drill pipe

Don’t be Afraid to Ask Questions – Important Things to Know About Drill Pipe

In the past, we have written about tips for selecting proper drill pipe and drill pipe maintenance. What do you need to know when it comes to this important purchase?

Here are some insights to what you need to keep in mind.

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The most important thing I can advise about selecting drill pipe for your project is to ask questions. What kind of questions, you ask? Here are a few to keep in mind: Who is the manufacturer of the drill pipe and what is the origin of the tubes and tool Joints. If selecting new drill pipe, ask for the data packet or quality documentation package and go look at the pipe. Ask for a plant tour to see the pipe and the manufacturing process. If selecting or comparing used drill pipe, be sure to see the inspection reports and ask for clarification to make sure you understand the information. Study the O.D. of the pipe in comparison to the O.D. of new pipe and the minimum O.D. allowable for a connection to pass an inspection.

Today, we are going to discuss things you should know about your drill pipe.

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Don’t Overlook This

Pipe dope application procedures may be the most overlooked and most important thing to know. New threads on new pipe, or freshly recut connections, need special attention to “break-in” during their initial use. We often say, “Only put dope on the threads you want to keep.” But all jokes aside, the biggest problem we see when contractors have a problem with new threads is a lack of complete coverage of all threads and seal faces, deep down into the valley of the threads. All thread compounds (pipe dope) are not created equally. Pipe that has been stored for a long period of time should have “storage compound” such as ZN50. High quality pipe dope such as Kopr Kote can harden if left on threads for a long period of time as a storage compound and create a new set of problems. Avoid putting the pipe into service until storage compound has been removed and fresh new pipe dope has been applied.

Proper cleaning of threads before use is also a key step that is sometimes overlooked. After removing the thread protectors, threads need to be cleaned and checked before use. Mineral spirits are often used, or a high-pressure washer can be sufficient most of the time. The key is getting the threads clean so a visual inspection can verify their condition. Then pipe dope can adhere to the threads and protect them. Again, with complete coverage of all threads and seal faces.

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Drill pipe that is stored for a long period of time should be periodically rotated to prevent “rack rot.” We have seen pipe that is sitting on wood timbers develop rust where the steel contacts the wood and moisture. This can cause pitting that could lead to a failure.

Also Important

Make Up Torque and Initial Break-In of New Connections: The speed of rotation during break-in of new threads is critical and should be slow and steady. Most experts and manufacturers agree that it is best to make-up the connection to 100 percent of recommended make up torque. For example, manufacturers typically complete a three-cycle make and break at the factory when making maxi rig drill pipe. This is done at 100 percent of recommended make up torque on the tool joints before they are welded onto the tubes.

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Hard Banding: Hard banding can extend the life of drill pipe when used on rock crossings. Some manufacturers or suppliers install different types of hard banding. Hard banding can be most beneficial in rock formations to help reduce tool joint O.D. wear. Some hard band options are “casing friendly,” but they do not last as long in abrasive rock formation as other types of hard band. The placement of the hard band for HDD projects can be different than what is found on oil/gas (vertical) well projects. It is beneficial to place hard band on the tapers of the tool joints to prevent wear in a horizontal directional drilling.

Most HDD contractors prefer to use standard, field proven API style connections such as 4-1/2-in. IF, 5-1/2-in. Full Hole or 6-5/8-in. Full Hole. These connections are available in their standard form, or with a “double shoulder” feature. The double shoulder versions of these connections provide a secondary shoulder at the end of the pin. This adds approximately 30 percent more torsional strength to the connection and helps prevent over-torque to the connection if “slip torque” is experienced downhole.
Inspection and Stress Cracks: Stress is not measurable until a crack develops. Steel has a “memory” and is cumulative also referred to as fatigue. There is no way to quantify how much stress is put into a joint of pipe until a crack develops. Regular inspection is the best protection to look for cracks before they propagate all the way through the pipe which is seen as a joint with drilling fluid leaking through it, or a completely broken piece of pipe. Manufacturers have worked with heat treating methods as well as steel components to achieve “leak before break”. The goal is to have the pipe stay together even if a leak develops to avoid a downhole break. It is best to inspect drill pipe regularly, or after a particularly rough job and especially if the pipe has been used on a tight radius. The most common failures we find from HDD projects are noted as “rotational bending fatigue.” Meaning that the pipe has been through a tight radius while rotating and drilling.

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Again, I stress: Ask questions. Drill pipe suppliers and manufacturers see drill pipe on a regular basis and should be able to provide informative information through resources such as manufacturers, API and T.H. Hill.

Jay Miller is president of J.T. Miller LLC.

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