Valley Forge SPC4™ Load-Indicating Technology: The Most Accurate Method of Measuring Bolted Joint Tension

protection plan for big equipment

Proprietary technology interprets clamp load within bolts, provides remote monitoring capability

Knowing the tension of critical joints is a matter of safety, peak performance, and maximum uptime. Valley Forge & Bolt is shifting the paradigm with SPC4™ Load-Indicating Technology that makes it possible to measure the actual tension in a fastener, not just the preload that is being applied by torque or tension tools. By using SPC4™ and any one of its specially designed interchangeable readers, technicians can quickly and easily gauge tension and even have the option of remotely monitoring fastener tension within SPC4™ bolted joints.

Around the globe, SPC4™ solves complex bolting issues in mining, oil and gas, refining, nuclear, power generation, rail, crane, steel mill, military, and subsea industries.

SPC4™ is proprietary technology from Valley Forge that is ASTM F2482 compliant and accurately measures direct tension in the fastener within +/- 5%. It provides absolute, real-time knowledge of fastener tension and performance—from installation through fastener life.

SPC4™ measures the stretch of the bolt (in other words, the bolt tension), directly from the fastener. Because stretch is the force that creates clamp load, this capability makes SPC4™ the most accurate method available to monitor the clamp load of critical joints.

With SPC4™, virtually any technician can use any type of tightening tool—hydraulic, pneumatic, electric, or a hand wrench—and still achieve even and optimal load on a bolted joint. SPC4™ can measure preload in the fastener at installation, monitor load while in service, or measure load and load loss during maintenance inspections. The result is optimal joint integrity, less downtime, and safe performance of equipment.

Valley Forge engineers and manufactures a variety of SPC4™ readers in analog and electronic formats to suit any application and any budget. Technicians simply quick-connect the reader to a datum disc on the end of the SPC4™ fastener, and the tension is displayed in real time on the reader as a percentage of minimal yield strength. Any reader can be used with any SPC4™ fastener. Electronic readers, offered in both wired and wireless configurations, provide digital and Bluetooth output, installation tool control, and load data recording systems. Wireless readers allows for real-time remote load monitoring and include Wi-Fi and low frequency options.

SPC4™ technology is available in standard bolts, studs, custom designs, and retrofits for customer-supplied fasteners, each modified with Valley Forge’s exclusive datum disc and gauge pin compatible with any Valley Forge-supplied reader. Save time and money, improve safety and performance, and increase the speed and repeatability of accurate installation of bolted joints. To learn more, visit