VFB ball-lock-002 The Ball Lock Washer is a hardened washer, which employs the use of hardened steel ball bearings that embed and grip into the flange face and nut bearing surfaces. This mechanical lock begins to occur during the hand tightening stage and is maintained throughout the tightening process. The length of time it takes to assemble a joint is greatly reduced since the operator can quickly maneuver a single tool around the flange. This unique system works both when tightening and loosening. It can be used under the nut, when tightening the head, or used under the head, when tightening the nut. The result is a technology that eliminates the need for a back-up wrench and the need for an operator to place his hands and fingers at risk in a pinch point zone.

The use of back up wrenches accounts for a significant amount of lost time accidents in any industrial bolted joint setting. Pinched and severed fingers are commonly associated with tightening or loosening of a bolted joint. When the hydraulic or pneumatic turning method overcomes the strength or balance of the operator who holds the back-up wrench, the operators’ safety can be compromised. From a reliability standpoint, it is often the case that there is not ample clearance on the backside of the flange to install a back-up wrench. In these cases, the operator typically turns the front nut until enough friction is naturally generated to hold the nut and tighten the fastener. This scenario does not give a high level of assurance that the fastener stress has been created in the joint and can often lead to joint failure and leakage. If a situation exists where the operator cannot access the backside of a flange because of clearance issues, the technology allows the operator to safely and efficiently generate the fastener stress by locking the back nut.

“A Craftsman’s friend, an Engineer’s partner and a Safety Manager’s dream.”
– Lamons

The Torque vs Tension Solution

In the assembly of bolted joints, using torque as a measure of joint tightness has plagued the fastener industry. The Clarkester™ Tester was created to address this mystery.

Errors in target joint clamp load, or bolt tension, of up to 50% may result from using this dated tightening method. We at Valley Forge have worked diligently to create a method to reduce these errors for our customers.

Accurate and reliable bolt tension measurement in the Clarkester™ Tester is assured using Valley Forge’s SPC4™ load indicating system, which can easily be verified for load accuracy.

Capacity

Clarkester™ Testers are available with load capacity up to 250,000 pounds and bolt sizes to 2 1/2”. In addition, torque capacity is considerably higher than that of currently available testers.

Clarkester™ Features

Interchangeable load plates for various head configurations, including hex head, square head and mill liner bolts.
New and replacement parts supplied overnight.
Dependable trouble-free operation without oil and pressure gauges.
Eliminates inaccuracies of out of calibration pressure gauges.
No reaction pins to shear.
Easy and quick calibration of load cell using SPC4™ technology.
Self check calibration ability to verify rebuilt tensioning tools.

With the Clarkester™ Tester, Torque-Tension relationships can be established for most tightening tools including:

Hydraulic torque wrenches
Manual multipliers
Electric and pnuematic multipliers
Impact guns
Torque Wrenches

CLARKESTER™ DEMONSTRATION

TORQUE VS TENSION

The mystery of torque versus tension has forever intrigued the engineers that have tried to apply this method of tightening on fastened assemblies. The engineers have the daunting task of taking into account the condition of the fastener. For example, are the fasteners rusty, clean or lubricated? Will the fastener require lubrication prior to installation? These are only a few of the many possibilities that engineers must be faced with when a critical joint is encountered.

HOW DOES TORQUE RELATE TO TENSION?

The biggest element in this equation is the coefficient of friction of a fastened assembly, or the ‘K’ Factor. Below are a few scenarios depicting a rusty, plain and lubricated fastened assembly.

K Factor:

K = as low as 0.05
Lubed Assembly: Thread and head bearing surfaces covered with high performance lubricants or with anti-seize compounds.

K = 0.10 to 0.15
Additional Lubed Assembly: Additional lubricating coatings of oil, wax or dissimilar plating or hard washer.

K = 0.15 to 0.20
Plain & Clean Assembly: Dry, clean with thin film of oil.

K = as high as 0.35
Combinations of certain materials such as Austenite stainless steel screw/bolts.

Torque (ft-lbs) = Load Required (lbs) * Diameter (in.) * K Factor / 12

HOW THE CLARKESTER™ TESTER WORKS

In order to demonstrate the variability in Torque needed for any critical joint, and how our Clarkester™ Tester can help take the guess work out of this age old mystery, we have calculated the Torque needed for each of the above scenarios.

Lubed Assembly:
T = 30,000lbs * 0.75in. * 0.05 / 12
T = 93.75 ft-lbs

Additional Lubed Assembly:
T = 30,000lbs * 0.75in. * 0.10 / 12
T = 281.25 ft-lbs

Plain & Clean Assembly:
T = 30,000lbs * 0.75in. * 0.15 / 12
T = 281.25 ft-lbs

Rusty Assembly:
T = 30,000lbs * 0.75in. * 0.45 / 12
T = 843.75 ft-lbs

The Maxbolt® is manufactured by inserting extremely accurate and durable load monitoring devices into high quality bolts and studs. The accurate assembly and continuous monitoring capabilities reduce the potential for premature wear, expensive downtime, and catastrophic joint failure. In addition, load-indicating fasteners are compatible with conventional tightening and tensioning equipment and eliminate the need for costly ultrasonic, strain gages, and torque measuring devices.

Now, even inexperienced operators can assemble complex bolted joints with uniform clamp loads within +/-5% of design specification. Because measurements are based on tension, the inaccuracies of torque control are eliminated, ensuring optimum initial conditions before an assembly is placed into service.

The Maxbolt® also provides in-service monitoring, which will warn users of any loosening in order to avoid premature wear, unnecessary downtime, or catastrophic failure. One quick glance is all it takes to check clamp load status. Custom scales can show desired operating ranges using a green zone or pinpoint precise clamp load values. The Maxbolt® Load Indicating System provides the ultimate safety and reliability in a bolted joint. They act as a constant barometer of the integrity of the bolted joint and provide an added degree of protection for workers in hazardous environments. The load-monitoring device is sealed to withstand harsh environments and submersion, with models available to handle temperatures from -40°F to 180°F. At temperatures outside this range, we evaluate the application on a case by case basis.

Our Maxbolt® Load Indicating Fasteners come in various shapes and sizes. They can be manufactured from standard ANSI materials or exotic materials. Each load indicating fastener is calibrated and tested to its proof load to assure that its performance will meet the designed tension requirements of the application. In most cases, load-monitoring cartridges can be retrofitted into customers’ bolts.

The Maxbolt® Knowledge, with its high visibility indicator, capable of being seen at great distances. It not only allows the user to more efficiently see when a bolted joint has lost tension from long distances, but gives you the Knowledge to assess precisely when to re-tighten. This greatly improving safety and making substantial savings in maintenance.

The concept was originally developed for Australian based Woodside Energy to use in their Appleton Cranes. The Maxbolt® Knowledge has taken an already extraordinary product and technology and put it on an even more sophisticated level. With the Knowledge, there are now even more advantages than ever before.

First and foremost, the indicator can be seen from much longer distances due to its increase in size and design, tested at 20 meters (image shown below). Also, the technical design of the white on black allows for superior readability in various lighting circumstances. Furthermore, the continuous scale on the larger indicator allows users to assess the need for tightening on a scaled basis, as opposed the competitions go/no-go design.

This means that the user can easily see the change in load on a custom scale showing desired operating ranges. They can then determine exactly when the need for re-tightening is. This vastly reducing the need for expensive downtime for re-tensioning in great distance applications.

Our Maxbolt® Load Indicating Fasteners come in various shapes and sizes. They can be manufactured from standard ANSI materials or exotic materials. Each load indicating fastener is calibrated and tested to its proof load to assure that its performance will meet the designed tension requirements of the application. In most cases, load-monitoring cartridges can be retrofitted into customers’ bolts.

Below is a VF video on the mysterious topic of Fastener Crosstalk using the Maxbolt®. Enjoy!