Heavy weight drill pipe is a medium-weight drill tool similar to drill pipe, whose wall is thicker than that of drill pipe and thinner than that of drill collar. Its tube is connected with special length-added drill pipe joint (integral heavy weight drill pipe is made up of tube and tool joint). Among assemblies, it is generally added between drill pipe and drill collar to prevent sudden changes in cross-section of drill string, and reduce its fatigue. Using it to replace part of the drill collar can reduce torque, improve load, and increase drilling ability during deep well drilling; meanwhile pick-up sub and safety clamp will not be used drilling operation ,which is easy to operate and can save tripping time. It can drill in in high speed under low torque in directional wells and reduces the abrasion and fracture of string without differential pressure and sticking because of the lower steel grade than drill collar, small touching area with the well wall.

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CHEMICAL COMPOSITION

Integral heavy weight drill pipe

Size Outer diameter Inside diameter Joint outer diameter Joint inside diameter Connecting thread Slip max. diameter Upset middle diameter Min. drift diameter

3 1/2 3 1/2 2 1/4 4 3/4 2 1/4 NC38 3 7/8 4 2

2  1/16 (4 7/8, 5) 2  1/16 1 13/16

4 4 2 1/2 5 1/4 2 1/2 NC40 4  3/16 4 1/2 2 1/4

2  9/16 2  9/16 2  5/16

4 1/2 4 1/2 2 11/16 6 1/4 2 11/16 NC46 4 11/16 5 2  7/16

2 3/4 2 3/4 2 1/2

2 13/16 2 13/16 2  9/16

5 5 3 6 5/8 3 NC50 5 1/8 5 1/2 2 3/4

5 1/2 5 1/2 3 1/4 7 3 1/4 5 1/2 FH 5 11/16 6 3

3 3/8 (7 1/4, 7 1/2) 3 3/8 3 1/8

3 7/8 3 7/8 3 5/8

4 4 3 3/4

6 5/8 6 5/8 4 8 4 6 5/8 FH 6 15/16 7 1/8 3 3/4

4 1/2 (8 1/4, 8 1/2) 4 1/2 4 1/4

5 5 4 3/4

Spiral heavy weight drill pipe

Specification  mm Tube Joint

ID mm Elevator upset

mm elevator groove

/Slip outside diameter

  mm Screw in diameter

mm Spiral groove depth

mm Thread Type OD mm ID mm

88.9(3 1/2) 54 92.1 88.9 101.6 9.5 NC38 120.6 54

114.3(4 1/2) 69.8 117.5 114.3 127 12.7 NC46 158.8 69.8

127.0(5) 76.2 130.2 127 139.7 12.7 NC50 165.1 76.2

Steel Mark Chemical Composition%

C Si Mn P S Cr Mo Cu Al

4145H 0.42～0.48 0.15～0.35 0.90～1.20 ≤0.03 ≤0.03 0.90～1.20 0.15～0.25 ≤0.2 0.025～0.045

Other Elements：N≤0.015，Ni≤0.5

Yield strength Tensile Strength Elongation

A%

HB Charpy impact

Akv  J

MPa Psi MPa Psi

≥758 ≥110000 ≥965 ≥140000 ≥13 285～341 ≥54

Product superiority:

In the process of heat treatment, a normalizing process is added, which makes the threads more granular, increases the thread strength, and effectively improves the service life of the product.

Weld heavy weight drill pipe:

Using the current domestic and foreign advanced heat treatment technology of friction welding deformation ,and heat affected zone smaller， welding process more simple and strict welding deformation and heat treatment standard procedure qualification, tuning parameters to ensure better welding quality more stable and reliable.

Welded heavy weight drill pipe

Type Outer diameter Inside diamter 

   mm Joint type

mm in

MJZ29-NC31-I/II 73.03 2 7/8 50.8 NC31

MJZ35-NC38-I/II 88.9 3½ 57.15 NC38(3½ IF)

52.39

MJZ40-NC40-I/II 101.6 4 63.5 NC40(4FH)

65.09

MJZ45-NC46-I/II 114.3 4½ 68.26 NC46(4IF)

69.85

71.44

MJZ50-NC50-I/II 127 5 76.2 NC50(4½ IF)

MJZ55-5½ FH-I/II 139.7 5½ 82.55 5½ FH

85.72

98.42

101.6

MJZ66-65/8FH-I/II 168.3 Aug-65 101.6 65/8FH