Can torque to specification be reused?

Can torque to specification be reused?

The difference between a torque + angle specification and a torque + angle-to-yield specification is that the tightening results in permanent deformation of the externally threaded fastener. Externally threaded fasteners tightened to this specification method must not be reused and must ALWAYS be replaced if loosened.

Why do you have to replace torque to yield bolts?

If removed and reused, it is likely that either the head gasket will fail (due to low clamp load) or the bolts will break. 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.

What does it mean to torque to yield?

A torque to yield fastener (TTY) or stretch bolt is a fastener which is torqued beyond the state of elasticity and therefore undergoes plastic deformation, causing it to become permanently elongated.

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.

Is it safe to reuse torque to yield bolts?

Torque-to-yield (TTY) head bolts are designed to stretch when used. Once stretched, they are not as strong as before. Consequently, they cannot provide the same amount of clamping force and may break or shear off if reused.

Is it bad to reuse torque to yield bolts?

Can I reuse a torque to yield bolt?

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.

What is a torque to yield bolt?

How do you calculate the yield strength of a bolt?

Yield Strength Take the minimum yield in psi of the ASTM grade (see our Strength Requirements by Grade Chart for this value), multiplied by the stress area of the specific diameter (see our Thread Pitch Chart). This formula will give you the ultimate yield strength of that size and grade of bolt.

What is the point of torque to yield bolts?

Can you torque a bolt twice?

A bolt that has already been used in a given application may or may not be reused, depending on the grade, application, and recommendation of the “Engineer of Record”. Touching up or re-tightening bolts that may have been loosened by the installation of adjacent bolts shall not be considered to be a reuse.”