1. The document discusses how to properly torque fasteners using a torque wrench. It notes that over-torquing or under-torquing fasteners can cause failures through mechanisms like loosening, shearing, or fatigue. 2. Key steps for torquing a fastener include preseting the torque wrench to the specification, typically provided by the manufacturer, then tightening the fastener until the wrench clicks to indicate the set torque has been reached. 3. Factors like lubrication, impact wrench use, or potential safety risks can require adjusting torque or replacing fasteners. Proper torque is crucial for maintaining tension and loading of parts.

1. How to Torque Fasteners?
“GANG BOX TRAINING”
General Rules which must be followed: • A torque wrench is used where the tightness of
screws and Fasteners is crucial.
1. Never over torque a Fastener. To over-torque a • It allows the operator to measure the torque
Fastener can cause it to stretch beyond normal
limits causing Fastener breakage, or loosening applied to the fastener so it can be matched to
of Fastener the specifications for a particular application.
2. Never under torque Fasteners because it can This permits proper tension and loading of all
cause the Fastener to loosen to break parts.
3. Ensure you know the torque specification
4. Ensure you know the torque specification if you How to Torque a Fastener?
are using a Fastener with lubricant on it or dry
5. As a general rule Fasteners should be lubricated
unless manufacturer states otherwise Using the most common torque wrench which is a
6. Know how to use a torque wrench. When all else “click type” follow these steps;
fails read the instructions. Step 1: Preset torque value on torque wrench as
7. When unsure whether a Fastener should be determined by the equipment manufacturer; or if not
torque to a specification, torque it available a common torque specification chart. (see
8. Do not re-use a Fastener if: below)
- If it was installed with an impact wrench
- If it could result in a safety risk
Fastener Failure Modes:
• Overloading – Force exceeds Fastener
strength, Fastener loosens or shears
• Over-Torque - damaging the threads and
deforming the hardware
• Under-Torque - allowing a joint to come loose. It
may also allow the joint to flex and thus fail
under fatigue.
• Brinelling – caused by poor quality washers,
leading to a loss of clamp load and failure of the Note: When using anti-seize reduce lube torque
joint value by 20%
• Corrosion – caused by the disintegration of an
engineered material due to electrochemical Step 2: Torque the Fastener to the point where the
oxidation of metals in reaction with an oxidant desired torque is reached, signaling the desired
such as oxygen, this is why Fasteners must be torque by causing a click sound (some torque
lubricated unless stated by the equipment
wrenches will not allow a Fastener to be torque
manufacturer.
above the setting however some will, be sure and
Definitions: purchase the best torque wrench possible)
Torque Wrench: If you have questions send me an email at
• A torque wrench is a tool used to precisely apply rsmith@gpallied.com
a specific torque to a fastener such as a nut or
Fastener.
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