How many times can you use torque to yield bolts?
What is a torque-to-yield bolt? It is a one-time-use fastener that is designed to stretch during the torquing process (installation). Because of this stretching, the integrity of the bolt is compromised. These bolts cannot and should not be reused due to the stress caused to the bolt during its first installation.
Can you reuse bolts that have been torqued?
Mechanically, bolts may be reused provided the bolt never exceeded its yield point: a simple enough definition, but one that is more complicated than it may appear. This is because it is nearly impossible to verify if a bolt has ever been tensioned past the yield point.
Why do you have to replace torque to yield bolts?
You should always replace the T-T-Y bolts; these bolts are designed to stretch, and reusing them will cause improper, uneven torque and clamping force. Yielded bolt threads can damage threads in the engine, especially on aluminum blocks, and since the bolts are weakened, they may break if retorqued.
Should I’re torque head bolts?
In most cases you don’t need to retorque head bolts or studs. If the bolts or studs aren’t tight you will lose compression or get coolant in your cylinders. You can use bolts or studs based on application, but studs tend to give more consistent torque values. Never reuse Torque-To-Yield (TTY) bolts.
What happens if you reuse head bolts?
Can I reuse head bolts? A head bolt should not be reused if the threads are galled or badly damaged. Chasing damaged head bolt threads with a die will clean up the threads but also remove material (metal) and undermine the head bolt’s ability to torque down and hold to specs.
What happens if you over torque a torque to yield bolt?
If the bolt is over-torqued and stretched beyond its limit, this exceeds its yield strength which means it can no longer maintain the needed clamp load and must be replaced. Finally, using a breaker bar, the bolt is tightened, which moves the dial to the specified angle – hence the term torque-angle.
Can flange nuts be reused?
Flange lock nuts are reusable but only for a limited number of times because the prevailing torque declines each time the nut is used. Always follow the manufacturer’s recommendations regarding nut reuse, thread lubricants and torque values.
Do torque to yield bolts have to be replaced?
Torque to yield bolts must be replaced to get proper torque retention. Due to the design they stretch during torque process. See a TTY bolt is generally torqued in stages Then turned a set number of degrees to force bolt to yield/stretch to maintain static tension.