Sailors are often told, “One hand for the ship, one hand for yourself.” When sailors climb onto the rigging to change the sails, they are tempted to use both hands rather than keeping one hand on the rig to keep from falling overboard. The same advice applies to hand tool safety—when maintenance workers and contractors don't pay attention to how they use their tools, unfortunate situations can arise.

Too often, accidents occur because of carelessness or lack of training when using hand tools. Below are tips on general hand tool safety, with more specific direction on effectively and safely using wrenches:

There are basic hand tool safety guidelines that should always be followed, regardless of the industry or the user's experience. Remember the following when using a wrench and socket:

1. Always wear safety goggles to protect your eyes.
2. Never use “cheater bars” or hammers.
3. Inspect and discard bent, worn or cracked tools.
4. Use the correct drive size. Always choose the largest possible drive size—it is stronger and safer.
5. Use the correct size socket. Do not use metric sockets on English-size fasteners or vice versa, because the fit is not snug.
6. Place the socket all the way on the fastener.
7. The safest wrench is a box or socket type because it is stronger and less likely to slip off the fastener. Open end, flare nuts and adjustable wrenches are not as strong as box or socket wrenches. The former are not intended for heavy loads, such as breaking frozen fasteners loose or final tightening.
8. Avoid over-torquing. A torque wrench will permit tightening to the exact torque required for best performance and safety. A fastener that is over-tightened can be difficult to remove and may break during service from overloading.

To ensure proper hand tool safety, consider the wrench's drive size. Most sockets are available in at least three drive sizes. For example, a 9/16-in. socket is offered in ¼-, 3/8- and ½-in. drives. A ¼-in. drive socket is the least expensive and will work in the tightest space, but the handles are too short for heavy loads. If the handles were longer, the drive square would twist off before the fastener was fully tight or a tight fastener was removed. The ¼-in. drive socket is ideal for low-torque applications, such as electrical work, or in close quarters.

A 3/8-in. drive socket is 25 percent stronger, but also 0.022 in. larger in diameter than the ¼-in. drive socket. A ½-in. drive socket is an additional 21 percent stronger and 0.027 in. larger in diameter.

In general, it is safest to use the largest drive size possible unless the torque will be very low. The largest sockets in a particular drive are for light duty only. For example, it is preferable not to use ¼-in. drive sockets larger than 3/8-in., ½-in. drive sockets larger than 1-in., ¾-in. drive sockets larger than 1 3/8-in., 1-in. drive sockets larger than 2-in. and 1½-in. drive sockets larger than 3½-in. These limits are particularly important for Grade 8 fasteners, which are marked by three lines on the head. Larger drive sockets may be used for lower-grade sockets. Most sets of tools include larger size sockets.

Special care should be taken when using smaller sockets. A hard pull on the handle may overload the socket and/or the fastener. Remember, too, that the strength of larger sockets is limited by the drive square, meaning they are not appropriate for high-strength fasteners such as Grade 8 bolts or 12-point fasteners.

Industry standards dictate the appropriate handle length for each drive. If a tight fastener can't be turned with a smaller handle, the safe procedure is to use a socket of a larger drive and the corresponding longer handle. Hitting the handle with a hammer or lengthening it with a cheater bar may overload the fasteners, the socket or the handle and is never recommended.

It is very important that wrenches provide a close fit. The closer a wrench fits a fastener, the less chance there is of damaging the fastener. Newer wrench opening designs are much better at spreading the load over a large area and avoiding rounding off the corners of fasteners. In addition, quality manufacturers make sockets as close to the fastener sizes as possible.

All sockets wear out over time and will not fit the fastener as tightly as they did when they were new. Worn sockets should be replaced, especially when used on high-strength or 12-point fasteners.

That's because worn sockets are weaker and more likely to round the corners of fasteners. The socket should be discarded when the nut end is worn, if it feels sloppy on a fastener or if the socket's drive square is sloppy and mushrooming around the square drive.

If the user must loosen a worn fastener, a 6-point socket, in good condition, works better than a 12-point socket. Worn fasteners should not be reinstalled because they will be harder to remove the next time. For safety reasons, it is good practice to replace all used fasteners with new fasteners. If the square is worn on an impact socket, the user should inspect the drive square on the impact gun and replace it if it is worn.

Since the fit on a fastener becomes worse as a socket wears, look for wear in the nut end—if the difference is apparent, it should be replaced.

Another clue that a wrench is worn is if it feels sloppy on a fastener. Likewise, if the drive square is sloppy or shows signs of mushrooming around the square, the socket should be replaced. Worn sockets are not only weaker and less likely to do the required job, they are also more likely to round the corners of fasteners. Do not reuse fasteners with damaged heads as they will not allow good engagement.

The first step in freeing a fastener that can't be turned is to apply penetrating oil and let it soak in. If a fastener is rusted, tap it with a hammer to try to break it loose. If there is room, a larger drive with a longer handle may work. Using an adapter with a larger drive handle is not recommended, as something will most likely break, possibly even the user. Again, never use a cheater bar.

Next, try an impact gun and impact socket. This combination can deliver higher torque and won't send the user sprawling if the fastener suddenly turns or breaks. A slugging wrench, which is designed to be hit with a hammer, is another possibility with larger sizes.

Always remember, “One hand for the ship (or job) and one hand for yourself.”