30 MAY 2025 WorldWide Drilling Resource® Selecting the Right Size Casing Hammer Adapted from Information by Atlas Manufacturing, Ltd. When adding a casing hammer to a drill rig, it’s important to select the correct size. To determine what size hammer will fit in your mast, begin with the rig’s tophead travel measurement. This will tell you how long your hammer can be; the inside width of the mast will tell you how wide your hammer can be. The right amount of tophead travel will provide the room necessary to fit the hammer and give the amount of drill out you require. When you decide on the model of hammer required, you will have to verify whether or not it will work on the rig you are planning on using and whether it will give the amount of drill out you need. An easy way to figure this out is to add the length of the hammer to a length of drill rod. You will need this length just to fit the hammer into the drill string. Any extra is your drill out. For example, 20 feet for the drill rod and five feet for the hammer would be 25 feet. If you have 26 feet of tophead travel, you will have one foot of drill out; if you have 29 feet of tophead travel, you will have four feet of drill out. The inside width of the mast should be wide enough to accommodate mast guides; adding the hammer width and guide width will equal the minimum inside mast width. The minimum amount of room necessary to fit the hammer into the mast with guides would be the hammer width plus one inch on each side of the hammer. Guides are always made to fit the mast. So when the hammer and the rig are known, the appropriate guides can be supplied with the hammer. Rigs come in many shapes and sizes, so there are many options for guides available. Truss style masts can use simple bolt on mast guides or extra rails can be added that will allow the hammer to be hydraulically swung out of the mast so other types of work can be done that doesn’t require the hammer. A single pole mast can be used with simple bolt on mast guides or a swing out hammer sled can be added to allow the hammer to be hydraulically swung out to the side for work not requiring the hammer. Different drilling conditions require different amounts of force to hammer pipe into the ground. It can require as much force to drive a small pipe into hard ground as a large pipe into soft ground, so ground conditions alone or pipe size alone are not a good method. If you are driving pipe ahead instead of drilling a hole first to drive into, it will require a larger hammer. A good way to narrow down your choices is to look at what other drill operators are using in similar conditions and how successful they are. If you’re not sure if a particular size hammer is big enough or is too big, some hydraulic hammers can have their stroke adjusted to lessen the force. With 12 models available, the Atlas Manufacturing line of casing hammers are adaptable to almost any rotary or cable tool rig. WTR Tophead Photo courtesy of Geoprobe®. j Sand j Manholes j Bentonite j Filter Sock j Sampling Bailers j Clear PVC Pipe j Locking Caps Atlantic Screen & Mfg., Inc. Manufacturers of Slotted & Perforated Pipe Ranging from 1/2” to 24” in Diameter 302-684-3197 FAX 302-684-0643 142 Broadkill Rd j Milton, DE 19968 www.atlantic-screen.com e-mail:atlantic@ce.net
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