Direct Tension Indicator Washers
ANSI/ASME B 18.2.6M-2012
Metric fasteners for use in structural applications--Type Direct Tension Indicators
Tension holds a bolt in place. Having the right tension on the bolt is critical to correct installation. If the bolt tension is too tight it can cause the threads strip or the bolt to break – too weak can cause the bolt to loosen and become unstable. Many people try to ensure proper installation by measuring torque, yet the same torque, applied to the same bolts, out of the same box will result in varying tensions. In fact, a brand new bolt will require +/-40% torque to achieve the same tension as another new bolt out of the same box. To get the bolt properly secure, you must have the right tension – not torque!