Knowing the tension of critical joints is essential to safety, performance and maximizing uptime. SPC4 load-indicating technology (photo) 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 gage tension and even have the option of remotely monitoring fastener tension within SPC4 bolted joints. SPC4 is ASTM F2482 compliant, and accurately measures direct tension in the fastener within±5%. It provides absolute, realtime knowledge of fastener tension and performance — from installation through the full 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, says the company. — Valley Forge & Bolt Mfg. Co., Phoenix, Ariz.