API Spec 5DP S-135 drill pipe is a high-strength drill pipe (yield strength 135 ksi / 931 MPa) used in harsh conditions such as deep wells, ultra-deep wells, and directional wells. The complete specification system is as follows

Standard coverage: 2-3/8" ~ 6-5/8" (60.32 mm ~ 168.28 mm)

I. Upset Type

IU (Internal Upset): Internally thickened

EU (External Upset): Externally thickened (most common)

IEU (Internal-External Upset): Internally and externally thickened (high torque)

II. Connection Thread Type

NC Series (Digital Thread): NC26, NC31, NC38, NC40, NC46, NC50

IF ​​Series (Flat Thread): 2-3/8" IF, 2-7/8" IF, 3-1/2" IF, 4-1/2" IF

FH Series (Through-Hole Thread): 5-1/2" FH, 6-5/8" FH

III. Length Range

R1: 18–22 ft (5.49–6.71 m)

R2: 27–30 ft (8.23–9.14 m) (Standard common)

R3: 38–45 ft (11.58–13.72 m) (Deep Water / Deep Well)

IV. S-135 Steel Grade Properties

Yield Strength: ≥ 135 ksi (931 MPa)

Tensile Strength: ≥ 150 ksi (1034 MPa)

Hardness: HRC 28–36

Applications: Deep wells, ultra-deep wells, high torque, high fatigue conditions

V. Examples of Common Combination Models

3-1/2" EU NC38 S-135 R2

4-1/2" IEU NC46 S-135 R3

5" EU NC50 S-135 R2

5-1/2" EU 5-1/2" FH S-135 R2