1. Safe use of all wrenches requires that the user always be alert and prepared for the possibility that the wrench may slip, the fastener may suddenly turn free, or the wrench or fastener may break.
2. Where possible, use penetrating oil to loosen tight nuts.
3. The user must always inspect the wrench for flaws. Keep jaws sharp and clean. Gripping teeth or smooth jaws should not be worn or damaged.
4. Place the wrench so the pull on the handle tends to force the jaws further into the nut (lower jaw leads).
5. Pulling on a wrench is safer than pushing.
6. Open end wrenches have strong jaws and are satisfactory for medium-duty turning.
7. Replace an open end wrench if the jaws are no longer square.
8. Box and Socket Wrenches are necessary for a heavy pull. Never overload the capacity of a wrench by using a pipe extension on the handle or be striking the handle with a hammer.
9. Replace a box end wrench if the box edges aren’t sharp or true.
10. Socket and Adjustable Wrenches should be kept clean of dirt and grime inside the socket to ensure that the tool fits securely on the bolt or nut.
11. Replace an adjustable wrench if the jaws have noticeable play, the mechanism slips or binds, or the jaws are rounded.
12. Shift wrenches must work freely and adjust properly. Always use the proper size wrench for the job.
13. Replace a socket wrench if the wrench binds, if the locking mechanism no longer holds or the wrench won’t easily switch from forward to reverse.
14. Replace individual sockets if they are cracked, they don’t stay on the wrench or extension, or if the faces or corners are no longer true.