Structure of the Drill Pipes

Date:2024-07-30Tags:Drill Pipes, seamless steel pipes
Drill pipes are crucial components of drilling rigs, directly involved in the drilling process. In coal mining and other geological exploration projects, they play an irreplaceable role. Geological exploration drill pipes are used for water exploration, gas exploration, and drilling in coal mines. These include conventional drill pipes for coal mine tunnels, exploration drill pipes under 89mm for oil drilling, and down-the-hole drill pipes for rock drilling in mines. As the basic component of the drill string, usually connected to a drill collar,drill pipes are generally made of seamless steel pipes (with a wall thickness of 9 to 11mm). Their primary functions are to transmit torque and transport drilling fluid, and they lengthen progressively to deepen the borehole. Therefore, drill pipes hold a significant position in drilling operations.

Material of Drill Pipes

The material requirements for drill pipes vary depending on the type of drilling operation. For standard coal field drilling tasks, regular DZ40 or 45# steel is typically used. When using diamond bits to drill into rock formations, R780 or DZ50 material drill pipes are preferred. In the oil drilling sector, higher-grade alloy tubes are commonly used. Steel drill pipes are the most prevalent, with special steel alloys, usually high-strength, low-alloy steel (HSLA), being selected for their ability to withstand the harsh conditions of drilling, including high stress, corrosion, and wear.

Other Names for Drill Pipes

Drill pipes are also known as imitation English drill pipes, round drill pipes, outer flat drill pipes, geological alloy drill pipes, conventional coal mine tunnel drill pipes, exploration drill pipes, and down-the-hole drill pipes. These pipes are primarily used in coal mines for water exploration, gas exploration, and drilling construction. Our geological drill pipes include conventional drill pipes for coal mine tunnels, exploration drill pipes under 89mm for oil drilling, and down-the-hole drill pipes for rock drilling in mines.


Drill Pipes


Specifications of Drill Pipes

Diameter: Φ34.0mm, Φ42.0mm, Φ50.0mm, Φ63.5mm, Φ73.0mm, Φ89.0mm
Length: 0.5m, 0.8m, 1.0m, 1.5m
Drill pipes consist of seamless steel pipes with a wall thickness of 9 to 11mm and comprise two parts: the drill pipe body and the drill pipe joint. Common drill pipe diameters include Φ34mm, Φ42mm, Φ50mm, Φ60mm, Φ63.5mm, Φ73mm, and Φ89mm. Geological exploration commonly uses 42mm and 50mm pipes, while larger diameter geological drill pipes are used for drilling large diameter water wells or oil wells.
Length of Drill Pipes
Regarding length, drill pipes can be customized according to customer requirements without compromising the manufacturing process. Common lengths include 0.5m, 1m, 1.5m, 2m, 2.5m, 3m, and 4m, with 1m and 1.5m lengths being the most common. For deeper drilling, it is generally advisable to use drill pipes longer than 3 meters, but shorter drill pipes can be used with rope-type drilling tools for easier installation and disassembly.

Connection Types of Drill Pipes

Connection Types: Flat Thread, Tapered Thread
Flat Thread: Φ34.0mm, Φ42.0mm, Φ50.0mm
Tapered Thread: Φ63.5mm, Φ73.0mm, Φ89.0mm
Smaller diameter geological drill pipes generally use flat thread connections. As the diameter increases, the depth and torque of the borehole also increase, necessitating the use of tapered thread connections to ensure torque transmission and facilitate disassembly. Customization is available to meet special customer requirements.

Structure of Drill Pipes

Drill pipes are primarily composed of seamless steel pipes, consisting of the drill pipe body and the drill pipe joint. Detailed as follows:
Drill Pipe Body: Typically made from seamless steel pipes with a wall thickness of 9 to 11mm. The ends of the pipe body can be connected to joints through fine thread connections or friction welding. Friction welded drill pipes (without fine threads) have largely been phased out, and now, all domestically produced or imported drill pipes are friction welded.
Drill Pipe Joint: The joints are divided into male and female joints, connected at both ends of the pipe body. The joint diameter is larger than the pipe body diameter, continually contacting and wearing against the wellbore or casing during drilling. To prevent joint wear, which could lead to broken pipes or disconnection, a wear-resistant band must be placed on the female joint.
Material and Steel Grade: Drill pipe materials can include steel, aluminum alloy, titanium alloy, and composites. Steel pipes are widely used due to their mature manufacturing process and low cost. The steel grade of a drill pipe is determined by its minimum yield strength, with API standards specifying grades D, E, 95(X), 105(G), and 135(S).
Special Types: For example, double-wall drill pipes, composed of inner and outer pipes with an annulus between them, are used in hydraulic rock drilling and core sampling to pump flushing medium to the bottom of the hole.
These structural features allow drill pipes to withstand significant internal and external pressures, torsion, bending, and vibration in applications like oil drilling.

Applications of Drill Pipes

Fields of Application: Drill pipes are widely used in coal mining, mining, construction, water conservancy projects, railways, highways, and bridge tunnels for drilling, excavation, and anchoring. In coal mines, they are primarily used for water exploration, gas exploration, and tunnel exploration.


Advantages of Drill Pipes

The main body of the drill pipe uses special geological alloy steel, and the joints use alloy structural steel, manufactured through high-pressure forming, vacuum tempering, friction welding, and overall surface hardening. Threads are machined using automated equipment to ensure precision. The process of welding before threading ensures that multiple connected drill pipes maintain coaxial alignment during deep hole drilling. Compared to similar products, these drill pipes offer high bending strength, large torque transmission, and smooth operation.

In summary, the structure and common specifications of geological drill pipes are continually evolving. The growing market for drill pipes, both domestically and internationally, drives increasing user demand. Drill pipes have become integral to the modern coal mining industry, and enhancing their performance and market presence can bring significant benefits to the coal mining sector.

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