RTM Meter, a wireless bolt monitoring system.  The UHF Band RTM Meter operates in 433/868/915 MHz frequencies, which includes the industrial, scientific and medical (ISM) frequency.UHF Band RTM Meter

This wireless sensor detects and collects the tension level in a bolted joint as read by the company’s SPC4® fastener, and then relays the data to a facility’s condition monitoring/SCADA system. Users can also program the sensor to take measurements at prescribed intervals and send alerts if a bolted joint falls out of chosen tension parameters.

There are several scenarios in which the UHF Band RTMMeter’s capabilities will pay dividends for users, but the first is the meter facilitates close monitoring of new fasteners during and immediately after install. The early hours after an initial tightening sequence can be critical to long-term performance because an unexpected loss of tension can affect bolt life.

“The facility manager can set the reading intervals for rapid readings, down to once every second, or for every 10 minutes. He or she can see immediately if a fastener is losing tension and correct it,” said James Brooks, Valley Forge & Bolt’s head of engineering and business development. “Conversely, after enough time has passed and they are satisfied that the tension is holding, the manager can quickly and remotely adjust the reading intervals to be farther apart.”

In the long term, all bolts can be set to broadcast alerts when a chosen tension threshold is crossed.

“Select a tension percentage that is close to your application’s danger or alert zone,” said Brooks. “If needed, a window with upper and lower tension percentage limits can be created. An alert can be sent as an email or as an audible alarm. The user has total flexibility.”

For the first time, the bolt is starting the conversation about whether it needs maintenance or inspection. Managers can also program alert windows during “interest” periods, such as times of suspected greater vibration in a process, to gauge how fasteners are reacting.

With a web-based user interface, users can change parameters for each wireless sensor remotely. “These features have never before been available in a bolting wireless product,” said Brooks. “The UHF Band RTMMeter is a game changer.”

In addition, the UHF band attribute will improve battery life and enable increased distance from the probe to the collection device. SPC4® fasteners make it possible to measure the actual tension from within a fastener, providing real-time knowledge of critical joint tension and performance from installation through fastener life. A variety of sensors and meters are available to read, display, and relay this tension information.

Innovative new liner bolts can be seated more securely, prolonging equipment life

Mill SealWithin every ore grinding mill is a slurry that is essential to its processes. However, unconstrained, this mix of water and grit becomes the enemy of the very mill designed to hold it.

When bolts are not properly tensioned, mill liners become loose, and the slurry works its way into the bolt pocket. Eventually, the abrasive slurry leaching into the bolt pocket can result in bolt erosion, causing premature failure of both the bolts and the mill shell.

The problem with typical liner bolts is their geometry.

In conventional liners, the oval radius of the bolt is 1/8-inch per side smaller than the oval radius of the liner. The resulting angularity deviation between the liner bolt pocket and bolt creates two high-stress points of contact. This poor interface becomes an issue the moment the mill goes into service, eventually causing premature failure that can require a total shutdown in order to tighten loose bolts or replace broken liners.

Valley Forge & Bolt has developed a liner bolt innovation to improve the reliability of mill liners and liner bolts in ore grinding mill applications. The Sealing Mill Liner Bolt is designed with a polymer sealing ring that conforms to the liner bolt pocket, eliminating gaps and stress points.Mill Liner

“The head shape with the seal conforms to the liner pocket for better fit, so the bolts only need to be re-torqued once,” said Brooks. “The seals also help absorb heavy impacts and reduce the bolts’ chances to loosen.”

The Sealing Mill Liner Bolts produce effective sealing of the bolt to liner pocket throughout the full range of bolt capacity, including during very low loading conditions. Sealing Mill Liner Bolts, as well as the company’s companion product, Sealing Mill Ridgeback® Liner Bolts, hold liners more securely than conventional liner bolts.

“Both the Sealing Mill Liner Bolts’ and Sealing Mill Ridgeback® Bolts’ heads increase contact surface by conforming to the shape of the tapered surface of the pocket. This eliminates points of stress and, with that, problems common to ore grinding mills,” said Brooks. “It gives mines an economical way to maximize the life of their bolts and help prevent expensive unplanned shutdowns.”

For more information, email sales@vfbolts.com or call: 1 (602) 269-5748.

New SPC4™ meter from Valley Forge is designed with mining in mind

To outside eyes, mining’s twin objectives of worker safety and maximum productivity can seemingly be at odds, but that’s never really the case. The truth is, ongoing technological developments consistently improve both. The latest product from Valley Forge & Bolt, a domestic manufacturer of patented bolting products for critical applications, offers a prime example of a manufacturer committing to helping mines perform more efficiently while improving safety.406A

The new product is the latest meter for its SPC4™ Load Verifying System. The SPC4™ 406A Electronic Meter (VF# SPC4-ASM-406A) is specially designed for accurate performance in heat, humidity, and other demanding environments found in mining. By taking into account mining’s unique environmental factors, the meter works as part of the company’s SPC4™ system to provide to provide accurate clamp load data for critical bolted joints, which leads to a full spectrum of aggregate benefits for total mine operations.

The SPC4™ system encompasses fasteners equipped with Valley Forge load-indicating technology, along with a wide variety of meters to fit a range of applications and environmental conditions. The meters, including analog, digital or Wi-Fi versions, measure tension directly from within the fastener to +/- 5% accuracy. The 406A meter joins this complete offering.

In total, the SPC4™ system directly measures fastener tension to provide the most accurate data possible about the actual load within critical bolted joints. In the field, this information is used to make both installation and maintenance faster and more accurate, create more effective maintenance schedules, and give crucial, early insight into fastener and equipment behavior that might lead to premature failure, allowing it to be corrected before problems arise. The net gain is increased productivity, performance, and safety combined with savings of time and money.

The 406A meter’s prototype was field tested on flange joints in Houston, Texas, and is already in use in mines in South America. It boasts a rugged design with a shock-resistant casing that is IP54-rated for protection against dust and particles. Its internals are specifically engineered to deliver high performance that is unaffected by extreme heat and humidity.

“With the 406A, our aim was to create a meter with the extra durability mining environments need while still maintaining the high degree of accuracy people expect from Valley Forge,” said James Brooks, Valley Forge & Bolt’s director of engineering and new business development.

In addition to these crucial performance factors, the 406A has other features designed with the mine in mind. The ergonomic handheld design was built for ease-of-use in the field. The one-touch operation with a large, visible button is easy to engage without removing PPE gloves, and its large digital display allows for easy reading.

Bluetooth compatibility provides scalability for remote data monitoring and data logging capability. This opens up even more maintenance planning options, as it creates an ongoing record of fastener load changes across a mine’s critical joints. The gathered information provides insight into changes in clamp load, and these data points allow for smarter and more predictable equipment maintenance over time.

“SPC4™ technology has been embraced by customers throughout the mining industry for its accuracy and reliability,” said Brooks. “The 406A meter now becomes the leading choice for mining operations that use handheld meters with their SPC4™ fasteners.”

As the world continues to navigate through the COVID-19 pandemic, Valley Forge would like to provide an update regarding our employees, facility and our continued ability to fulfill our customers’ orders.

All parts manufactured at Valley Forge are made with U.S. domestic steel and our raw material supply for this and other materials/components remains strong and unaffected. We have not experienced any disruptions in our supply chain and have increased our inventory of raw materials. Additionally, through continued best manufacturing procedures and innovations, we have managed to reduce lead times to 4 weeks on standard parts.

In compliance with state-mandated precautions, we are continuing to wear masks, wash hands, physical distance, have daily temperature checks and limited group sizes to no more than 5 employees. We have also instituted additional cleaning and sanitizing of common areas, restricted onsite visits, suspended sales travel to customer locations and have tested 100% of our employee base for the virus with some being tested multiple times.

We have had numerous calls with customers through electronic video conferencing platforms including Zoom, TEAMS and Skype and have established those same means of conducting our internal meetings. If this is something your team can benefit from, please contact us at Sales@VFBolts.com. 

Together, we will continue to move through this trying time and continue to meet 100% of your bolting needs.

Wishing health and safety to you, your families and your employees.

Michele Clarke

Chief Executive Officer

What if you bought a mine and 6,000 bolts were improperly tensioned?

Buying a mine with an unknown maintenance history and a multitude of bolts showing signs of improper tension is a worst-case scenario. Yet even in this situation, load indicating fasteners can still save big money and thousands of man hours. A mine operator in Latin America made this discovery when it purchased such a mine. Inexplicably, the previous owner had neglected its mills, and nearly every bolt was not tensioned to the correct design load. However, as luck would have it, the mills were entirely outfitted with SPC4 Load Indicating Fasteners from Valley Forge & Bolt.

Tackling troubleSPC4

The first hint of trouble? Bolts were loose in their joints, at 0% tension. The mine was running two processing lines, each with one SAG mill and two ball mills, for a total of six mills. With each mill containing approximately 1,000 bolts, there were 6,000 bolts that needed to be checked. It was a monumental task.

The mine’s new owner reached out to Protorq, Latin America’s premier distributor and installer of Valley Forge SPC4 and other fastener products. In the face of a seemingly impossible situation, the one saving grace was the presence of the SPC4 Load Indicating Fasteners, which opened up a range of time- and money-saving options that simply would not have been possible with any other type of bolt.

SPC4 fasteners contain proprietary technology that measures tension as a percentage of minimum yield from directly inside the bolt. The information is relayed from a datum disc on one end of the bolt to a variety of Valley Forge meters and displayed in an easy-to-read digital or mechanical format.

“With SPC4, it couldn’t be any easier to check fastener tension,” said Bret Halley, chief operating officer of Valley Forge. “The previous mine owners simply weren’t using the technology and capabilities that were right in front of them.”

Protorq crews used the SPC4 meters to ascertain the load of each of the 6,000 bolts across the six mills. The wide range of load percentage was staggering—from bolts hanging loose at 0% all the way to significantly over-tensioned bolts well over 100% of minimum yield strength. Protorq was directed to replace the over-tensioned bolts, as the mine operator had determined the over-tensioning had compromised the bolts’ integrity. In all, 100 bolts had to be completely replaced. Under-tensioned bolts were simply re-tensioned to the correct load using the SPC4 meters.

Ultrasonic testing not an option

What if the same scenario had existed, but with standard bolts rather than SPC4? Some might believe that ultrasonic testing would have been an equally easy solution. The fault in that thinking is this: There were no baseline measurements recorded by the previous owner after the bolts’ initial installation. As a result, Protorq’s crews would have needed to first remove and then re-install or replace all 6,000 bolts to recreate this baseline measurement. Conversely, the SPC4 system allowed them to replace only the 100 bolts that were over-tensioned, saving hundreds of maintenance hours.

SPC4’s immediate and ongoing benefits

Protorq’s 30-man crew spent 35 days, spread over several months, to completely rehab the six mills. Protorq’s general manager, Gonzalo Diaz, estimates that without SPC4 it would have taken three times as long. “Without SPC4 technology, this easily would have been a 100-day undertaking,” said Diaz. Multiply each additional day by 30 crew members, and it’s easy to see how the man hours saved would stack up quickly.Mine crew

SPC4 also comes with other benefits for mines and their mills. The Model 600A digital meter, which was left with the mine on completion of the rehab project, features data-logging capabilities. Tension data collected from the SPC4 fasteners can be uploaded to mine computers to develop a clear picture of vibration hotspots. The meter also creates an automatic record of tension data at install or re-tensioning, so the mine will never again be without this information.

Another meter type, Model 702-02, works wirelessly and incorporates bolt tension information into existing condition-monitoring systems. Wireless meters send scheduled, periodic data reports to the central system, offering in-situ load readings of critical joints. Maintenance managers become familiar with bolt activity by recognizing patterns in the changes to bolt tension, signaling that the joint is in need of attention. This insight could prevent costly bolt failures and time-consuming unplanned maintenance downtime.

Preserving a multimillion dollar investment

Halley points out another advantage. “Properly tensioned bolts prevent slurry ingress into a mill’s critical joints. Once slurry gets in, it becomes a permanent issue over the life of the mill. It can lead to chronic bolt failure.” He describes the exponential growth that starts with a small cluster of just a few bolts that fail, which quickly becomes 10 bolts, then 20, and so on.

This is significant, since mills are in service for an average of 30 years. Using SPC4 Load Indicating Fasteners from the beginning, and using them properly, can reduce this risk, which saves incalculable time and money over the life cycle of the mill. “Not only that, it protects a multimillion-dollar investment in that mill,” Halley said.

Diaz, Protorq’s general manager, says that mine owners not properly taking care of equipment is, unfortunately, a larger problem than one might imagine. “The results are often catastrophic,” said Diaz. “Luckily in this case, we had SPC4. That made all the difference in allowing us to tackle the problems in a timely manner and bring the mills back to health.”

Failing flanges saved by extra-long load-indicating fasteners


A mining operation is only as good as its ball mills, which a precious metals mine in British Columbia, Canada, discovered the hard way. A simple disruption in the mating of flanges in the ball mill was causing tens of thousands of dollars in losses on a weekly basis. It took a new kind of fastener, and a manufacturer with an innate understanding of bolting technology, to remedy the problem.

With the flanges not mating properly, bolt breakages in the mill were occurring on nearly a daily basis. Bolt changeouts typically lasted four hours, at a cost of $9,000 per hour in lost production. Multiple outages costing roughly $36,000 each occurred every week, adding up quickly. Not to mention they’d been going on for two years.SPC4

On top of the high price of bolt replacement, the mine was also losing money in the form of restart costs. The power drain associated with restarting the motors on four 12,000-horsepower mills sent hydro costs skyrocketing.

Mine maintenance engineers tried a number of potential fixes, but nothing worked. They contacted several different fastener companies, with no resolution–until they reached out to Valley Forge & Bolt, maker of fasteners with Load Indicating Technology. Valley Forge engineers took careful measurements of the troublesome mills and their flanges and extensively studied the various strains to which the mills were being subjected.

After reviewing the results, Valley Forge engineers determined the mill’s maintenance staff needed a method of monitoring bolt tension so they would have some warning of emerging issues. Engineers also wanted to extend the grip length of bolts used in the ball mills.

Valley Forge engineers specified the company’s exclusive SPC4™ Bolts with Load Indicating Technology for the application. SPC4 bolts have built-in load indicators that measure bolt load from directly inside the bolted joint. A datum disc on the end of each bolt translates this information and relays it to digital meters, where it is displayed as a percentage of load. The result is an easily readable numerical display that measures actual tension within the fastener, accurate to within +/-5%.

Now, rather than relying on far less accurate torque-to-tension conversion formulas, mine maintenance staff can monitor critical joints and be aware of tension loss well before catastrophic failure.

In addition to including Load Indicating Technology, Valley Forge specified extra-long bolts for the mine. The company supplied 17-inch bolts, rather than 13-inch, and dual 2-inch sleeves to be used with each bolt. The rationale behind the recommendation is that, for given service loads in the joints, bolts with the longer grip lengths will be more forgiving to flange separation caused by mill charge movement. The longer bolts increased the grip length of each joint by nearly 40%, from 10.5 inches to 14.5 inches.

According to the mill’s maintenance manager, “Valley Forge & Bolt instructed us in the fine art of bolting technology. I didn’t think I could ever learn this much about bolts.” By the mine management’s own estimation, changing to the Valley Forge SPC4 Bolts with Load Indicating Technology saved them $20 million.