S135 drill pipe is a low-alloy high-strength structural steel, belonging to the high-end drilling steel pipe category in the API (American Petroleum Institute) standard system. Its material properties include high strength, high toughness, and good fatigue resistance, making it particularly suitable for drilling operations in extreme environments such as deep sea and high-pressure oil and gas fields. Compared to ordinary carbon steel, S135 achieves a balance between tensile strength and ductility through precise alloy proportions and heat treatment processes, meeting the dual requirements of "high strength + high reliability" for oil drilling pipes.
S135 Drill Pipe chemical composition
| Composition | Content Range % |
|---|---|
| C | 0.90~1.10 |
| Si | 0.15~0.40 |
| Mn | 0.25~0.55 |
| Cr | 1.30~1.60 |
| P | ≤0.035 |
| S | ≤0.030 |
| Ni | ≤0.40 |
| Mo | ≤0.10 |
API 5DP S135 Drill Pipe Mechanical properties
| Performance Index | Standard Requirement |
|---|---|
| Yield Strength | ≥135ksi (931MPa) |
| Tensile Strength | 145~165ksi (1000~1138MPa) |
| Elongation | ≥10% |
| Impact Toughness | ≥27J (-20℃) |
Applications
The core applications of S135 drill pipe are concentrated in high-strength demand scenarios:
- Oil drilling: As the main body of drill pipes in deep-sea and high-pressure oil and gas fields, an offshore oilfield project used φ114mm S135 drill pipes, which successfully withstood drilling pressure of 90MPa in a water depth of 3000 meters. Its fatigue resistance extended the service life of the drill pipes to 1.5 times that of conventional steel grades.
- Nuclear power auxiliary systems: In the feedwater pipelines of the AP1000 unit, S135 steel pipes have passed NACE MR0175 acid environment certification, resisting long-term corrosion from high-temperature and high-pressure water media.
- High-pressure engineering machinery: Used for hydraulic support columns and high-pressure oil pipes, a coal mine project used a hydraulic system made of S135 steel pipes, achieving leak-free operation for over 8000 hours at a working pressure of 31.5MPa.
