Drill Master: Making the “Exit Side” a Safer Place to Work
Either you have had the unfortunate personal experience of, or could imagine the dangers of, the common practice of using a pipe wrench and backhoe to unscrew a threaded tool or pipe connection on the exit side of an HDD bore. This is by far the most dangerous operation relating to injury and fatalities of the entire HDD process. Equipment manufacturers have offered multiple fixes for this hazard with varying degrees of success.
The threaded connection is the undisputed best method to secure tooling to the drill string considering cost, reliability and long-term wear of the connection. The question is how can this threaded connection be broken-out (unscrewed) or made-up (tightened) safely and under total control. The answer is the new generation of hydraulic operated tongs, often called Safety Tongs. Because they are hydraulically operated, the operator can be 15 to 20 ft (4.5 to 6 m) away from the connection as it is being torqued. A pressure gauge will tell the operator the torque that is being applied. In fact, the operator does not have to see the tongs being operated, making for a very safe and controlled operation.
During make-up of a connection, the operator can observe the pressure gauge that relates the torque being applied to the joint. Proper make-up torque can be achieved. Under torqueing of a connection is one of the primary causes of joint failure. Thus, proper joint make-up can help avoid in hole joint failures. Avoiding one failure can easily pay for a set of safety tongs.
A pipe or similar wrench will actually squeeze the outside diameter of a connection. If the wrench grips too hard, it squeezes the would-be-round connection into an oval, actually making the connection harder to unscrew, as well as damaging the integrity of the tool joint. It is not recommended to use any type of device that contacts the tool joint at concentrated points.
There are things to watch for when shopping for make-up/break-out devices. A device that provides for a wide contacted area with the pipe is preferred. Most commonly, a chain tong is best suited to meet this requirement. The chain tong will give adjustability to easily fit different diameter connections making it very versatile and useable for multiple connection sizes. The chain tong grips around most of the circumference of the connection, applying a relatively equal radial loading and not causing distortion or damage to the connection. The greater the applied torque to the connection, the tighter the tong grips the pipe.
A good make-up/break-out device will most likely be hydraulically operated to allow the operator to control and operate the device from a safe distance. Some devices are operated by a screw mechanism, requiring the operator to be right next to the tool during operation. While being lower in cost and for the most part effective, they allow little margin of safety for the operator if a failure should occur. The operator is right next to the action.
The solution for making the make-up/break-out tasks of your operation safe and controlled is now readily available. The cost of a good device for make-up/break-out is reasonable; a human life is priceless.
