Critical joints require controlled bolting throughout their service life to maintain performance, enhance safety, save time, and improve uptime. However, the term is more often applied to installation than to the service life of the bolted joint. Valley Forge & Bolt’s family of load indicating fasteners makes it possible to monitor bolted joints after installation and to always know fastener tension, regardless of the service interval. James Brooks, Valley Forge’s director of engineering, answered some questions about how this innovation can improve controlled bolting programs and ongoing condition monitoring.

What is controlled bolting?
The point of a controlled bolting regimen is to tighten your fasteners to the appropriate tension or clamp load for the application. Typically in controlled bolting, the amount of torque you apply to a given bolt can be roughly correlated to the elongation that you will achieve. For many years, that has been the only way of measuring the elongation, or tension, in the bolt—through the control of torque. But Valley Forge & Bolt has changed that paradigm with its line of load indicating fasteners.

How do load indicating fasteners improve controlled bolting?
We’re taking controlled bolting to a new level because we have technology that enables you to measure the elongation in the bolt without using torque. We have direct tension monitoring in our Maxbolt™ and SPC4™ bolt products. They can tell you in very accurate terms, within +/-5% of minimum yield, what the elongation of your bolt is. Each fastener displays this on a zero-to-100 scale using either a built-in meter, as in Maxbolt™, or with a quick-connect external meter, as in SPC4™.

In many industries, including power gen, we’re now seeing more people coming around to the idea that you can bypass torque and go straight to measuring tension. You’ll still need a method of applying torque, but if you can measure the tension directly, you’re in a much better place in terms of efficiency, safety, and the ongoing health of equipment and processes.

Controlled Bolting Valley Forge

How do load indicating fasteners positively impact the long-term health of machines?
For many years, the term controlled bolting has more often applied to the act of installation rather than to the life cycle of the bolted joint. But the fact is, controlled bolting is just as important after a bolt is installed, and load indicating fasteners make it much easier to maintain bolt tension. Once tension has been achieved at install, there is an inevitable loss of tension that follows. It’s called relaxation. With our products, you can monitor—in real time—the relaxation in the bolt tension. You can literally catch the bolt in the act, so to speak, of loosening. Plus, after you’ve used load indicating fasteners at installation to ascertain appropriate clamp load, you can achieve this load again very quickly. There is no longer a need for cumbersome methods of torqueing and re-torqueing. Simply tighten the bolt and let the tension readout tell you when appropriate tension has been achieved.

How do you use load indicating fasteners for condition monitoring?
Historically, condition monitoring has been the costliest part of controlled bolting. Factors include inspection frequency, accessibility, and equipment downtime, to name just a few. Valley Forge’s SPC4™ Load Indicating Fastener System was specifically created to make ongoing bolt monitoring much easier. It is playing a large part in driving these changes in controlled bolting installation and post-installation thinking.

Once installed, an SPC4™ bolt or stud can be considered as the “foundation” from which a menu of interchangeable inspection options can be chosen. With a standard reading surface across all sizes of bolts or studs, different meters can be used as needed. They include a range of options for virtually any type of plant environment. We have manual snap-on meters, wired electronic meters with data collection and output control for torque-tightening equipment operation, Bluetooth-enabled meters, hardwired remote meters, and wireless meters for remote monitoring that take advantage of standard Wi-Fi. Wireless-compatible SPC4™ meters are easily integrated into a plant’s condition monitoring system for remote readings and in-use monitoring. These options are taking the cost and complexity out of condition monitoring of critical bolted joints. The bolts are now controlled for life.

With Maxbolt™ and SPC4™, any technician at any experience level can achieve accurate, consistent, and repeatable bolting not only at installation, but throughout service life. At maintenance intervals, they will know the accurate tension in seconds, and need only tighten those fasteners that require it.

James Brooks is the Director of Engineering and New Business Development for Valley Forge & Bolt Company. A U.K. native and U.S. resident for over 25 years, his expertise is in solutions-oriented companies from diverse markets such as aerospace, power gen, defense, and fastening. He has more than 10 years of experience in critical bolting, specifically in the field of specialty engineered fastening. He is an engineering graduate from the University of London (U.K.).

About Valley Forge & Bolt
Valley Forge & Bolt Mfg. Co. is a domestic manufacturer of patented bolting products for critical applications. These bolts and studs are widely trusted for their unrivaled quality, extraordinary performance, and enduring reliability. Email: Call: 1 (602) 269-5748. On the web: