Drill pipe is a fundamental component of the drill string. It is made of seamless steel pipe (with a wall thickness typically between 9 and 11 mm). Its main functions are to transmit torque and deliver drilling fluid, and to deepen the wellbore by gradually lengthening the drill pipe. Choosing the correct drill pipe size is crucial for maintaining drilling efficiency, safety, and structural integrity. Today, we'll discuss drill pipe dimensions.
A typical drill pipe consists of three main parts:
Tube (body) – the long hollow section of the pipe
Tool joints – threaded connections welded to both ends
Upset sections – thickened pipe ends to strengthen connections
For this reason, drill pipes are manufactured according to strict API standards and metallurgical requirements.
The outside diameter (OD) of a drill pipe affects its strength and ability to transmit torque during drilling operations. It also determines compatibility with other drill string components such as drill collars and downhole tools. In most drilling projects, common OD sizes range from 2 3/8 inches to 6 5/8 inches.
2.Inside Diameter (ID)
The inside diameter (ID) controls the circulation capacity of drilling fluid inside the pipe. A larger ID allows higher flow rates, helping remove cuttings, cool the drill bit, and maintain stable well pressure during drilling.
Grade Selection Guidelines
E75 – shallow wells and light drilling
X95 – moderate depth wells
G105 – high stress environments
S135 – deep wells and high torque drilling
Higher grade pipes provide better fatigue resistance and tensile strength.
What Is Drill Pipe?
Drill pipe is a heavy-duty seamless steel pipe used in drilling rigs to form the drill string. It transfers rotational power from the rig to the drill bit and circulates drilling fluid downhole.A typical drill pipe consists of three main parts:
Tube (body) – the long hollow section of the pipe
Tool joints – threaded connections welded to both ends
Upset sections – thickened pipe ends to strengthen connections
For this reason, drill pipes are manufactured according to strict API standards and metallurgical requirements.
Standard Drill Pipe Size Chart
Below is a commonly used API drill pipe size chart, including outside diameter, nominal weight, and typical tool joint sizes used in oilfield operations.| Drill Pipe Size | |||||
| Size | Nominal Weight | Calculated Weight Wpe (Lb/ft) | Grade | Wall Thickness | Upset Ends. For Weld-on Tools Joint |
| 2 3/8" | 6.65 | 6.26 | E、X、G、S | 0.280" | EU |
| 2 7/8" | 10.4 | 9.72 | E、X、G、S | 0.362" | IU or EU |
| 3 1/2" | 9.5 | 8.81 | E | 0.254" | IU or EU |
| 3 1/2" | 13.3 | 12.31 | E、X、G、S | 0.368" | IU or EU |
| 3 1/2" | 15.5 | 14.63 | E | 0.449" | IU or EU |
| 3 1/2" | 15.5 | 14.63 | E、X、G、S | 0.449" | EU or IEU |
| 4" | 14 | 12.93 | E、X、G、S | 0.330" | IU or EU |
| 4 1/2" | 13.75 | 12.24 | E | 0.271" | IU or EU |
| 4 1/2" | 16.6 | 14.98 | E、X、G、S | 0.337" | EU or IEU |
| 4 1/2" | 20 | 18.69 | E、X、G、S | 0.430" | EU or IEU |
| 5" | 16.25 | 14.87 | E、X、G、S | 0.296" | IU |
| 5" | 19.5 | 17.93 | E | 0.362" | IEU |
| 5" | 19.5 | 17.93 | E、X、G、S | 0.362" | EU or IEU |
| 5" | 25.6 | 24.03 | E | 0.500" | IEU |
| 5" | 25.6 | 24.03 | E、X、G、S | 0.500" | EU or IEU |
| 5 1/2" | 21.9 | 19.81 | E、X、G、S | 0.361" | IEU |
| 5 1/2" | 24.7 | 22.54 | E、X、G、S | 0.415" | IEU |
| 6 5/8" | 25.2 | 22.19 | E、X、G、S | 0.330" | IEU |
| 6 5/8" | 27.7 | 24.21 | E、X、G、S | 0.362" | IEU |
| Mechanical Properties | ||||||
| Steel Grade | Yield Strength | Tensile Strength > | ||||
| >Min. | Max | Min. | ||||
| Psi | Mpa | Psi | Mpa | Psi | Mpa | |
| E-75 | 75,000 | 517 | 105,000 | 724 | 100,000 | 689 |
| X-95 | 95,000 | 655 | 125,000 | 862 | 105,000 | 724 |
| G-105 | 105,000 | 724 | 135,000 | 931 | 115,000 | 793 |
| S-135 | 135,000 | 931 | 165,000 | 1138 | 145,000 | 1000 |
Drill Pipe Dimensions Explained
1.Outside Diameter (OD)The outside diameter (OD) of a drill pipe affects its strength and ability to transmit torque during drilling operations. It also determines compatibility with other drill string components such as drill collars and downhole tools. In most drilling projects, common OD sizes range from 2 3/8 inches to 6 5/8 inches.
2.Inside Diameter (ID)
The inside diameter (ID) controls the circulation capacity of drilling fluid inside the pipe. A larger ID allows higher flow rates, helping remove cuttings, cool the drill bit, and maintain stable well pressure during drilling.
Drill Pipe Steel Grades
Drill pipes are manufactured in different strength grades according to drilling depth and load requirements.| Grade | Minimum Yield Strength |
| E75 | 75,000 psi |
| X95 | 95,000 psi |
| G105 | 105,000 psi |
| S135 | 135,000 psi |
E75 – shallow wells and light drilling
X95 – moderate depth wells
G105 – high stress environments
S135 – deep wells and high torque drilling
Higher grade pipes provide better fatigue resistance and tensile strength.
